WP 2 Report on Design Guidelines for New Concepts of ELTVs

Project nº 266222 Co-financed by European Commission

D2.4 – REPORT ON DESIGN GUIDELINES FOR NEW CONCEPTS OF ELTVs

Project Acronym: OPTIBODY

Project Full Title: “Optimized Structural Components and Add-ons to Improve Passive Safety in New Electric Light Trucks and Vans (ELTVs) "

Grant Agreement No.: 266222

Responsible: UNIZAR

Internal Quality Reviewer: POLITO

Version: 3 (2012-11-30)

Dissemination level: Public

EXECUTIVE SUMMARY:

This document is divided into 9 chapters.

Chapter 1 is completely introductory. It explains the objectives and scope of the document. It is explained that at the end of the project, a book titled “Recommended Practices in the Design and Manufacture of Electric Light Trucks and Vans (ELTV)” will be generated. This book will collect the most relevant project technical results.

Chapter 2 takes into consideration what the standards specify for the different vehicle categories in terms of total weight, nominal power, etc. OPTIBODY focuses on L7e vehicle category (unladen mass not more than 400 kg or 550 kg for vehicles intended for carrying goods, not including the mass of batteries in the case of electric

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vehicles, and whose maximum net engine power does not exceed 15 kW).

Chapter 3 expresses, derived from a benchmarking analysis of ELTVs in the market, the global expected specifications for a new electric light truck: NOMINAL POWER: up to 4 kW for L6e category; up to 15 kW for L7e; no limitation for N1 category. ENERGY CONSUMPTION: the average value for all vehicles included in the database (used for the benchmarking analysis) is around 140 kWh/km. RANGE: the average value for all vehicles included in the database is around 82 km. Some vehicles “declare” 100 km and just a few of the given greater range values. MAXIMUM VELOCITY: standards fix the maximum speed only for L6e category. For them, the maximum velocity is limited to 45 km/h. The average value for all vehicles in the database is around 50 km/h. Some L7e vehicles “declare” 60 km/h, some declare 80 km/h. TOTAL WEIGHT: standards regulate the weight of vehicles in the following way: L6e: unladen mass not more than 350 kg, not including the mass of the batteries in case of electric vehicles. L7e: unladen mass not more than 400 kg or 550 kg for vehicles intended for carrying goods, not including the mass of batteries in the case of electric vehicles. N1: The total vehicle weight must be less than 3.5 tons (including the payload). The average value for all vehicles in the database is around 725 kg. BATTERY CAPACITY: the average value for all vehicles in the database is around 11 kWh. Values go from 9 to 15 kWh. BATTERY WEIGHT: the average value for all vehicles in the database is around 230 kg. Values go from 160 to 380kg.

Chapter 4 covers the main issues related to the vehicle battery pack. The design guidelines related to energy storage devices are: SPECIFICATIONS ACCORDING TO STANDARDS: quadricycles (L7e), also referred to as Heavy Quadricycles, are defined by Framework Directive 2002/24/EC as motor vehicles with four wheels "other than those referred to (as light quadricycles), whose unladen mass is not more than 400 kg (category L7e) (550 kg for vehicles intended for carrying goods), not including the mass of batteries in the case of electric vehicles, and whose maximum net engine power does not exceed 15 kW. These vehicles shall be considered to be motor tricycles and shall fulfil the technical requirements applicable to motor tricycles of category L5e unless specified differently in any of the separate Directives". WEIGHT OF THE BATTERY PACK ACCORDING TO VEHICLE CATEGORY: as the

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WP 2 Report on Design Guidelines for New Concepts of ELTVs

Project nº 266222 Co-financed by European Commission

total allowed power is only 15 kW, the total vehicle weight (400 Kg or 550 without batteries) should be kept as small as possible to increase vehicle performance, and in consequence, the weight of the battery pack must be optimized. GENERAL REQUIREMENTS FOR TRACTION BATTERIES: the general requirements are, as for all battery applications: low cost, long life (more than 1000 cycles), low self-discharge rates (less than 5% per month) and low maintenance are basic requirements for all applications. But traction batteries have added requirements: generally operate in very harsh operating environments and must withstand wide temperature ranges (-30°C to +65°C) as well as shock, vibration and abuse. Also, low weight is however essential for high capacity automotive EV and HEV batteries used in passenger vehicles. Protection circuits are also essential for batteries using non-lead acid chemistries. BATTERY CHARGING: use of the recently approved European Charging connector. BATTERY PLACEMENT: battery placement is therefore critical. The battery pack is heavy and voluminous. In passenger cars typical, if only possible, solutions are: 1. Under the bonnet/hood. 2. In the tunnel. 3. In the trunk/luggage compartment. (The assumption is made that all the battery assembly is kept in a single pack). POSITIONING IN THE VEHICLE: Batteries in the tunnel: the battery pack is set in the tunnel, where usually is place for the transmission shaft to the rear differential in a rear-wheel traction or 4WD system. Placing the battery in the tunnel offers the following advantages: Dynamics: masses are distributed along the centre axis of the vehicle and in the lowest position; Crash: batteries are in a “safe” place with respect to side crash; Production: batteries are assembled with the drivetrain, no need to package batteries at the end of the assembly process; Economics: there are just a few changes on the chassis. Batteries in the trunk: above the rear axle. The battery pack is set above the rear axle, behind the second row of seats. In the case of a freight transport vehicle it would be behind the cabin. Placing the battery in the trunk offers the following advantages: Dimensions: there are few limitations on the size of the battery pack and its shape; several configurations of the battery pack can be adopted; Crash: batteries are placed in a secure place with respect to side crash; Economics: limited changes in the chassis; the pack is installed at the end of the assembly line in the trunk; drawbacks are the following: Dynamics: suspensions must be reinforced since a higher mass is standing on the rear axle; moreover, the dynamic behaviour of the

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vehicle will be affected by a different disposition of the masses; Production: batteries are separated from the drivetrain; therefore, they are installed at the end of the assembly line in the trunk, requiring special areas in the plant for such installation and dedicated work-force; STANDARDS AND REGULATIONS REGARDING SAFETY: safety issues of battery electric vehicles are largely dealt with by the international standard ISO 6469. This document is divided in three parts dealing with specific issues: On-board electrical energy storage, i.e. the battery; Functional safety means and protection against failures; Protection of persons against electrical hazards.

Chapter 5 focuses on the powertrain, in particular in the traction motors. OPTIBODY contemplates the use of in-wheel motors. This chapter performs a detailed study of the specific performance of electric vehicles (EV) with in-wheel motors, compared to traditional architectures with internal combustion engines (ICE). The chapter concludes that the acceleration capacity is rather different. The impact of the motors mass on the tire vertical dynamics is also analysed. Corrective measures are proposed, based on the damper modification: an increment of about 70 – 80 % of the damping ratio corrects the vertical dynamic behaviour of the wheel.

Chapter 6 indicates the vehicle weight reduction as a key design objective. Vehicle weight influence in fuel consumption is studied: not depending on the driving cycle used to calculate fuel consumption, there is a quasi-linear relationship between vehicle weight and fuel consumption. Vehicle weight evolution along the time is presented and the possible means to achieve substantial weight reductions are also described: optimised design and light materials.

Chapter 7 deals with ELTVs crashworthiness. Basic technical issues are described. Crash compatibility for ELTVs is analysed in detail. Design guidelines derived from the contents of this chapter are: INTERIOR GEOMETRY: Seating position must offer a good overview of the traffic situation for the driver to enhance active safety. It is got with a rather upright seating position. Also seating position results a little shorter ride- down distances for upper body parts. Given an adequate restraint system, an upright position will reduce forward rotation of upper body parts and then decelerations will be lower, especially on the head. RESTRAINT SYSTEM: It is necessary to provide

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an additional ride-down space in the vehicle interior. The components ought to deform ideally at a constant load level and the restraint systems must become active as soon as possible. ABSORPTION OF COLLISION ENERGY: Low mass vehicles have small light drive trains. Most of the collision energy, lateral load components included, must be absorbed by front structure. Also it is necessary to avoid the deformation of the cabin and intrusion of components. It is necessary to design a deformable front structure which allows distributing energy absorption to all its structural elements. STRUCTURAL CONCEPT: According to crashworthiness and compatibility criteria, it is necessary to integrate an structure which absorbs the energy produced in a collision in the frontal and lateral side of the vehicle, allowing a deformation level enough to avoid an intrusion in the cabin where the passenger are going to stay. The frontal structure should not be aggressive with other vehicles or pedestrians in crashes. And then it is necessary to considered geometrical compatibility with other vehicles. The deformation frontal area after an impact would be possible to be removed if the structure concept designed integrates modularity as well at the structure of the vehicle. OTHER GENERAL CONSIDERATIONS: It is possible to design a better frontal structure of a light car which virtually eliminates over-riding. A good geometrical interaction may result in no significant over-riding, It should be considered in case of reviewing the design philosophy for both front-to- front and front-to-side impact compatibility.

Chapter 8 presents an enhanced passive safety concept based on deformable layers with modulated energy absorption capacity. The most external layer (frontal add-on) is described, characterised and analysed in detail. Its definition is based on the conclusions and results of APROSYS project.

Finally, chapter 9 concentrates on an innovative aspect of the new EVs, such as the maintainability. Reliability of electric vehicles is called in question because the test programs are not able to demonstrate their objectives. This lack of trust has a serious impact on the market that makes the customer lose confidence to the new challenge and its development involves the introduction of this new type of mobility. Currently there are still many test scenarios that have not been tested or are being tested, of which no definitive results are known. At the same time, new innovative components, which are an improvement, do not have enough data to ensure reliability and improve

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WP 2 Report on Design Guidelines for New Concepts of ELTVs

Project nº 266222 Co-financed by European Commission

the performance of previous systems. The most problematic component of the electric vehicle is, no doubt, the battery, while being the most expensive and heavy for all that make the electric vehicle. A challenge is to ensure the safety and durability of it, thus it will provide a pleasant reliability. Common elements between the different types of vehicles do not have a different wear that the one they have when they are subjected to combustion in vehicles, so there is no need to be changed. For example, the tire wear is not influenced, with the exception of in-wheel motor, which results have not been yet studied.

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WP 2 Report on Design Guidelines for New Concepts of ELTVs

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INDEX

1. OBJECTIVES AND SCOPE OF THIS DOCUMENT ______11

2. VEHICLE CATEGORY: GENERAL REQUIREMENTS AND CATEGORY SELECTION ______13 2.1. Introduction ______13 2.2. Requirements for the battery pack of OPTIBODY’s ELTV according to the vehicle category ______13 2.2.1. Vehicle classification ______13 2.3. Legal requirements for the battery pack derived from the vehicle classification ______15 2.4. Discussion on the vehicle category selection ______16

3. STATE-OF-THE-ART BENCHMARKING OF ELTVS AND DERIVED DESIGN GUIDELINES ______17 3.1. Introduction ______17 3.2. Design guidelines for the main vehicle technical features derived from the benchmarking analysis ______17 3.2.1. Nominal power ______17 3.2.2. Energy consumption ______17 3.2.3. Range ______18 3.2.4. Maximum velocity ______18 3.2.5. Total weight ______18 3.2.6. Battery capacity ______18 3.2.7. Battery weight ______18

4. BATTERY TECHNOLOGY ______19 4.1. Introduction to batteries ______19 4.2. Li-ion batteries ______20 4.3. Other types of batteries ______21 4.4. Battery technical features ______21 4.4.1. Six-dimension establishment of battery specifications ______21 4.4.2. Specific energy ______23 4.4.3. Power density ______24 4.4.4. Durability ______26 4.4.5. Cost ______27 4.4.6. Efficiency______28 4.4.7. Safety ______28 4.5. Comparative analysis of batteries vs. gasoline and diesel oil ______29 4.5.1. Graphic visualization of batteries vs. fuel ______30 4.6. Supercapacitors ______31 4.6.1. Battery specifications comparison ______31 4.7. Issued connected with the use of batteries in vehicles: safety ______33 4.8. Battery pack positioning in the vehicle ______34

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4.8.1. Tunnel ______34 4.8.2. Batteries in the trunk: above the rear axle ______36 4.9. Battery pack housing ______39 4.10. Issues connected with the use of batteries in vehicles: standards and tests. ______40 4.10.1. Applicable standards ______40 4.10.2. Standards Setting and Safety Testing Organizations ______41 4.10.3. General Battery Standards ______43 4.10.4. Primary Batteries - General ______43 4.10.5. Lithium Battery Standards ______43 4.10.6. Nickel Metal Hydride Battery Standards ______44 4.10.7. Nickel Cadmium Battery Standards ______45 4.10.8. Lead Acid Battery Standards ______46 4.10.9. Photovoltaic Battery Standards ______49 4.10.10. Safety Standards______50 4.10.11. Automotive Battery Standards ______51 4.10.12. Standards for different UPS Topologies and Methods of Performance Measurement ______52 4.10.13. Software Standards ______52 4.10.14. Ingress Protection (IP) Standards ______53 4.10.15. Battery Monitoring Standards ______53 4.10.16. Battery Recycling and Disposal Standards ______53 4.10.17. Other Related Electrical Standards ______53 4.10.18. Quality Standards ______53 4.11. Charging batteries ______54 4.11.1. Charging infrastructure ______54 4.11.2. Charging power levels ______56 4.11.3. Charging modes for conductive charging ______57 4.11.4. Recently approved European Standard (2012) ______59 4.11.5. Inductive charging ______61 4.12. Design guidelines related to energy storage devices ______62 4.12.1. Specifications according to standards ______62 4.12.2. Weight of the battery pack according to vehicle category ______63 4.12.3. The general requirements for traction batteries ______63 4.12.4. Battery Charging ______63 4.12.5. Battery technical features for BEVs ______63 4.12.6. Battery placement ______64 4.12.7. Positioning in the vehicle ______65 4.12.8. Standards and regulations regarding safety ______66 4.13. References ______66

5. POWERTRAIN ARCHITECTURE FOR ELTVS. ANALYSIS OF VEHICLE PERFORMANCE AND VEHICLE VERTICAL DYNAMICS ______68 5.1. Introduction ______68 5.2. ICE vehicle performance vs. EV (direct drive) performance ______71 5.2.1. Simulation performance of Volvo C30 diesel or electric ______72 5.2.2. Simulation performance of Opel Vivaro diesel or electric ______75 5.3. L7e electric vehicle performance in continuous / peak operation. ______78 5.3.1. Performance comparison______79 5.4. Conclusions on vehicle performance ______89 5.5. In-wheel motors and vehicle vertical dynamics ______90 5.5.1. Introduction ______90 5.5.2. Vehicle vertical dynamics with in-wheel motors: Quarter-car model ______90 5.5.3. Vertical dynamics simulation case: Opel Vivaro ______93 5.5.4. Tire vertical dynamics compensation ______94

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5.6. Conclusions ______95 5.7. Design guidelines derived from the contents in chapter 5. ______96 5.7.1. Regarding vehicle performance ______96 5.7.2. Regarding vehicle vertical dynamics ______96 5.8. References ______97

6. WEIGHT REDUCTION: OPTIONS FOR LIGHTER VEHICLES AND ITS IMPACT ON FUEL SAVING ______99 6.1. Introduction ______99 6.2. Historical vehicle weight trends, US study case ______102 6.2.1. Effectiveness of vehicle weight reduction ______104 6.3. How to reduce vehicle weight. Some strategies ______106 6.3.1. Vehicle weight reduction by lightweight material substitution ______106 6.3.2. Vehicle weight reduction by redesign and secondary weight savings ______110 6.3.3. Vehicle weight reduction by size reduction ______112 6.4. Brief discussion on safety ______115 6.5. Cost of vehicle weight reduction ______115 6.6. Summary on vehicle weight reduction ______118 6.7. Design guidelines derived from the contents in chapter 6. ______118

7. CRASH COMPATIBILITY FOR ELTVS ______120 7.1. Introduction ______120 7.2. Collision mechanics ______120 7.3. Crashworthiness ______121 7.4. Compatibility ______121 7.5. Example: differences between crashworthiness and compatibility ______122 7.6. Frontal and lateral crashes ______125 7.6.1. Frontal crashes ______125 7.6.2. Front to Side impact ______126 7.7. Design guidelines derived from the contents of chapter 7 ______127 7.7.1. Interior geometry ______127 7.7.2. Restraint system ______128 7.7.3. Absorption of collision energy ______128 7.7.4. Structural concept ______128 7.7.5. Other general considerations ______129 7.8. References ______131

8. ADD-ONS AND/OR ENERGY ABSORBERS ______132 8.1. Introduction ______132 8.2. OPTIBODY concept for passive safety. ______132 8.3. The function and behaviour of a stack of energy absorbers in a crash. Model and simulation results ______134 8.3.1. Conceptual model for the comparative crash analysis ______134 8.3.2. Simulation case 1 ______135 8.3.3. Simulation case 2 ______137 8.3.4. Results discussion and conclusion ______139 8.4. Preliminary design guidelines for the frontal add-on ______140 8.4.1. Introduction ______140 8.4.2. Applicable regulations ______141 8.4.3. Frontal add-on position on the chassis ______146 8.4.4. Add-on initial configurations and designs ______149 8.4.5. Impact test simulation ______153 9. MAINTAINABILITY ______156 9.1. Introduction ______156 9.2. Background ______157 9.3. Analysis of electric vehicle fleets ______158 Page 9 of 188

WP 2 Report on Design Guidelines for New Concepts of ELTVs

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9.3.1. United States of America (USA) ______158 9.3.2. US Postal Service ______159 9.3.3. Site Operator Program ______161 9.3.4. Hyundai Santa Fe Fleet in Hawaii ______162 9.3.5. Neighbourhood Electric Vehicle (NEV) ______163 9.3.6. Ford THiNK city ______164 9.3.7. Nissan Hypermini ______166 9.3.8. Canada ______166 9.3.9. UK ______168 9.3.10. Sweden ______169 9.4. European Projects ______170 9.4.1. Project ELCIDIS ______170 9.4.2. Zeus Project ______172 9.4.3. EVD-POST Electric Vehicle Deliveries in Postal Services ______173 9.5. Analysing electric vehicle components ______174 9.5.1. Battery ______174 9.5.2. LCA (Life Cycle Assessment) ______178 9.5.3. Motor AC/DC ______182 9.5.4. In-wheel engine ______183 9.5.5. Inverter ______183 9.5.6. Power converter ______184 9.6. Conclusion and guidelines ______184 9.7. References ______185

ABBREVIATIONS ______188

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WP 2 Report on Design Guidelines for New Concepts of ELTVs

Project nº 266222 Co-financed by European Commission

1. Objectives and scope of this document

This document D2.4 is part of OPTIBODY project WP2: “ANALYSIS OF ELTVs ARCHITECTURE FOR UPDATED BASIS ESTABLISHMENT”.

To achieve its objectives in the project, WP2 is divided into five tasks:

 Task.2.1 Energy storage.  Task.2.2 Powertrain distribution.  Task.2.3 Vehicle structure.  Task 2.4 Maintainability.  Task 2.5 Design.

Deliverable D2.4 is a compendium of the outcome of Tasks 2.1 to 2.5. Deliverable D2.4, together with the rest of the deliverables produced during the development of WP2, form a documentary and reference basis for the development of the rest of the WPs. As stated in the DoW, the content of deliverable should include:

 State of the art benchmarking  New design guidelines as starting point for the other manufacturers.

Dissemination Delivery Del. no. Deliverable name WP no. Nature[1] level[2] date 2.1 Report on energy storage solutions for ELTVs. 2 R PU 4

2.2 Report on powertrains distribution in ELTVs. 2 R PU 6 Frontal and lateral crash compatibility analysis of light 2.3 2 R CO 8 vans with ideal compatible lay-out.

2.4 Design guidelines for new concepts of electric light vans. 2 R PU 9

[1] R = Report, P = Prototype, D = Demonstrator, O = Other [2] PU = Public; PP = Restricted to other programme participants (including the Commission Services); RE = Restricted to a group specified by the consortium (including the Commission Services); CO = Confidential, only for members of the consortium (including the Commission Services).

Figure 1. Deliverables of WP2: ANALYSIS OF ELTVs ARCHITECTURE FOR UPDATED BASIS ESTABLISHMENT

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WP 2 Report on Design Guidelines for New Concepts of ELTVs

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It is important to emphasise that D2.4 is due in month 9th of the project. In consequence, a lot of useful information is expected to be generated in the project after this date.

This new information will be included in the final book that will be produced at the end of OPTIBODY project “D 7.6: Recommended Practices in the Design and Manufacture of Electric Light Trucks and Vans”.

Design guidelines in this report are formulated in three different ways:

 As specified in regulations for the different vehicles categories (chapter 2)  Derived from a benchmarking study (chapter 3)  As consequence of the technical descriptions and considerations of the main vehicle subsystems. A specific section titled “Design guidelines for…” is included at the end of each chapter:

o battery technology (chapter 4) o powertrain architecture (chapter 5) o Total weight (chapter 6) o Crash compatibility (chapter 7) o Add-ons and energy absorbers (chapter 8) o Maintainability (chapter 9)

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WP 2 Report on Design Guidelines for New Concepts of ELTVs

Project nº 266222 Co-financed by European Commission

2. Vehicle category: general requirements and category selection

2.1. Introduction

This chapter includes a summary of the contents in Deliverable 2.1 REPORT ON ENERGY STORAGE SOLUTIONS FOR ELTVS.

Basic contents are the requirements for the battery pack imposed by the vehicle homologation category, types and technical features of batteries, positioning in the vehicle and applicable standards.

2.2. Requirements for the battery pack of OPTIBODY’s ELTV according to the vehicle category

2.2.1. VEHICLE CLASSIFICATION

The type of vehicle studied in OPTIBODY project can be included into different categories according to the Framework Directive 2002/24/EC. Each vehicle category imposes different specifications mainly regarding the total vehicle mass and maximum power. It is a decision of the consortium to adopt a specific category.

At the time of writing this document, vehicle category L7e has been selected.

The basic definitions of vehicle categories are given in the next paragraphs:

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Three-wheeled vehicle (L5e)

A motor vehicle including three symmetrically placed wheels, equipped with an engine with cylinder capacity of more than 50 cm3 in the case of an internal combustion engine, or whose maximum structural speed is higher than 45 km/h.

Light quadricycles (L6e)

Light quadricycles (L6e) are defined by Framework Directive 2002/24/EC as: "motor vehicles with four wheels (...) whose unladen mass is not more than 350 kg, not including the mass of the batteries in case of electric vehicles, whose maximum design speed is not more than 45 km/h, and:

(i) whose engine cylinder capacity does not exceed 50 cm3 for spark (positive) ignition engines, or

(ii) whose maximum net power output does not exceed 4 kW in the case of other internal combustion engines, or

(iii) whose maximum continuous rated power does not exceed 4 kW in the case of an electric motor.

These vehicles shall fulfil the technical requirements applicable to three-wheel mopeds of category L2e unless specified differently in any of the separate directives".

Therefore, in many European countries such as France, Italy, Belgium, Spain and the Netherlands, light quadricycles can be driven without an automobile driver’s licence (category B).

Heavy quadricycles (L7e)

Quadricycles (L7e), also referred to as Heavy Quadricycles, are defined by Framework Directive 2002/24/EC as motor vehicles with four wheels "other than those referred to (as light quadricycles), whose unladen mass is not more than 400 kg (category L7e) (550 kg for vehicles intended for carrying goods), not including the mass of batteries in the case of electric vehicles, and whose maximum net engine power does not exceed 15 kW.

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These vehicles shall be considered to be motor tricycles and shall fulfil the technical requirements applicable to motor tricycles of category L5e unless specified differently in any of the separate Directives".

Light commercial vehicles (N1)

Category N1: Vehicles designed and constructed for the carriage of goods and having a maximum mass not exceeding 3,5 tonnes.

2.3. Legal requirements for the battery pack derived from the vehicle classification

The requirements for the battery pack imposed by the vehicle classification are:

For vehicles L7e

No direct requirements in terms of weight, capacity, etc.

As the total allowed power is only 15 Kw, the total vehicle weight should be kept as small as possible to increase vehicle performance and in consequence, the weight of the battery pack must be optimised.

For vehicles N1

No direct requirements in terms of weight, capacity, etc.

As the total vehicle weight is 3.500 Kg, the unladen vehicle weight should be kept as small as possible (and in consequence, the battery pack weight), to allow more payload.

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2.4. Discussion on the vehicle category selection

OPTIBODY project will focus on L7e vehicles. The main reason for the selection of L7e category is that this vehicle category is less regulated than N1 vehicles in terms of crash behaviour. Details about applicable standards can be found in D1.1 Summary of regulations applicable to a light van in different markets with expected revisions.

Therefore, given the maximum allowable power of 15 kW, it has been detected that many car manufacturers offer EVs homologated inside this category. Given the state of the art in many of the technologies involved in EVs (i.e. batteries), it is easier to design and manufacture low power vehicles.

In consequence, a lot of work on passive safety is needed in L7e category, being this one the main objective of OPTIBODY project.

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WP 2 Report on Design Guidelines for New Concepts of ELTVs

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3. State-of-the-art benchmarking of ELTVs and derived design guidelines

3.1. Introduction

Deliverable D 2.2: Report on powertrains distribution in ELTVs, 8section 3.5) includes a detailed benchmarking database for the analysis of electric light trucks and vans in the market. This chapter presents the results of that benchmarking work, expressed in the way to be taken as basis for the design of new ELTVs.

3.2. Design guidelines for the main vehicle technical features derived from the benchmarking analysis

3.2.1. NOMINAL POWER

The ELTVs analysis in Deliverable 2.2 (section 3.5) shows that, as nominal power is fixed by regulations, any new ELTV must respect specific values:

 Up to 4 kW for L6e category  Up to 15 kW for L7e  No limitation for N1 category.

3.2.2. ENERGY CONSUMPTION

The average value for all vehicles included in the database is around 140 kWh/km.

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3.2.3. RANGE

The average value for all vehicles included in the database is around 82 km. Some vehicles “declare” 100 km and just a few of the given greater range values.

3.2.4. MAXIMUM VELOCITY

Standards fix the maximum speed only for L6e category. For them, the maximum velocity is limited to 45 km/h.

The average value for all vehicles in the database is around 50 km/h. Some L7e vehicles “declare” 60 km/h, some declare 80 km/h.

3.2.5. TOTAL WEIGHT

Standards regulate the weight of vehicles in the following way:

 L6e: unladen mass not more than 350 kg, not including the mass of the batteries in case of electric vehicles.  L7e: unladen mass not more than 400 kg or 550 kg for vehicles intended for carrying goods, not including the mass of batteries in the case of electric vehicles.  N1: The total vehicle weight must be under 3.5 tons (including the payload).

The average value for all vehicles in the database is around 725 kg.

3.2.6. BATTERY CAPACITY

The average value for all vehicles in the database is around 11 kWh. Values go from 9 to 15 kWh.

3.2.7. BATTERY WEIGHT

The average value for all vehicles in the database is around 230 kg. Values go from 160 to 380kg.

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WP 2 Report on Design Guidelines for New Concepts of ELTVs

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4. Battery Technology

4.1. Introduction to batteries

A battery is an electric instrument which can give current in a circuit, at almost the same voltage in every condition. It is made by a series of elementary cells. The voltage of any cell is the potential difference generated from two different metals; one is used like anode (positive pole) and the other one like cathode (negative pole). The voltage of a battery is the sum of the single potential difference of each cell. A battery, over cathode and anode, needs also a salt bridge and an electrolyte, to close the circuit and complete oxide-reduction reaction. This electrolyte can be liquid (like lead batteries) or solid (like alkaline batteries).

Today batteries are the main cost in an electric car and also the heaviest and bulky mechanical part. The study of batteries and their choice is fundamental in the design of those vehicles.

The general requirements for traction batteries are, as for all battery applications: low cost, long life (more than 1000 cycles), low self-discharge rates (less than 5% per month) and low maintenance are basic requirements for all applications. But traction batteries have added requirements: generally operate in very harsh operating environments and must withstand wide temperature ranges (-30°C to +65°C) as well as shock, vibration and abuse. Also, low weight is however essential for high capacity batteries used in electric vehicles (EV) and hybrid electric vehicles (HEV) for passenger. Protection circuits are also essential for batteries using non-lead acid chemistries.

The most used batteries in means on road in order of their efficiency are lead-acid, Ni-MH (Nickel- metal hybrid) and Li-ion (Lithium-ion) batteries. The most important features for batteries are:

 Specific energy

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 Specific power  Durability  Cost  Efficiency  Safety

4.2. Li-ion batteries

Li-ion batteries are today the most balanced technology in terms of performance-cost ratio for application in EVs. Lithium ion batteries are a type of rechargeable battery in which a lithium metal ion extracted from the anode moves to the cathode and intercalates with it during discharge (and vice versa during charging). Due to their high energy density, absence of memory effect and limited loss of charge, Lithium ion batteries are widely used in consumer electronics. Voltage, capacity, lifetime, and safety of a lithium ion battery are critically dependent on the choice of materials for cathode, anode and electrolyte. For batteries used in portable devices the anode is typically made from carbon (graphite), the cathode is a metal oxide (e.g. LiCoO2), and the electrolyte is a lithium salt. This way, energy densities of more than 200 Wh/kg can be achieved today.

Lithium ion batteries are currently also considered the best option for transportation batteries to be used in plugin hybrid and full electrical vehicles. However for this application a new generation of battery system will be required providing higher energy density, lower cost and use of abundant materials. The cathode material of choice (as it is providing higher safety) may be LiFePO4, which in its natural form is a mineral with poor electronic and ionic conductivity, however if synthetically shaped on the nanoscale it may provide appropriate properties. Also for the anode, nanostructured materials are considered, e.g. hard carbon or Si-C nano-composites which can be expected to increase the energy density by 20-30 %.

Technology paths towards even higher energy densities (as desired for fully electric traction) may include Lithium air batteries, whereas higher power densities (required for hybrid power trains) may be expected from Lithium ion batteries using nano-sized titanate electrodes.

The experts agreed that two paths should be followed to advance the basic principles of batteries for EV, (a) research in even more advanced, next generation (not necessarily Li) battery systems, and (b) improvement of the available Li ion battery by development of new or newly structured electrode materials, novel electrolytes and other components.

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4.3. Other types of batteries

Other new technologies are arising. The more interesting are listed below.

 Nickel-zinc batteries (NiZn)  Molten salt batteries  Sodium aluminiumchloride (Zebra) batteries.  Vanadium redox batteries  Aluminium-air batteries

4.4. Battery technical features

4.4.1. SIX-DIMENSION ESTABLISHMENT OF BATTERY SPECIFICATIONS

Technical issues

Competing battery technologies can be compared along six dimensions:

 safety  life span (measured in terms of both the number of charge and discharge cycles and overall battery age)  performance (peak power at low temperatures, state of charge measurement and thermal management)  recharging time  specific energy (how much energy can be stored per kilogram of mass)  cost

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High energy density

High power Fast charging

Cycle life Safety

Cost

Figure 2. Six-dimension graph used to establish battery characteristics according to vehicle type and use

HV, PHEV, BEV

High energy density

HEV Fast charging High power

PHEV

Cycle life Safety BEV

Cost

Figure 3. According to the different vehicle technology

2010 2015 2020 2030 Application Advanced HEV PHEV Advanced PHEV BEV

Performance 1 x1.5 x3 x7 Energy density (Whkg-1) 70 100 200 700 Specific power (Wkg-1) 2000 2000 2500 1000 Cost ($/kWh) 1220 370 240 60

Chart 1. Required performance and cost of batteries with respect to battery-powered vehicle applications

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4.4.2. SPECIFIC ENERGY

Specific energy indicates how much energy can be stored into a battery when it is completely charged. The value of energy is divided by the weight. In full-electric cars, this characteristic is very important, because if this value is high, battery can store enough energy in a little battery (light weight; Figure 4).

Figure 4. Batteries specific energy (minimum and maximum values found in references) [22], [23], [24]

Supposing that a full-electric car needs about 10 kWh of energy, the table below (Chart 2) shows battery’s weight needed to have approximately 100 km of autonomy (energy density is a value really important in electric cars).

Batteries Weight (kg) Lead-acid 285 Ni-Cd 200 Ni-MH 130 Li-ion 70

Chart 2. Battery weight of a 10 kWh car

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The advantage of Li-ion batteries is very high; being the lithium is the lightest metal. Less than the half of the weight used with the lead-acid battery is required with Ni-MH batteries; for example, using a 200 kg Li-ion batteries pack, autonomy can increase at near 300 km (only urban use).

Figure 5. Energy density (volumetric and gravimetric)

4.4.3. POWER DENSITY

Batteries can’t give all the power needed by a big electric motor, because they had an internal resistance that reduces battery efficiency if discharge rate is too high. This is because chemical reactions involved are slow. This value is almost constant for the same category of battery.

Power density is the maximum power that a battery can supply with a good efficiency divided by battery weight. This is an important property in particular for hybrid cars, because there are small batteries in them, which often cannot give enough power to big electric motors (Figure 6). The problem is not so important in full-electric cars, because they use very big batteries (high autonomy requested) and little motors (for city use only).

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Figure 6. Electric power density (minimum and maximum values in references) [22], [23], [24]

Only Ni-MH batteries have a very higher performance than the other, so this battery is very spread in hybrid cars. The chart below (Chart 3) shows weight supposing the need of 25 kW to move the car (the value is enough for a small city car).

Batteries Weight (kg) Lead-acid 145 Ni-Cd 170 Ni-MH 50 Li-ion 80

Chart 3. Battery weight to supply 25 kW electric motor

Comparing this table with the one in the other chapter, it is evident that the weight due to ensure enough range is higher than to give right power to the motor. For this reason, Ni-MH batteries which have much more power density, were been supplanted by Li-ion ones. The weight is in the two cases, so, if most power more or less the same is needed, the car may have most autonomy.

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4.4.4. DURABILITY

Durability measures how much complete charge and discharge cycles a battery can endure without lose most of its performances. Battery durability is the most important disadvantage of electric cars, because their substitution cost is almost the half price of the entire car.

Figure 7. Battery durability (minimum and maximum values in references) [22], [23], [24]

The differences between these kinds of batteries are very small, so it is important to remember that Li-ion batteries costs much more than the others. Real durability of batteries is larger, because it increases if they are not completely discharged every time.

The table below shows batteries durability, in years, if they are fully recharged one time a week (Chart 4). This assumption is perhaps not fully realistic, but at least it enables to compare in an homogeneous way the four battery technologies under study.

Battery Durability (years) Lead-acid 7,5 Ni-Cd 19 Ni-MH 19 Li-ion 11,5

Chart 4. Battery (in years) supposing a complete charge every week

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Lead-acid durability is very low, but this kind of battery is quite cheap, so a change of them would not be very expensive. Ni-Cd and Ni-MH battery have the same durability of the other parts of the car. Some manufacturer guarantees their Li-ion batteries for 12 years.

4.4.5. COST

The cost of battery is very important in an electric car, because the higher price of a full-electric car than a gasoline one is almost due to this cost. The graph below (Figure 8) shows specific cost of every kind of battery. The values are given by the cost of the battery divided by its weight: it is quite the same in every battery family.

Figure 8. Battery specific cost (minimum and maximum values in references) [22], [23], [24]

Lead-acid batteries (the cheapest typologies) have lower performance than the others, so a bigger weight of them is needed. The chart below (Chart 5) shows the total cost of batteries to move a 25 kW 100 km of range city car.

Battery Cost (€) Lead-acid 2200 Ni-Cd 10000 Ni-MH 7800 Li-ion 12000

Chart 5. Battery total cost for a 25 kW-100 km range citycar

Lead-acid batteries are the cheapest in absolute, but due to their poor durability, it is necessary to replace them at least one time during vehicle life. Ni-MH batteries are cheaper than Ni-Cd ones, because their specific cost is similar, but specific energy is higher. Today the Ni-Cd batteries are totally replaced by the other kind.

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4.4.6. EFFICIENCY

All chemical reactions disperse an amount of energy, so all batteries do not return all the energy that they have received during the charge. The efficiency is the relationship between the energy stored in a battery and the amount of energy that is given back by them.

A perfect battery may have the 100% efficiency, so it would store all the energy without loss. The graph below (Figure 9) shows the efficiency of the four kinds of batteries considered in the treatment.

Figure 9. Battery efficiency (minimum and maximum values in references) [22], [23], [24]]

The efficiency is similar for all kind of batteries; in lead-acid ones, it depends mainly on the speed of charging (if it is high, the efficiency decrease). Li-ion batteries have the best efficiency, so they need less electric energy than the other ones. These batteries are quite expensive, but electricity cost to recharge them is low.

4.4.7. SAFETY

Speaking about batteries it is possible to consider two kinds of safety aspects:

 User safety  Environmental safety

In particular:

 Lead-acid batteries are safe for users only if they are correctly charged; otherwise, if they are charged too much fast, they could explode. These batteries also contain acid sulphuric liquid, so, in case of mechanical stresses, they may leak (for example in case Page 28 of 188

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of crash). For this reason today almost all lead-acid batteries contain gel electrolyte. Lead-acid batteries contain lead, cadmium and sulphuric acid, which are very dangerous substances for environment and toxic for human.  Ni-Cd batteries contain cadmium, which is very toxic. For this reason now it is forbidden to produce this type of battery (except little batteries).They are replaced by Ni-MH ones, less toxic for environment. If correctly charged, Ni-MH batteries have low explosion risk (also if overcharged), and they have bigger stress resistance. In case of fire, they are safer than lead-acid ones, because gasses generation is lower, so internal pressure does not increase very much. Although Ni-MH batteries are less toxic than Ni-Cd ones, they must be recycled, because they contain metal.  Li-ion batteries have chemical reaction less stable than the other kinds, so their safety is lower. These batteries may keep fire when their temperature is too much high or they are exposed to fire or stored in a hot place. In USA, nearly 7000 accidents like that occurred in last year using cell phone or laptop computer. In case of crash, however, Li-ion batteries are safer, because they do not generate gasses which may increase too much internal pressure. Li-ion batteries are not much toxic, but today, in Italy, all batteries have to be recycled. Li-ion batteries die quickly if operated at 60 oC and explode at 80 oC.

Although there isn’t a particular regulatory, car producers subject their cars to the some test of the other ones. Usually fire risk is reduced, because there isn’t any fuel tank.

4.5. Comparative analysis of batteries vs. gasoline and diesel oil

ICE vehicle use gasoline or diesel oil to store energy. EVs use batteries. Concerning the battery, a summary of its main definition parameters is given in Chart 6. It can be observed that the gasoline has an energy density, power density, etc. two orders of magnitude greater than batteries.

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Pb/ac Ni/Cd NiHM Li-Ion Li/p Na/NiCl2 Objetives USABC GASOLINE Specific energy (wh/kg)) 35-40 55 70-90 125 155 80 200 14.256 Specific power (w/kg)) 80 120 200 260 315 145 400

3 Energy density (wh/m ) 75 90 90 200 165 130 300 9.694 Life cycles (number of 300 1000 600 +600 +600 600 1000 recharge cycles) Recharge time (h) 6-8 6-8 6 4-6 4-6 4-6 3-6

Autonomy (km) 75 100 200 200 250 200 250

Cost ( € / kwh) 100 400 550 - - - <90

Chart 6. Main characteristics of the gasoline compared to batteries

4.5.1. GRAPHIC VISUALIZATION OF BATTERIES VS. FUEL

The quantitative analysis presented in the previous paragraphs helps to better understand the content and significance of the battery/fuel comparative diagrams normally used. The next figures present the same information in a graphic way.

terrestrial propulsion

thermal engines acceleration

1000

autonomy

Figure 10. Comparative graph battery-fuel for vehicle traction

Another way to illustrate the same facts is the Ragone plot. The Ragone chart (also called Ragone plot) is a chart used for performance comparison of various energy storing devices. On such a chart the values of energy density (in Wh/kg) are plotted versus power density (in W/kg). Both axes are logarithmic, which allows comparing performance of very different devices (for example extremely high, and extremely low power).

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Figure 11. Ragone chart showing energy density vs. power density for various energy-storing devices

4.6. Supercapacitors

The supercapacitors are condensers which can store a big amount of energy, so it is possible to replace batteries with them. They have a very high durability (about one million of cycles) and a big efficiency, because they do not use any chemical reaction; self-discharge is very high (Figure 12).

Figure 12. A commercial 58 F-15 V supercapacitor

Supercapacitors power density is an order bigger than electrochemical batteries, so they can supply electrical energy to big engines without increasing the weight (near 3-5 kW/kg). The principal disadvantage of these devices is the rather small energy that they can store: it is 10-100 times lower than normal batteries.

4.6.1. BATTERY SPECIFICATIONS COMPARISON

Chart 7 collects specifications about main marketed electric vehicles. Page 31 of 188

Max Battery Weight Stored energy Range Charging Max speed Accel. 0- Brand Model Year in Year out Battery type power Price ($) Notes weight (kg) (kg) (kWh) (km) time (h) (km/h) 100 (s) (kW) FIAT Panda Elettra 1990 1995 ? 400 1150 17 13 70 8

GM EV1 1996 2003 Pb-acid 1400 111 130 8

GM EV2 1996 2003 NiMH 1319 130

Smart ED 2011 Li-ion 1000 16.5 135 8 30 120 18

Tesla Roadster 2008 Li-ion 1135 240 240 185 200 3.9

Mitsubishi i MiEV Citroën C0 2011 Li-ion 1080 0.185 0.5 30 51000 130 15.9

Peugeot i-On Nissan Leaf 2011 Li-ion 1531 24 0.5 80 150 9.9

Batteries can be Renault Fluence 2012 Li-ion 1543 22 0.5 70 135 11 substituted

Tata Indica Vista 2011 Polymer Li-ion 26.5 257 55 9000 100 10

Li-ion Westfield iRacer 2011? 770 23 120 185 5 phosphate Chevrolet Volt E-REV, current is Opel Ampera 2011 Li-ion 197 1715 16 56 111 43000 hybrid Vauxhall Ampera LCC Lightning GT 2012 Li-titanate 22 240 5-15 300 200 5

Renault ZOE 2012 159 0.5 60 135 8

Audi R8 E-Tron 2012 Li-ion 241 230 4 in-wheel motors 4.8

Audi A3 E-Tron 2012 Li-ion 26.5 140 4-9 100 11

Ford Focus EV 2012 23 160 150 37000 137

Tesla Model S 2012 Li-ion 260-480 3-5 57400

Volkswagen Golf blue-e-motion 2013 Li-ion 150 85 140

NaAlCl4 or Li- Think Global Th!nk City 2008 2011 1038 24-23 160 34 110 ion

Chart 7. Power to weight ratio of electric car

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4.7. Issued connected with the use of batteries in vehicles: safety

Nowadays Li-ion batteries are by far the prevailing solutions. However they bring together serious safety concerns. If overheated or overcharged, Li-ion batteries may suffer thermal runaway and cell rupture. In extreme cases this can lead to combustion. They can even rupture, ignite, or explode when exposed to high temperature. For example, the all-electric Tesla Roadster which has 6,831 Li-ion batteries packed under its hood is equipped with a cooling system, which ensures the batteries do not overheat. It also regulates the speed of the flow of ions to keep them from re-charging or draining too quickly.

Serious concerns come also in the case of accident. There is supported evidence of serious risks in the case of crash, especially side and rear impacts.

Standard 12 Volt and 24 Volt automotive battery circuits rely on the vehicle chassis as the ground (earth) return circuit. This practice is acceptable when no lethal voltages are involved but not for high voltage batteries used in EV and HEV applications. If the battery allocation is not properly designed, someone could easily become the conduit between any of the exposed the high voltage terminals (on the battery, the motor and its controller) and the chassis.

EV and HEV battery circuits should therefore use isolated battery busses for both the positive and negative sides of the battery. This is also an essential operating safety feature since accidental loss of isolation could subject the driver or emergency services to hazardous voltages or causes a dangerous short circuit of the battery. In case of isolation failure or accidental damage, ground fault monitoring which detects current leakage from the battery or inertia switches which detect high G deceleration due to an accident, should automatically disconnect the battery.

Battery placement is therefore critical. The battery pack is heavy and voluminous. In passenger cars typical, if only possible, solutions are:

1. Under the bonnet/hood 2. In the tunnel

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3. In the trunk/luggage compartment

Notice that the assumption is made that all the battery assembly is kept in a single pack. This is to avoid further electric complication.

Battery placement influences:

• Dynamics: placement of the masses • Crash: especially side and rear crash tests • Production: avoid, as much as possible, modification in the integration process with respect to parent ICE vehicles • Economics: in the case of hybrid or vehicles derived from ICE, use the same platform

4.8. Battery pack positioning in the vehicle

4.8.1. TUNNEL

The battery pack is set in the tunnel, where usually is place for the transmission shaft to the rear differential in a rear-wheel traction or 4WD system (Figure 13) [18].

Placing the battery in the tunnel offers the following advantages:

• Dynamics: masses are distributed along the centre axis of the vehicle and in the lowest position • Crash: batteries are in a “safe” place with respect to side crash • Production: batteries are assembled with the drivetrain, no need to package batteries at the end of the assembly process • Economics: there are just a few changes on the chassis

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Figure 13. Placement of the batteries in the tunnel

Safety issues have been addressed by various manufacturers. Volvo C30 electric car has been tested and the safety level of this solution has been demonstrated (Figure 14) [18].

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Figure 14. Volvo C30 offset front-crash: the battery compartment in the tunnel performed very well and no damage occurred

4.8.2. BATTERIES IN THE TRUNK: ABOVE THE REAR AXLE

The battery pack is set above the rear axle, behind the second row of seats (Figure 15). In the case of a freight transport vehicle it would be behind the cabin.

Placing the battery in the trunk offers the following advantages:

• Dimensions: there are few limitations on the size of the battery pack and its shape; several configurations of the battery pack can be adopted • Crash: batteries are placed in a secure place with respect to side crash • Economics: limited changes in the chassis; the pack is installed at the end of the assembly line in the trunk

Drawbacks are the following:

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• Dynamics: suspensions must be reinforced since a higher mass is standing on the rear axle; moreover, the dynamic behaviour of the vehicle will be affected by a different disposition of the masses • Production: batteries are separated from the drivetrain; therefore, they are installed at the end of the assembly line in the trunk, requiring special areas in the plant for such installation and dedicated work-force

Figure 15. Placement of the batteries above the rear axle

Again there are examples from Volvo demonstrating that the battery pack can be securely protected avoiding serious perils (Figure 16).

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Figure 16. Volvo V50 rear impact at 89 km/h: no noticeable damage to the battery pack.

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4.9. Battery pack housing

The battery pack housing is a key safety issue. No matter the type of battery used in the car, they contain chemical substances that can be potentially very pollutant and dangerous.

Protection against leakage in crashes is done by housing the battery pack in a case. An example of this case (in green) can be seen in Figure 16. This case is a specific design of each car manufacturer.

Applicable standards are:

 SAE J1766 Recommended Practice for Electric and Hybrid Electric Vehicle Battery Systems Crash Integrity Testing (Work in progress)  SAE J1797 Recommended Practice for Packaging of Electric Vehicle Battery Modules

The weight of the housing box needs to be accounted. A recent research project, developed by the Fraunhoffer Institutes [19], have developed a crash-safe battery housing, made of composite materials, that can withstand a crash, (simulated as a ten- fold gravitational acceleration). This box weights approximately only 10% of the battery pack weight.

Concerning the precautions to be taken after a crash by the users, the American National Highway Traffic Safety Administration (NHTSA) issued a statement [20] with some recommendations, after a crash test performed to a Chevrolet Volt that resulted in a fire. They are listed below:

 Consumers are advised to take the same actions they would in a crash involving a gasoline-powered vehicle — exit the vehicle safely or await the assistance of an emergency responder if they are unable to get out on their own, move a safe distance away from the vehicle, and notify the authorities of the crash.  Emergency responders should check a vehicle for markings or other indications that it is electric-powered. If it is, they should exercise caution,

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per published guidelines, to avoid any possible electrical shock and should disconnect the battery from the vehicle circuits if possible.  Emergency responders should also use copious amounts of water if fire is present or suspected and, keeping in mind that fire can occur for a considerable period after a crash, should proceed accordingly.  Operators of tow trucks and vehicle storage facilities should ensure the damaged vehicle is kept in an open area instead of inside a garage or other enclosed building.  Rather than attempt to discharge a propulsion battery, an emergency responder, tow truck operator, or storage facility manager should contact experts at the vehicle's manufacturer on that subject.  Vehicle owners should not store a severely damaged vehicle in a garage or near other vehicles.  Consumers with questions about their electric vehicles should contact their local dealers.

4.10. Issues connected with the use of batteries in vehicles: standards and tests.

4.10.1. APPLICABLE STANDARDS

National and international standards organisations were set up to facilitate trade by encouraging greater product interoperability and compatibility as well as setting standards for acceptable product safety, quality and reliability.

Below are listed some of the most common standards applicable to battery applications and some of the organisations who issue them and or carry out quality assurance and conformance testing. In Europe, European standards are gradually being adopted in replacement of the previous national standards.

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4.10.2. STANDARDS SETTING AND SAFETY TESTING ORGANIZATIONS

AENOR Asociación Española de Normalización y Certificación (Spain) ANSI American National Standards Institute sponsored by NEMA AS Australian Standard ASE Association Suisse des Electriciens (Swiss) ASQC American Society for Quality Control ASTM American Society for Testing and Materials ATEX Explosive Atmospheres (Safety directive) BCI Battery Council International (Publishes Automotive Battery Standards) BS British Standards CARB California Air Resources Board (Automotive Emission Standards) CE Conformance with EU directives CEN European Committee for Normalisation (Standards Committee) CENELEC European Committee for Electrotechnical Standardisation CISPA International Special Committee on Radio Interference CODATA Committee on Data for Science and Technology (Committee of ICSU) CSA Canadian Standards Association DEF Defence Standards (UK) DEMKO Danmarks Electriske Materielkontrol (Denmark) DIN Deutsches Institut für Normung (German Institute for Standardisation) ECE Economic Commission for Europe regulations. EIA Electronics Industry Association (USA) EN European Norms (Standards) FCC Federal Communications Commission (USA) FIMKO Finnish Electrical Inspectorate FIPA Foundation for Intelligent Physical Agents (Interoperability standards) GB Guo Biao = National Standard (People's Republic of China) HSE Health & Safety Executive (UK) ICSU International Council for Science IEC International Electrotechnical Commission IEE Institution of Electrical Engineers (UK) IEEE Institute of Electrical and Electronics Engineers (USA) IMQ Instituto Italiano del Marchio de Qualitá Page 41 of 188

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IP Ingress Protection ISO International Standards Organisation ITU International Telecommunications Union JIS Japanese Industrial Standard KEMA Keuring van Elektrotechnishe Materialen (Netherlands) KIST Korean Institute of Standards and Technology MIL Military Standards (USA) MISRA Motor Industry Software Reliability Association (UK) MVEG Motor Vehicle Emission Group (EU Emission standards) NAMAS National Measurement Accreditation Service (UK Calibration) NEMA National Electric Manufacturers Association (USA) NEMKO Norges Electriske Materiellkontroll (Norway) NF Norme Française (France) NFPA National Fire Protection Association (USA) NIJ National Institute of Justice (USA) OSHA US Department of Labor - Occupational Safety & Health Administration OVE Osterreichischer Verband für Elektrotechnik (Austria) PowerNet Automotive 42 Volt Battery Standard RESNA Rehabilitation Engineering & Assistive Technology Society of North America SAE Society of Automotive Engineers (USA) SEMKO Svenska Elektriska Materielcontrollanstalten (Sweden) SEV Schweitzerischer Elektrotechnische Verein (Swiss) STANAG NATO Standards Agreements STRD DTI Standards and Technical Regulations Directorate (UK) TIA Telecommunications Industry Association (USA) TR Technical Report (Used by IEC) TÜV TÜV Rheinland Group (TUV - Technical Inspection Asssociation) UKAS UK Accreditation Service (Assessment of test services)/(Calibration) UL Underwriters Laboratories Requirements (USA) USABC United States Advanced Battery Consortium USNEC United States National Electrical Code UTE Union Technique de l'Electriciteé (France) VDE Verband Deutscher Elektrotechniker (Germany)

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4.10.3. GENERAL BATTERY STANDARDS

IEC 60050 International electrotechnical vocabulary. Chapter 486: Secondary cells and batteries. IEC 60086-1, BS 387

4.10.4. PRIMARY BATTERIES - GENERAL

IEC 60086-2, BS Batteries - General ANSI C18.1M Portable Primary Cells and Batteries with Aqueous Electrolyte - General and Specifications ANSI C18.2M Portable Rechargeable Cells and Batteries - General and Specifications ANSI C18.3M Portable Lithium Primary Cells and Batteries - General and Specifications UL 2054 Safety of Commercial and Household Battery Packs - Testing IEEE 1625 Standard for Rechargeable Batteries for Mobile Computers USNEC Article 480 Storage Batteries ISO 9000 A series of quality management systems standards created by the ISO. They are not specific to products or services, but apply to the processes that create them. ISO 9001: 2000 Model for quality assurance in design, development, production, installation and servicing. ISO 14000 A series of environmental management systems standards created by the ISO. ISO/IEC/EN 17025 General Requirements for the Competence of Calibration and Testing Laboratories

4.10.5. LITHIUM BATTERY STANDARDS

BS 2G 239:1992 Specification for primary active lithium batteries for use in aircraft BS EN 60086-4:2000, IEC 60086-4:2000 Primary batteries. Safety standard for lithium batteries BS EN 61960-1:2001, IEC 61960-1:2000 Secondary lithium cells and batteries for portable applications. Secondary lithium cells

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BS EN 61960-2:2002, IEC 61960-2:2001 Secondary lithium cells and batteries for portable applications. Secondary lithium batteries 02/208497 DC IEC 61960. Ed.1. Secondary cells and batteries containing alkaline or other non-acid electrolytes. Secondary lithium cells and batteries for portable applications 02/209100 DC IEC 62281. Ed.1. Safety of primary and secondary lithium cells and batteries during transport BS G 239:1987 Specification for primary active lithium batteries for use in aircraft BS EN 60086-4:1996, IEC 60086-4:1996 Primary batteries. Safety standard for lithium batteries UL 1642 Safety of Lithium-Ion Batteries - Testing GB /T18287-2000 Chinese National Standard for Lithium Ion batteries for mobile phones ST/SG/AC.10/27/United Nations recommendations on the transport of dangerous goods

4.10.6. NICKEL METAL HYDRIDE BATTERY STANDARDS

BS EN 61436:1998, IEC 61436:1998 Secondary cells and batteries containing alkaline or other non-acid electrolytes. Sealed nickel-metal hydride rechargeable single cells BS EN 61808:2001, IEC 61808:1999 Secondary cells and batteries containing alkaline or other non-acid electrolytes. Sealed nickel-metal hydride button rechargeable single cells BS EN 61951-2:2001, IEC 61951-2:2001 Secondary cells and batteries containing alkaline or other non-acid electrolytes. Portable sealed rechargeable single cells. Nickel-metal hydride BS EN 61951-2:2003 Secondary cells and batteries containing alkaline or other non- acid electrolytes. Portable sealed rechargeable single cells. Nickel-metal hydride 96/216533 DC IEC 1808. Sealed nickel-metal hydride button rechargeable single cells (IEC Document 21A/207/CD) 97/204158 DC IEC 1441. Secondary cells and batteries containing alkaline or other non-acid electrolytes. User-replaceable batteries containing more than one sealed nickel-metal hydride rechargeable cell for consumer electronic applications (21A/212/CD)

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00/246138 DC BS EN 61436 Ed 2. Sealed nickel-metal hydride rechargeable single cells (IEC Document 21A/303/CD)

4.10.7. NICKEL CADMIUM BATTERY STANDARDS

BS EN 1175-1:1998 Safety of industrial trucks. Electrical requirements. General requirements for battery powered trucks BS EN 2570:1996 Nickel-cadmium batteries. Technical specification BS EN 2985:1996 Nickel-cadmium batteries of format A type BS EN 2986:1996 Nickel-cadmium batteries of format B type BS EN 2987:1996 Nickel-cadmium batteries of format C type BS EN 2988:1996 Nickel-cadmium batteries of format D type BS EN 2991:1996 Nickel-cadmium batteries of format E type BS EN 2993:1996 Nickel-cadmium batteries of format F type BS EN 60285:1995, IEC 60285:1993 Alkaline secondary cells and batteries. Sealed nickel-cadmium cylindrical rechargeable single cells BS EN 60622:1996 Sealed nickel-cadmium prismatic rechargeable single cells BS EN 60622:2003 Secondary cells and batteries containing alkaline or other non-acid electrolytes. Sealed nickel-cadmium prismatic rechargeable single cells BS EN 60623:1996, IEC 60623:1990 Vented nickel-cadmium prismatic rechargeable single cells BS EN 60623:2001, IEC 60623:2001 Secondary cells and batteries containing alkaline or other non-acid electrolytes. Vented nickel-cadmium prismatic rechargeable single cells BS EN 60993:2002 Electrolyte for vented nickel-cadmium cells BS EN 61150:1994, IEC 61150:1992 Alkaline secondary cells and batteries. Sealed nickel-cadmium rechargeable monobloc batteries in button cell design BS EN 61440:1998, IEC 61440:1997 Secondary cells and batteries containing alkaline or other non-acid electrolytes. Sealed nickel-cadmium small prismatic rechargeable single cells BS EN 61951-1:2001, IEC 61951-1:2001 Secondary cells and batteries containing alkaline or other non-acid electrolytes. Portable sealed rechargeable single cells. Nickel-cadmium

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BS EN 61951-1:2003 Secondary cells and batteries containing alkaline or other non- acid electrolytes. Portable sealed rechargeable single cells. Nickel-cadmium BS EN 62259:2004 Secondary cells and batteries containing alkaline or other non-acid electrolytes. Nickel-cadmium prismatic secondary single cells with partial gas recombination 94/216281 DC Guide to the equipment manufacturers and users of alkaline secondary cells and batteries on possible safety and health hazards. Part 1:Nickel-cadmium. (21A/163/CD) 96/203612 DC IEC 1914. Technical report type 2. Alternative publication for vented nickel-cadmium prismatic rechargeable single cells (IEC Document 21A/186/CDV) 98/203520 DC IEC 61959-1, ED.1. Mechanical tests for sealed portable alkaline secondary cells and batteries. Part 1. Secondary cells IEC DOCUMENT 21A/239/CD 01/202968 DC BS EN 60285. Ed.4. Secondary cells and batteries containing alkaline or other non-acid electrolytes. Sealed nickel-cadmium cylindrical rechargeable single cells BS 5932:1980 Specification for sealed nickel-cadmium cylindrical rechargeable single cells BS 6115:1981 Specification for sealed nickel-cadmium prismatic rechargeable single cells BS 6260:1982 Specification for open nickel-cadmium prismatic rechargeable single cells BS 3G 205:1983 Specification for lead-acid and nickel-cadmium rechargeable batteries

4.10.8. LEAD ACID BATTERY STANDARDS

IEC/TR3 61431:1995 Guide for use of monitor systems for lead-acid traction batteries IEC/TR 62060:2001 Monitoring of lead-acid stationary batteries User guide BS 3031:1996 Specification for sulphuric acid used in lead-acid batteries BS 4974:1975 Specification for water for lead-acid batteries BS 6133:1995 Code of practice for safe operation of lead-acid stationary batteries BS 6287:1982 Code of practice for safe operation of traction batteries BS 6290-2:1999 Lead-acid stationary cells and batteries. Specification for the high- performance Planté positive type

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BS 6290-3:1999 Lead-acid stationary cells and batteries. Specification for the flat positive plate type BS 6290-4:1997 Lead-acid stationary cells and batteries. Specification for classifying valve regulated types BS 7481:1992 Code of practice for testing venting systems and shields for lead-acid starter batteries BS 7483:1991 Specification for lead-acid batteries for the propulsion of light electric vehicles BS 6G 205-1:1995 Secondary batteries for aircraft. Specification for lead-acid batteries BS EN 50342:2001 Lead-acid starter batteries. General requirements, methods of test and numbering BS EN 60095-2:1993 Lead-acid starter batteries. Dimensions of batteries and dimensions and marking of terminals BS EN 60095-4:1993 Lead-acid starter batteries. Dimensions of batteries for heavy commercial vehicles BS EN 60254-1:1997, IEC 60254-1:1997 Lead-acid traction batteries. General requirements and methods of test BS EN 60254-2:1997 Lead-acid traction batteries. Dimensions of cells and terminals and marking of polarity on cells BS EN 60896-1:1992, IEC 60896-1:1987 Stationary lead-acid batteries. General requirements and methods of test. Vented types BS EN 60896-2:1996, IEC 60896-2:1995 Stationary lead-acid batteries. General requirements and methods of test. Valve regulated types BS EN 60896-11:2003 Stationary lead-acid batteries. General requirements and methods of test. Vented types. General requirements and methods of tests BS EN 61044:1993, IEC 61044:1990 Opportunity-charging of lead-acid traction batteries BS EN 61056-1:1993, IEC 61056-1:1991 Portable lead-acid cells and batteries (valve- regulated types). General requirements, functional characteristics. Methods of test BS EN 61056-1:2003 Portable lead-acid cells and batteries (valve-regulated types). General requirements, functional characteristics. Methods of test BS EN 61056-2:1997, IEC 61056-2:1994 Portable lead-acid cells and batteries (valve- regulated types). Dimensions, terminals and markings

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BS EN 61056-2:2003 Portable lead-acid cells and batteries (valve-regulated types). Dimensions, terminals and marking BS EN 61429:1997, IEC 61429:1995 Marking of secondary cells and batteries with the international recycling symbol ISO 7000-1135 88/74677 DC Aerospace series. Lead acid batteries for aircraft. General standard (prEN 3199) 99/200338 DC Aircraft batteries. Part 1. General test requirements and performance levels (IEC document 21/466/CD) 00/201034 DC BS EN 60896-1 Ed.2. Stationary lead-acid batteries. General requirements and methods of test. Part 1. Vented types (IEC Document 21/487/CD) 00/202302 DC BS EN 60952-2, Ed.2. Aircraft batteries. Part 2. Design and construction requirements (IEC Document 21/509/CD) 00/202303 DC BS EN 60952-3, Ed. 2. Aircraft batteries. Part 3. External electrical connectors (IEC Document 21/510/CD) 03/107988 DC IEC 60254-1. Lead-acid traction batteries. Part 1. General requirements and methods of tests BS 440:1964 Specification for stationary batteries (lead-acid Planté positive type) for general electrical purposes BS 2550:1971 Specification for lead-acid traction batteries for battery electric vehicles and trucks BS 2550:1983 Specification for lead-acid traction batteries BS 3031:1972 Specification for sulphuric acid for use in lead-acid batteries BS 3911:Part 1:1982 Lead-acid starter batteries for internal combustion engines. Specification for batteries requiring regular maintenance BS 3911:Part 2:1987 Lead-acid starter batteries for internal combustion engines. Specification for maintenance-free and low-maintenance batteries BS 4945:1973 Specification for miners' cap lamp assemblies (incorporating lead-acid type batteries) BS 6133:1982 Code of practice for safe operation of lead-acid stationary cells and batteries BS 6133:1985 Code of practice for safe operation of lead-acid stationary cells and batteries BS 6290:Part 1:1983 Lead-acid stationary cells and batteries. Specification for general requirements

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BS 6290-2:1984 Lead-acid stationary cells and batteries. Specification for lead-acid high performance Planté´ positive type BS 6290-3:1986 Lead-acid stationary cells and batteries. Specification for lead-acid pasted positive plate type BS 6290:Part 4:1987 Lead-acid stationary cells and batteries. Specification for lead- acid valve regulated sealed type BS 6745:Part 1:1986 Portable lead-acid cells and batteries. Specification for performance, design and construction of valve regulated sealed type BS AU 118:1965 Recommendations for the storage, shipment and maintenance of lead acid batteries for motor vehicles BS 3G 205:1983 Specification for lead-acid and nickel-cadmium rechargeable batteries BS 4G 205:Part 1:1987 Secondary batteries for aircraft. Specification for lead-acid batteries BS 5G 205:Part 1:1990 Secondary batteries for aircraft. Specification for lead-acid batteries BS EN 60095-1:1993 Lead-acid starter batteries. General requirements and methods of test

4.10.9. PHOTOVOLTAIC BATTERY STANDARDS

IEC 61427:1999 Secondary cells for solar photovoltaic energy systems General requirements and test methods 99/240906 DC BS EN 50314-1. Photovoltaic systems. Charge regulators. Part 1. Safety. Test requirements and procedures 99/240907 DC BS EN 50314-2. Photovoltaic systems. Charge regulators. Part 2. EMC. Test requirements and procedures 99/240908 DC BS EN 50314-3. Photovoltaic systems. Charge regulators. Part 3. Performance. Test requirements and procedures 99/240909 DC BS EN 50315-1. Accumulators for use in photovoltaic systems. Part 1. Safety. Test requirements and procedures 99/240910 DC BS EN 50315-2. Accumulators for use in photovoltaic systems. Part 1. Performance. Test requirements and procedures

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4.10.10. SAFETY STANDARDS

IEC 61508 The IEC requirements for the functional safety of Electrical/Electronic/Programmable Electronic Safety Related Systems BS EN 1175-1:1998 Safety of industrial trucks. Electrical requirements. General requirements for battery powered trucks BS EN 45510-2-3:2000 Guide for the procurement of power station equipment. Electrical equipment. Stationary batteries and chargers BS EN 50272-2:2001 Safety requirements for secondary batteries and battery installations. Stationary batteries BS EN60950-1: 2002 Low Voltage Directive (Safety) IEC/TR2 61430:1997 Test methods for determining the performance of devices designed for reducing explosion hazards - Lead-acid batteries IEC62133:2002 Secondary batteries containing alkaline or other non-acid electrolytes - Safety requirements for portable sealed secondary cells, and for batteries made of them, for use in portable applications IEC/TR2 61438:1996 Possible safety and health hazards in the use of alkaline secondary cells and batteries - Guide to equipment manufacturers and users ANSI C18.2M Safety Requirements for Portable Rechargeable Cells and Batteries UL 2054 Safety Requirements for Household and Commercial Batteries EN 45011 General requirements for bodies operating product certification schemes EAS The UK Electrotechnical Assessment Scheme (Electrical installation safety standards managed by the IEE) BS 2754 Memorandum. Construction of electrical equipment for protection against electric shock STRD Low Voltage Directive The Electrical Equipment (Safety) Regulations 1994 SI 1994 No. 3260 Implementing Directive 73/23/EEC (The Low Voltage Directive - LVD) IEC 479-1 Effects of current on human beings and livestock IEEE 80 2000 IEEE Guide for Safety in AC Substation Grounding HSG 85 HSE publication. Electricity at Work. Safe Working Practices NFPA 70E-1995 Standard for Electrical Safety Requirements for Employee Workplaces OSHA - 29 CFR 1910, Subpart S, Electrical industry safe occupational working standards

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ATEX Directive 94/9EC EN70079 Guidelines for equipment intended for use in potentially Explosive Atmospheres (ATEX)

4.10.11. AUTOMOTIVE BATTERY STANDARDS

QS 9000 The ISO 9000 derivative for suppliers to the automotive industry. Developed in the USA by Ford, General Motors and Daimler Chrysler ISO/TS16949:2002 Updated Technical Specification aligning US and European automotive quality supply chain standards IEC 61982-1 Test parameters IEC 61982-2:2002 Dynamic discharge performance test and dynamic endurance test IEC 61982-3:2001 Performance and life testing (traffic compatible, urban use vehicles) ISO11898 Specification for the CAN Bus ISO 9141(4) Specification for the LIN Bus SAE J240 Life Test for Automotive Storage Batteries SAE J537 Storage Batteries SAE J551 Performance levels and methods of measurement of electromagnetic radiation from vehicles and devices (30 to 1000 MHz) SAE J1127 Battery Cable SAE J1455 Recommended Environmental Practice for Heavy-Duty Trucks SAE J1718 Measurement of Hydrogen Gas Emission From Battery-Powered Passenger Cars and Light Trucks During Battery Charging SAE J1742 Connections for High Voltage On-Board Road Vehicle Electrical Wiring Harnesses-Test Methods and General Performance Requirements SAE J1766 Recommended Practice for Electric and Hybrid Electric Vehicle Battery Systems Crash Integrity Testing (Work in progress) SAE J1772 SAE Electric Vehicle Conductive Charge Coupler SAE J1773 SAE Electric Vehicle Inductively Coupled Charging SAE J1797 Recommended Practice for Packaging of Electric Vehicle Battery Modules SAE J1798 Recommended Practice for Performance Rating of Electric Vehicle Battery Modules SAE J1811 Power Cable Terminals SAE J1939 The SAE specification for the CAN Bus SAE J2185 Life Test for Heavy-Duty Storage Batteries

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SAE J2288 Life Cycle Testing of Electric Vehicle Battery Modules SAE J2289 Electric Drive Battery Pack System Functional Guidelines SAE J2293 Energy Transfer System for Electric Vehicles SAE J2344 Guidelines for Electric Vehicle Safety SAE J2380 Vibration Testing of Electric Vehicle Batteries SAE J2464 Electric Vehicle Battery Abuse Testing SAE J2602 The SAE specification for the LIN Bus PowerNet 42V Automotive industry consortium standard for 42 Volt batteries BCI Battery Technical Manual Automotive Lead Acid battery test procedures BCI Battery Service Manual General information about manufacturing and using automotive batteries. BCI Test Specifications Small Deep Cycling Batteries, Deep Cycle Marine/RV Batteries, Batteries for Golf Cars, Floor Maintenance Machinery ECE 100 Construction and functional safety requirements for battery electric vehicles ECE-15 UN/EEC driving load profile (See Battery Load Testing) EUDC UN/EEC Extra Urban Driving Cycle NEDC New European Driving Cycle (Modified cold start - No warm up) Also called the MVEG-B test FUDS Federal Urban Driving Schedule (USABC Load profile) SAE J227a/C and D SAE Driving Schedules DST Dynamic Stress Test (USABC battery test schedule) 2004/104/EC European EMC Automotive Regulation

4.10.12. STANDARDS FOR DIFFERENT UPS TOPOLOGIES AND METHODS OF PERFORMANCE MEASUREMENT

NFPA 111 1989 Standard for Stored Electrical Energy Emergency and Standby Power Systems

4.10.13. SOFTWARE STANDARDS

ISO/IEC 12207 Standard for software life cycle processes MISRA C 1998 Guidelines for the use of the C language in vehicle based software. Derived from IEC 61508 Functional Safety Standards

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4.10.14. INGRESS PROTECTION (IP) STANDARDS

ANSI/IEC 60529-2004 Degrees of Protection Provided by Enclosures (IP Code)

4.10.15. BATTERY MONITORING STANDARDS

IEC/TR 61431 1995 Guide for the use of monitor systems for lead-acid traction batteries IEC/TR 62060 2001 Secondary cells and batteries - Monitoring of lead acid stationary batteries - User guide

4.10.16. BATTERY RECYCLING AND DISPOSAL STANDARDS

EEC Directive 91/157 Batteries and accumulators containing certain dangerous substances. (Currently being revised) BS EN 61429:1997, IEC 61429:1995 Marking of secondary cells and batteries with the international recycling symbol ISO 7000-1135

4.10.17. OTHER RELATED ELECTRICAL STANDARDS

BS 7671:2001 The IEE Wiring Regulations (UK) NFPA 70 1993 National Electrical Code (USA) UL 1310 Safety of Class 2 Power Supplies, AC Adapters and Battery Chargers - Testing ISO 7176-4 1997 ANSI/RESNA WC04 Wheelchairs -- Part 4: Energy consumption of electric wheelchairs and scooters for determination of theoretical distance range BS EN 60598-2-22:1999 Luminaires. Particular requirements. Luminaires for emergency lighting

4.10.18. QUALITY STANDARDS

ISO 9000:2000 Quality management systems. Fundamentals and vocabulary

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ISO 14001:1996 Environmental management systems. Specification with guidance for use ISO 2859-0:1995 Sampling procedures for inspection by attributes ANSI/ASQC Z1.4 Sampling Procedures and Tables for Inspection by Attributes

4.11. Charging batteries

Charging a battery involves two different phases: the main charge phase and the final charge phase (Figure 17).

Figure 17. IU battery charging characteristic. Source: fn-electro.dk

The main charge phase takes part when the bulk of energy is recharged into the battery. A constant current it is used in this phase, and the time it gets depends on the available current and on the rating of the charger.

In the final charge phase it is used a constant voltage and usually takes several hours. It is necessary to make a periodical full charge of the battery for a good upkeep of batteries, because in mostly public stations just complete the main charge phase.

4.11.1. CHARGING INFRASTRUCTURE

The use of electric vehicles depends on the availability of efficient traction batteries. To transfer electricity to the distribution grid to the battery it is necessary a recharging infrastructure. The transfer can be done by conductive or inductive charging, been conductive charging the most widely used. There are different architecture concepts in order to assure empowering electric vehicles (Chart 8). Page 54 of 188

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Distributed concept Centralized concept Low power charging Fast charging station Battery swapping

Chart 8. EV architecture concepts

In order to take into account different situations to assure energy in short and long trips, it would be interesting to have a scenario were both concepts work together. That is to say a large number of low voltage charging points and a few fast charging stations and/or battery swapping stations were available.

Low power charging points (230V) would be available at residential buildings, office parking, public parking, etc. Fast charging and battery station would enhance travelling needs when the total battery capacity is not enough to storage energy for the whole trip. Fast charging station would be similar to gas station, where batteries would be charged in few minutes using high power charging. Battery swapping station would have batteries in store ready to be replaced in the vehicle, while empty batteries would be charging.

Anyway it is necessary to have a uniformed grid connection and communication interfaced based on open standards, to achieve global technology roll-out and durable infrastructure development, without market fragmentation due to incompatible charging systems. In order to have representation of automotive industry and power grid utilities it has been created and alliance between ISO (International Standards Organization) and IEC (International Electrotechnical Commission) with support of EURELECTRIC (Electricity Industry Union). Some important standards are shown in Chart 9.

Reference Title IEC TC69 (61851-1) Electrical vehicle conducting charging system IEC SC23H/PT62196 Dimensional interchangeability requirements for pin and contact-tube vehicle couplers ISO TC22/SC3/SC21 Road Vehicles IEC/ISO JWG V2G CI Joint Working Group for Vehicle to Grid communication Interface IEC TC57 (61850-7-420) Basic Communication structure for Distributed Energy

Chart 9. EV International standardization

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4.11.2. CHARGING POWER LEVELS

It has been established three different charging power levels: normal charging, semi- fast charging and fast charging. The power levels are going to have different values depending if it is been referring to Europe or to America. Depending on the geographical situation the electrical distribution is different and so the normal charging power available in domestic environment will be different.

First of all, it is going to be shown the characteristics of the European and the American distribution:

a) European electricity distribution

Based on historical developments and cultural tradition it is possible to find different characteristics. The first one it is the universal three phase distribution: four-wire three- phase distribution (3 x 400V + N) with 400 V between phases and 230 V between phase to neutral. The second one, it is three-wire three-phase distribution (3 x 230V), 230 V between phases.

b) American electricity distribution

American standard domestic outlets distribution is made of three-wire split phase system I which there is a tension of 120V between phase and neutral in standard. High-power consumers have 240 V between phases and rarely are found in domestic environment.

The characteristics of the different charging power levels established are list below:

I. Normal charging: a. Standard socket outlet b. Standard power outlet: i. 120V; 15 A; 1.8 kW (PF=1); “charge speed” 8km/h ii. 230V; 16 A; 3,7 kW; “charge speed” 16 km/h c. Universally available II. Semi fast charging: a. Higher power available in domestic environment Page 56 of 188

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b. Heavy single phase outlet i. 230V; 32 A; 7,4 kW, “charge speed” 32 km/h ii. Generally available in domestic environment (32 A: electric range) c. Three-phased outlet i. 3x400V; 16 A; 11 kW ii. Readily available in some countries III. Fast charging dc: a. High power connections b. Mode 4 charging c. Heavy expensive infrastructure d. Power typically 36 kW e. 80% charge in hour IV. Fast charging ac: a. High power connections b. Charging through traction inverter c. Connection to three phase mains d. No expensive stationary charger needed e. Opportunities for bidirectional power

4.11.3. CHARGING MODES FOR CONDUCTIVE CHARGING

It has been developed standard foresees four modes for charging electric vehicles. It is compiled in: IEC 61851-1. The 4 modes are listed below:

1) Mode 1 (AC): slow charging from a standard household-type socket-outlet. The electric vehicle is directly connected to a standard socket-outlet. The European socket-outlet provides up to 16A at 23V, which corresponds with normal power level. In America that corresponds with 15A at 120V what it is a low level to charge an automobile-sized vehicle. 2) Mode 2 (AC) – slow charging from a standard household-type socket-outlet with an in-cable protection device. It allows additional protection of the cable and the vehicle. Rarely used in Europe but used in America.

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3) Mode 3 (AC) – slow or fast charging using a specific EV socket-outlet and plug with control and protection function permanently installed. It is necessary to develop a control pilot device which controls the integrity of the protective conductor, gives additional safety functions and basic communication functions. Interesting mode for been used in charging stations located in public locations. Mode stations come in the three different power levels (normal, semi-fast and fast) 4) Mode 4 (DC) – fast charging using an external charger. It is a solution for fast charging stations which requires a heavy infrastructure.

The industrial socket-outlet, IEC SC 23H, published IEC 62196-1, which covers general requirements for EV connectors. It is going to be finalized closely IEC 62196-2 which standardizes elements for AC charging:

1) Type 1 – single phase vehicle coupler (vehicle connector and inlet), for example Yazaki or SAE J1772 (Japan, North America) 2) Type 2 – single and three phase vehicle coupler and mains plug and socket- outlet without shutters, for example VDE-AR-E 2623-2-2 3) Type 3 – single and three phase vehicle coupler and mains plug and socket- outlet with shutters, for example SCAME plug developed by the EV Plug Alliance

Also is developing IEC 62196-3, requirements for the vehicle DC coupler:

The work is still at an early stage and several proposals are on the table, including the DC quick charging CHAdeMO coupler as well as the possibility to use the same vehicle inlet both for DC and AC charging.

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4.11.4. RECENTLY APPROVED EUROPEAN STANDARD (2012)

Figure 18. European-approved connector

Finally, auto makers will beat mobile phone makers in launching a universal charger that is compatible with most devices. They say charging an electric vehicle using this system will take as little as 15 to 20 minutes. Currently, fast chargers need 30 minutes to 1 hour, and if you use the normal charger, it’s a 6-hour job.

Combined Charging System is the result of collaborative efforts between Audi, BMW, Chrysler, Daimler, Ford, General Motors, Porsche and Volkswagen. The system will get its first live demo at Electric Vehicle Symposium 26 (EVS26) May 6-9 2012. As a concept it works, but not sure if it is actually production-ready.

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Figure 19. Main characteristics of the connector

CCS integrates one-phase AC-charging, fast three-phase AC-charging, DC-charging at home and ultra-fast DC-charging at public stations into one vehicle inlet. In other words, it gives you options.

The system maximises capability for integration with future smart grid developments through common broadband communication methods regardless of the global location of the charging system. The combined charging approach will reduce development and infrastructure complexity, improve charging reliability, reduce the total cost-of- ownership for end customers and provide low maintenance costs.

The system has been chosen by SAE (Society of Automotive Engineers) as the standard for electric vehicle’s fast charging methods. ACEA, the European association of vehicle manufacturers has also selected the Combined Charging System as its AC/DC-charging interface for all new vehicle types in Europe beginning in 2017.

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The combo connector is an adaptation of an existing J1772 connector that has roots in the 1990’s. According to SAE, in 2010 the original J1772 standard was updated to a five-pin connector, to accommodate charging at 120 and 240 volts.

The latest J1772 charging port has two parts. The upper section retains the configuration of the 2010 standard, which means that slow-charging EVs already on the market can transition seamlessly to the new connector.

The lower section contains a second set of pins to accommodate fast-charging battery technology that was not commercially available in 2010. All together the combo connector will enable charging up to 500 volts.

Final approval for the new standard is expected by August 2012, and SAE expects the eight U.S. and German car makers to begin production of vehicles equipped with the new J1772 in 2013.

The global picture for standardization is still complicated by Japan, which has its own fast charging system called CHAdeMO.

So far the J1772 standard hasn’t stopped Japan from positioning itself to lead in the U.S. EV market, since car makers such as Nissan and Mitsubishi offer models with ports for both CHAdeMO and J1772 charging.

4.11.5. INDUCTIVE CHARGING

It is possible to transfer energy to the batteries using electromagnetic way. The energy transfer may be performed after juxtaposition two parts. It can be through a paddle or even without using any cable with an appropriate design and location of the inductors. So it is possible to charge batteries parking the vehicle adjacent to the primary conductor.

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Figure 20. Inductive recharge system investigated by Volvo.

4.12. Design guidelines related to energy storage devices

4.12.1. SPECIFICATIONS ACCORDING TO STANDARDS

Quadricycles (L7e), also referred to as Heavy Quadricycles, are defined by Framework Directive 2002/24/EC as motor vehicles with four wheels "other than those referred to (as light quadricycles), whose unladen mass is not more than 400 kg (category L7e) (550 kg for vehicles intended for carrying goods), not including the mass of batteries in the case of electric vehicles, and whose maximum net engine power does not exceed 15 kW.

These vehicles shall be considered to be motor tricycles and shall fulfil the technical requirements applicable to motor tricycles of category L5e unless specified differently in any of the separate Directives".

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4.12.2. WEIGHT OF THE BATTERY PACK ACCORDING TO VEHICLE CATEGORY

As the total allowed power is only 15 kW, the total vehicle weight (400 Kg or 550 without batteries) should be kept as small as possible to increase vehicle performance, and in consequence, the weight of the battery pack must be optimized.

4.12.3. THE GENERAL REQUIREMENTS FOR TRACTION BATTERIES

The general requirements are, as for all battery applications: low cost, long life (more than 1000 cycles), low self-discharge rates (less than 5% per month) and low maintenance are basic requirements for all applications. But traction batteries have added requirements: generally operate in very harsh operating environments and must withstand wide temperature ranges (-30°C to +65°C) as well as shock, vibration and abuse. Also, low weight is however essential for high capacity automotive EV and HEV batteries used in passenger vehicles. Protection circuits are also essential for batteries using non-lead acid chemistries.

4.12.4. BATTERY CHARGING

Use of the recently approved European Charging connector (please, refer to section 4.11.4

4.12.5. BATTERY TECHNICAL FEATURES FOR BEVS

The following diagram shows in a graphic way the expected requirements for the battery pack.

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High energy density

HEV Fast charging High power

PHEV

Cycle life Safety BEV

Cost

Figure 21. According to the different vehicle technology

4.12.6. BATTERY PLACEMENT

Battery placement is therefore critical. The battery pack is heavy and voluminous. In passenger cars typical, if only possible, solutions are:

1. Under the bonnet/hood 2. In the tunnel 3. In the trunk/luggage compartment

Notice that the assumption is made that all the battery assembly is kept in a single pack. This is to avoid further electric complication.

Battery placement influences:

• Dynamics: placement of the masses • Crash: especially side and rear crash tests • Production: mass production can impose a determine architecture • Economics: in the case of hybrid or vehicles derived from ICE, use the same platform

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4.12.7. POSITIONING IN THE VEHICLE

Tunnel

The battery pack is set in the tunnel, where usually is place for the transmission shaft to the rear differential in a rear-wheel traction or 4WD system. Placing the battery in the tunnel offers the following advantages:

• Dynamics: masses are distributed along the centre axis of the vehicle and in the lowest position • Crash: batteries are in a “safe” place with respect to side crash • Production: batteries are assembled with the drivetrain, no need to package batteries at the end of the assembly process • Economics: there are just a few changes on the chassis

Safety issues have been addressed by various manufacturers. Volvo C50 electric car has been tested and the safety level of this solution has been demonstrated.

Batteries in the trunk: above the rear axle

The battery pack is set above the rear axle, behind the second row of seats. In the case of a freight transport vehicle it would be behind the cabin.

Placing the battery in the trunk offers the following advantages:

• Dimensions: there are few limitations on the size of the battery pack and its shape; several configurations of the battery pack can be adopted • Crash: batteries are placed in a secure place with respect to side crash • Economics: limited changes in the chassis; the pack is installed at the end of the assembly line in the trunk

Drawbacks are the following:

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• Dynamics: suspensions must be reinforced since a higher mass is standing on the rear axle; moreover, the dynamic behaviour of the vehicle will be affected by a different disposition of the masses • Production: batteries are separated from the drivetrain; therefore, the are installed at the end of the assembly line in the trunk, requiring special areas in the plant for such installation and dedicated work-force

Again there are examples from Volvo demonstrating that the battery pack can be securely protected avoiding serious perils.

4.12.8. STANDARDS AND REGULATIONS REGARDING SAFETY

The safety issues of battery electric vehicles are largely dealt with by the international standard ISO 6469. This document is divided in three parts dealing with specific issues:

 On-board electrical energy storage, i.e. the battery  Functional safety means and protection against failures  Protection of persons against electrical hazards

See an extensive standard collection in section 4.10.

4.13. References

[1] The society of Motor Manufacturers and Traders (SMMT): Electric Car Guide 2010 [2] The society of Motor Manufacturers and Traders SMMT): Electric Car Guide 2011 [3] http://en.wikipedia.org/wiki/Tata_Indica#Tata_Indica_Vista_Specifications [4] http://en.wikipedia.org/wiki/Chevrolet_Volt [5] http://en.wikipedia.org/wiki/Lightning_GT [6] http://en.wikipedia.org/wiki/Tesla_Model_S [7] Electric and Hybrid Vehicles. Peter Van den Bossche, 2010 [8] http://www.iec.ch/ [9] International Energy Agency “Technology Roadmap: Electric and plug-in hybrid electric vehicles” [10] http://www.chademo.com/ [11] http://haloipt.com [12] Report on the Joint EC/EPoSS/ERTRAC Expert Workshop 2009 “Batteries and Storage Systems for the Fully Electric Vehicle”. Version 7 / 25 September 2009 Page 66 of 188

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[13] http://www.batteryfacts.co.uk/ [14] http://en.wikipedia.org/wiki/VRLA_battery [15] Report on the Joint EC/EPoSS/ERTRAC Expert Workshop 2009. Batteries and Storage Systems for the Fully Electric Vehicle. Version 7 / 25 September 2009 [16] Tesla Motors – 2007 “The Tesla Roadster Battery System.” Gene Berdichevsky, Kurt Kelty, JB Straubel y Erik Toore. [17] Modern Electric, Hybrid Electric, and Fuel Cell Vehicles. Fundamentals, Theory and Design. Ehsani, Gao, Gay, Ali. CRC Press. 2005. [18] VOLVO PUBLICITY CAMPAIGN: Detroit Auto Show 2011: Crash-tested C30 Electric on display – youtube videos. [19] Ernst-Mach Institut EMI, Fraunhofer Institutes for Mechanics of Materials IWM, for Structural Durability and System Reliability LBF and for High-Speed Dynamics. [20] http://www.nhtsa.gov/PR/Volt [21] The 21st Century Electric Car. Martin Eberhard and Marc Tarpenning. Tesla Motors Inc. 6 October 2006. [22] Dow Kokam Xalt™ Cell Technology: http://www.dowkokam.com/cell- specifications.php [23] Amberjack-Projects http://www.amberjac-projects.co.uk/ [24] Axeon http://www.axeon.com/Default.aspx

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5. Powertrain architecture for ELTVs. Analysis of vehicle performance and vehicle vertical dynamics

5.1. Introduction

Modern trends of EVs architectures contemplate the use of in-wheel motors instead of the classical single traction motor. An example of this solution is given in Figure 22 and Figure 23.

Figure 22. Protean in-wheel motors.

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Figure 23. Mercedes Brabus architecture.

There are important differences in the performance curves of classic ICEs and electric traction motors, these being mainly PMSMs (permanent magnet synchronous motors):

Figure 24. Characteristic curves of an internal combustion engine and an electric motor

The lack of gearbox in EVs with in-wheel motors (direct drive) introduces also important differences between both vehicle configurations in the tractive effort / resistance-grade curves.

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Figure 25. Tractive effort / resistance on grade curves of an ICE vehicle.

Figure 26. Tractive effort / resistance on grade curves of a typical PMSM (direct drive).

The use of in-wheel motors brings some advantages and disadvantages:

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Advantages

 General simplicity of the powertrain and drive line.  Availability of free space at the vehicle front.  Less energy loses during power transmission to the wheels.  Possibility to control the operation of each motor/wheel separately, to implement new active safety capabilities.

Disadvantages

 Lower vehicle performance at low speed, as there isn’t any variable gear box in the driveline. Most electric motors give their maximum output torque from a very low rotational speed. This is not the case of typical ICEs. However, when used in in-wheel motors for traction, electric motors are directly connected to the wheel (direct drive), without any reduction gear able to multiply the applied torque. On the contrary, typical ICE drivelines have gearboxes between the engine and the wheel. These gearboxes multiply the low output torque provided by the engine, applying in consequence a greater torque to the wheel, resulting in greater acceleration.  Increment of the unsprung weight, with the corresponding deterioration of the tire vertical behaviour.  Less robustness and reliability, as this technology is new.

In the following sections, the first two disadvantages indicated are analysed, in order to quantify its importance and impact in the general vehicle concept.

5.2. ICE vehicle performance vs. EV (direct drive) performance

This section presents a performance comparative analysis of two vehicles, Volvo C30 and Opel Vivaro (Figure 27 and Figure 31), each equipped either with an internal combustion engine or with in-wheel motors, keeping in both cases the same

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nominal power and mass (this is not totally realistic, but it facilitates the performance comparison).

The objective of this study is to compare the vehicle acceleration capacity at different speed levels.

5.2.1. SIMULATION PERFORMANCE OF VOLVO C30 DIESEL OR ELECTRIC

Figure 27. Picture of Volvo C30 D4 Kinetic

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DATA VOLVO C30 DIESEL VOLVO C30 ELECTRIC

SPECIFICATIONS DIESEL ELECTRIC

Motor 2.0 D Protean Electric PD 18 (2x) Maximum power 130 kW – 177 HP 128 kW – 174 HP Maximum torque 400 Nm 1000 Nm Transmission Gearbox, manual, 6 gears Direct drive 1:1 i differential 3.758 - i1 3.385 - i2 1.905 - i3 1.194 - i4 0.838 - i5 0.652 - i6 0.54 - Mechanical efficiency 0.93 0.99 Starting time 0.8 s - Gear changing time 0.5 s - Mass 1524 kg Frontal Area 2.18 m2 Drag Coefficient Cx 0,31 Rolling Coefficient 0,015 Tires 205/55 R16 Tire circumference 1.9223 m

Chart 10. Technical features of Volvo C30 D4 Kinetic diesel or electric.

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P (HP)

P (HP)

Figure 28. ICE output curves (power and torque) of Volvo C30 D4 Kinetic diesel. P (HP)

P (HP)

Figure 29. Motor output curves (power and torque) of Volvo C30 D4 Kinetic electric.

The performance of both vehicles, each one equipped either with Ian CE or an electric motor, were simulated and calculated..

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Volvo C30 analysis (s) accelerate to Time

Figure 30. Acceleration time for Volvo C30 diesel or electric

5.2.2. SIMULATION PERFORMANCE OF OPEL VIVARO DIESEL OR ELECTRIC

This section presents a study similar to the one developed in section 5.2.1. The interest of this section comes from the fact that the type of vehicle used in the simulations is a van, which is a type of vehicle closer to the target vehicle of OPTOBODY project.

Figure 31. Opel Vivaro van, 2.5 CDTI L1H1

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DATA OPEL VIVARO DIESEL OPEL VIVARO ELECTRIC

SPECIFICATIONS DIESEL ELECTRIC

Motor 2.5 CDTi Protean Electric PD 18 (2x) Maximum power 107 kW – 146 HP 107 kW – 146 HP Maximum torque 320 Nm 840 Nm Transmission Gearbox, manual, 6 gears Direct drive 1:1 i differential 4.19 - i1 3.91 - i2 2.11 - i3 1.39 - i4 0.98 - i5 0.76 - i6 0.6 - Mechanical efficiency 0.93 0.99 Starting time 0.7 s - Gear changing time 0.8 s - Mass 2096 kg Frontal Area 3.36 m2 Drag Coefficient Cx 0,362 Rolling Coefficient 0,015 Tires 215/65 R16 Tire circumference 2.092m

Chart 11. Technical features of Opel Vivaro diesel or electric.

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P (HP)

P (HP)

Figure 32. ICE output curves (power and torque) of Opel Vivaro 2.5 CDTI L1H1. P (HP)

P (HP)

Figure 33. Electric motor output curves (power and torque) of Opel Vivaro

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Figure 34. Acceleration time for Opel Vivaro diesel or electric

5.3. L7e electric vehicle performance in continuous / peak operation.

As explained in section 2.2.1, OPTIBODY project focuses basically on L7e vehicles.

This section analyses the performance of an average L7e vehicle equipped in in-wheel motors in nominal and peak conditions. Peak means extreme use conditions, kept for only few seconds.

Traction motors have nominal and peak output curves. Peak performance can eventually be as two times bigger as continuous performance. In consequence, the vehicle performance is completely different. To illustrate this fact, a simulation case is presented. Chart 12 details the technical specifications of two vehicles, each using one model of commercial in-wheel motor.

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SPECIFICATIONS

Vehicle class L7e Reference vehicles Mega Pick-Up / BEEPO PONY PICK UP Overall weight 650 kg Frontal area 2,313 m2 Cx coefficient 0,45 Rolling resistance coeff. 0,011 Tires 165/70 R13 Effective radius 0,2806 m EV CONFIGURATION 1 EV CONFIGURATION 2

Motor PERM Motor PRA230 II (4x) NGM SCM150 (4x) Continuous max. power 2,2 kW 3,75 kW Continuous max. torque 130 Nm 57 Nm Peak max. power N/A 6,2 kW Peak max. torque N/A 105 Nm Weight 16 kg 20 kg Transmission Direct, ratio 1:1 Direct, ratio 1:1 Mechanical efficiency 0,98 0,98 Battery type Lithium-ion Lithium-ion Capacity 200 Ah 200 Ah Nominal Voltage 48 V 48 V Max. intensity 200 A 266 A Max. power 9,6 kW 12,8 kW Energy stored 9,6 kWh 9,6 kWh Aprox. weight 72-100 kg 72-100 kg

Chart 12. Vehicle specifications.

5.3.1. PERFORMANCE COMPARISON

Once the vehicles are described and defined in the previous sections, Chart 13 contains the main results obtained from the performance simulation.

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PERFORMANCE EV 1 EV 2

Nominal Continuous Peak

Powertrain specs.

Max. Torque 520 Nm 228 Nm 432 Nm

Max. Power 8,8 kW 15 kW 24,8 kW

Acceleration

0-30 km/h 4,053 sec 8,05 sec 4,01 sec

0-50 km/h 9,905 sec 14,3 sec 6,85 sec

0-1000 m 56,38 sec 54,15 sec 42,24 sec

0- Max. Speed 65,14 sec 79,61 sec 46,45 sec

Max. Speed 79,34 km/h 95,5 km/h 110 km/h

Consumption

ECE_R15 cycle 6,011 kWh/100 km 6,595 kWh/100km (EU) City II cycle (EEUU) * 7,051 kWh/100km 11_MODE_4 * 7,899 kWh/100km cycle(JP) Driving range

ECE_R15 (EU) 159 km 145 km

City II (EEUU) * 136 km

11 MODE_4 (JP) * 121 km

* The power demand at some point of these cycles exceeds the maximum power which can be provided by this engine.

Chart 13. Summary of the vehicles’ performance simulation cases.

EV configuration I (PERM Motors)

This section develops a performance simulation of EV1. What is calculated is:

 vehicle speed vs. time (full throttle)  distance travelled vs. time (full throttle)

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 energy consumption following the ECE cycle (Figure 49)

The basic motor definition curves and diagrams are given in Figure 35 to Figure 37. Simulation results are given in Figure 38 to Figure 41, summarized in Chart 13.

Figure 35. Motor curves (4x PERM Motors)

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Figure 37. Efficiency (4 x PERM acting as generators)

Figure 38. Traction Force vs. Resistances

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Figure 39. Full power acceleration

Figure 40. Distance travelled at full power acceleration

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Figure 41. Battery data for ECE cycle (Initial SOC 80%)

EV configuration 2 (SGM Motors)

This section develops a performance simulation of EV2. What is calculated is:

 vehicle speed vs. time (full throttle)  distance travelled vs. time (full throttle)  energy consumption following the ECE cycle (Figure 49)

The basic motor definition curves and diagrams are given in Figure 42 to Figure 44 Figure 37. Simulation results are given in Figure 45 to Figure 48.

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Figure 42. Engine curves (4x SGM Motors)

Figure 43. Efficiency (4x SGM Motors)

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Figure 44. Efficiency (4x SGM acting as generators)

Figure 45. Traction force vs. Resistances

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Figure 46. Full power acceleration

Figure 47. Distance travelled at full power acceleration

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Figure 48. Battery data for ECE cycle (Initial SOC 80%)

Driving cycles

The driving cycles used in the simulation are detailed in Figure 49 to Figure 51.

Figure 49. ECE Cycle

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Figure 50. City II Cycle

Figure 51. 11 MODE Cycle

5.4. Conclusions on vehicle performance

From the analysis of the results in the previous sections the following conclusions can be extracted:

 Having the same nominal power, vehicles equipped with a gear box in its powertrain are able to provide greater acceleration at low speed levels. At high speed levels, electric direct drive provides greater acceleration.

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curves much greater that nominal curves. This fact is relevant in manoeuvres such as overtaking, highway access, etc.

5.5. In-wheel motors and vehicle vertical dynamics

5.5.1. INTRODUCTION

The fact of introducing in-wheel motors instead of the classic motors acting on the axle differential obviously increases the wheel weight.

As, it is well known [10] from many vehicle vertical dynamics studies, the increment of the wheel weight (called unsprung mass) results in a worse tire-soil contact.

This section tries to quantify the impact of the wheel weight increment for OPTIBODYs ELTVs in the tire vertical dynamics.

5.5.2. VEHICLE VERTICAL DYNAMICS WITH IN-WHEEL MOTORS: QUARTER-CAR MODEL

The Quarter Car Model (QCM) or De Carbon model intends the analysis of just one- quarter of the total car (Figure 52). This model is particularly important in vehicle dynamics, as it enables the study of many factors in vehicle riding.

Figure 52. Main principle of the Quarter Car Model.

The model is formed by the following elements:

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X2

M2

K2 C2

X1 M1

K1 C1 X

Figure 53. Fig. III.2-11: The Quarter Car Model representation.

where:

 M1= unsprung mass (mass of tire + axle +tire supporting bars).

 M2= sprung mass (vehicle body mass).

 K1= tire vertical stiffness.

 C1= tire damping coefficient.

 K2= suspension stiffness.

 C2= suspension damping coefficient.

The dynamic equations governing this system are:

(Usually the tire damping effect is neglected, C1 << )

This system can be interpreted in the following way:

INPUTS

x(t) = road unevenness

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OUTPUTS

x1(t) = tire vertical motion

x2(t) = car body vertical motion

Associated Transfer Functions Of The 2-DOF Model

The transfer function is defined as the ratio of the Laplace transform of the output and the Laplace transform of the input. In case of multiple outputs, as it is the case of the QCM, each pair input-output defines a different transfer function:

Transfer function Ft2(s), which relates the motion of the sprung mass M2 - (X2) with the road unevenness (X):

2 C1C2 s + [K2 C1 + K1C2 ]s + K1 K2 Ft (s) = 2 4 3 2 2 2 m1m2 s + [m2 (C1 + C2 ) + m1C2 ]s + [m2 (K1 + K2 ) + C2 (C1 + C2 ) + m1 K2 − C2 s]s + [C2 (K1 + K2 ) + K2 (C1 + C2 ) − 2C2 K2 ]s + [K2 (K1 + K2 ) − K2 ]

Transfer function F1(s), which relates the motion of the unsprung mass M1 - (X1) with the road unevenness (X):

3 2 C1m2 s + [m2 K1 + C1C2 ]s + [K2 C1 + K1C2 ]s + K1 K2 Ft (s) = 1 4 3 2 2 2 m1m2 s + [m2 (C1 + C2 ) + m1C2 ]s + [m2 (K1 + K2 ) + C2 (C1 + C2 ) + m1 K2 − C2 s]s + [C2 (K1 + K2 ) + K2 (C1 + C2 ) − 2C2 K2 ]s + [K2 (K1 + K2 ) − K2 ]

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5.5.3. VERTICAL DYNAMICS SIMULATION CASE: OPEL VIVARO

To illustrate the effect of unsprung mass increment on the tire vertical dynamics, a simulation case is developed.

Chart 14 gives the main technical parameters of an Opel Vivaro, equipped either with a conventional powertrain (diesel) or with in-wheel motors.

Parameters Opel Vivaro diesel Opel Vivaro electric

m1 20 kg 46 kg m2 504 kg 478 kg k1 110000 N/m k2 44768 N/m c1 37,5 Ns/m c2 1031 Ns/m ω1 14 Hz 9,23 Hz ω2 1,5 Hz 1,54 Hz

Chart 14. Main technical parameters to perform a vertical dynamics simulation

These parameters are used to obtain the two Bode diagrams of FT1 and FT2 explained in section 5.5.3. Results are shown in Figure 54 and Figure 55.

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Figure 54. Bode diagram of FT1 (wheels)

Figure 55. Bode diagram of FT2 (body)

5.5.4. TIRE VERTICAL DYNAMICS COMPENSATION

Clearly, the tire dynamic behaviour given in Figure 54 shows a worst soil-tire contact for the case of in-wheel motors. The way to compensate this problem is the introduction of stronger dampers.

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Figure 56 shows the evolution of the wheel gain and resonance frequency as function

of C2 value. There is a clear positive evolution as C2 increases. At a value of approx. 1500 N.s/m, gain reaches 0 dB, which means that the tire behaves properly, without an excessive rebound tendency. Figure 57 shows that the body behaviour is not

significantly affected with the increment in C2 value.

4 -20 Gananciagain Frecuenciafrequency 2 -30

0 -40 [rad/s] ω -2 -50 ∆ desplacement [dB] desplacement ∆ -4 -60 900 1100 1300 1500 1700 1900 2100 2300 2500 C Opel Vivaro electric [Ns/m] 2

Figure 56. Evolution of wheel gain and frequency as C2 increases.

0 1 Gananciagain Frecuenciafrequency -2 0,6 -4 0,2

-6 -0,2 [rad/s] ω ∆

desplaceent [dB] desplaceent -8 -0,6 ∆ -10 -1 900 1100 1300 1500 1700 1900 2100 2300 2500

C2 Opel Vivaro electric [Ns/m]

Figure 57. Evolution of the vehicle body gain and frequency as C2 increases.

5.6. Conclusions

 The installation of in-wheel motors negatively affects the vertical dynamics of the vehicle, reflected in an increase of the tire vertical displacement, which leads to a loss of soil-tire contact. However, this increase in unsprung mass does not significantly affect the comfort of the passengers. Page 95 of 188

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 An increase of between 50-70% of the levels of damping corrects and restores the correct behaviour of wheels, without significantly affecting the comfort of the occupants.

5.7. Design guidelines derived from the contents in chapter 5.

5.7.1. REGARDING VEHICLE PERFORMANCE

 Vehicles equipped with a gear box in its powertrain are able to provide greater acceleration at low speed levels than vehicle with direct drive, as it is the case of the in-wheel motors. At high speed levels, electric direct drive provides greater acceleration. Depending on the performance sought or the specific EV application, this fact must be carefully considered.  The performance of electric vehicles can largely exceed nominal values in short periods of time, as electric traction motors present peak output curves much greater that nominal curves. This fact is relevant in manoeuvres such as overtaking, highway access, etc.

5.7.2. REGARDING VEHICLE VERTICAL DYNAMICS

 The installation of in-wheel motors implies an increment in the vehicle unsprung mass. This fact implies in turns, a worst tire vertical dynamic

behaviour. There is a clear positive evolution as the value of C2 increases. At a value of approx. 1500 N.s/m (approximately 80% bigger than its regular value), gain reaches 0 dB, which means that the tire behaves properly, without an excessive rebound tendency. It has been demonstrated that the body behaviour is not significantly affected with that

increment in C2 value.

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5.8. References

[1] Larminie, James y Lowry, John. Electric Vehicle Technology Explained. John Wiley & Sons, Ltd, 2003.

[2] Rix, Arnold. Design, Comparison and Experimental Evaluation of Non-Overlap Winding Radial Flux Permanent Magnet Hub Drives for Electric Vehicles. Stellenbosch, 2011.

[3] Ehsani, Mehrdad, Gao, Yimin y Emadi, Ali. Modern Electric, Hybrid Electric and Fuel Cell Vehicles: Fundamentals, Theory and Design. : CRC Press.

[4] Romero Perez, Sergio. Analysis of a Light Permanent Magnet In-wheel Motor for an Electric Vehicle with Autonomous Corner Modules. Stockholm, 2011.

[5] Vallance, Andrew. Advanced In-wheel Electric Propulsion Technology. [Presentación] : Protean Electric, April 2011.

[6] Protean, Electric. Protean Electric Company Site. [En línea] 2012. http://www.proteanelectric.com/.

[7] Baselga Ariño, Santiago & Maza Frechín, Mario. Principios Básicos para Cálculo de las Prestaciones del Automóvil. Zaragoza: CopyCenter, 2000. ISBN 84-931279-8-1.

[8] Guzzella, Lino y Sciarretta, Antonio. Vehicle Propulsion Systems. Zürich : Springer, 2005. ISBN 978-3-540-74691-1.

[9] Maza Frechín, Mario, Baselga Ariño, Santiago y Ortiz Sanchez-Lafuente, Jesús. Problemas de Diseño de Vehículos. 2004.

[10] Maza Frechín, Mario, Baselga Ariño, Santiago Simulación del Comportamiento Dinámico Vertical de Vehículos. 2001.

[10] Rodríguez Galbarro, Hermenegildo. Clasificación de Categorías y Tipos de Vehículos. : ARATEC Ingeniería.

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[11] Bovenkerk, J. y Fassbender, S. Strategies for Enhanced Pedestrian and Cyclist Friendly Design. : APROSYS SP2, 2006.

[12] Fassbender, S. y Gugler, J. Demonstrator module for new design concepts. : APROSYS SP2, 2008.

[13] Feist, F. y Fassbender, S. System Description of the Experimental Safety Module. : APROSYS SP2, 2008.

[14] Demonstration of Truck Front Design Improvements for Vulnerable Road Users. : APROSYS SP2, 2008.

[15] Transportation Research Board Special Report 286 “Tires and Passenger Vehicle Fuel Economy”

[16] “TOTAL AUTOMOTIVE TECHNOLOGY”. ANTHONY E. SCHWALLER. THOMSOM DELMAR LEARNING.

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6. Weight reduction: options for lighter vehicles and its impact on fuel saving

6.1. Introduction

Vehicle weight reduction is a well-known strategy for improving fuel consumption in vehicles, and presents an important opportunity to reduce fuel use in the transportation sector.

By reducing the mass of the vehicle, the inertial forces that the engine has to overcome are less, and the power required to move the vehicle is thus lowered. In this section, weight reduction as a strategy to reduce fuel consumption will be explored. In fact, from all technical parameters which could be optimised in the design of a vehicle (except the motor/engine efficiency), the mass is the parameter that most affects fuel consumption. To demonstrate this assertion, a study case is developed.

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Vehicle class L7e L7e_passengers N1 N2 Reference vehicles Mega Pick-Up / BEEPO PONY PICK UP TAZZARI ZERO Standard Mercedes-Benz ESPAÑA Vito Furgón MODEC

Vehicle data Motors PERM Motor PRA 230 (4x) PERM Motor PRA 230 (2x) Protean Electric PD 18 (2x) Protean Electric PD18 (2x) Continuous power kW 8,8 4,4 128 128 Continuous torque Nm 400 200 1000 1000 Peak power kW - - 162 162 Peak torque Nm 520 260 1600 1600

Mass Kg 650 500 2500 3000 Frontal area m2 2,313 1,9 3,1 5,3 Cx 0,45 0,4 0,34 0,4 Rolling resistance 0,011 0,011 0,011 0,011

Tyres 165/70 R13 165/70 R13 205/50 R17 205/75 R17.5 Radius m 0,2806 0,2806 0,3209 0,376

Batteries Charge capacity Ah 300 200 100 150 Voltage V 48 48 400 400 Energy stored kWh 15 9,6 40 60 Aprox. weight kg 100-125 75-100 265-300 400-500

Results Consumption kWh/100km 50 km/h 6,641 4,943 13,56 19,741 90 km/h - - 26,41 45,591 Cycle ECE_R15 7,404 5,766 18,7 24,797 Cycle NEDC - - 21,55 32,094 Driving range km 50 km/h 225,9 303,5 295,1 303,9 90 km/h - - 151,5 131,6 Cycle ECE_R15 202,6 166,5 213,91 241,9 Cycle NEDC - - 185,6 186,9

Max. speed 79 km/h 70 km/h 190 km/h 143 km/h RPM @ max.speed RPM 750 661 1571 1009 Chart 15. Technical data of some example vehicles. Page 100 of 188

Chart 15 contains the main technical data of a sample of vehicles, taken as example to illustrate the impact on fuel consumption introduced by the modification of those technical data.

Chart 16 shows the impact on fuel consumption, obtained from simulation, according to ECE_R15 cycle. It can be noticed (highlighted in green) that the most significant fuel consumption reduction is achieved by reducing the vehicle mass, while the less significant reduction is obtained with either frontal area or Cx reduction.

Data in Chart 17 show the same results, in this case considering the vehicles running at constant speed.

SENSITIVITY ANALYSIS WITH ECE_R15 CYCLE

L7e L7e passengers N1 N2 Original consumption 7,404 5,766 18,7 24,797 Original autonomy 202,6 166,5 213,91 241,9 MASS -10% Consumption (Kwh/100km) 6,879 -7,09 % 5,33 -7,56 % 17,044 -8,86 % 22,573 -20% 6,387 -13,74 % 4,91 -14,85 % 15,437 -17,45 % 20,431 -10% Autonomy (km) 218,1 7,63 % 180,1 8,18 % 234,7 9,71 % 265,8 -20% 234,9 15,92 % 195,5 17,43 % 259,1 21,13 % 293,7 FRONTAL AREA -10% Consumption (Kwh/100km) 7,146 -3,48 % 5,575 -3,31 % 18,495 -1,10 % 24,37 -20% 6,894 -6,89 % 5,387 -6,57 % 18,286 -2,21 % 23,941 -10% Autonomy (km) 209,9 3,61 % 172,2 3,43 % 216,3 1,11 % 246,2 -20% 217,6 7,40 % 178,2 7,04 % 218,7 2,26 % 250,6 Cx -10% Consumption (Kwh/100km) 7,146 -3,48 % 5,575 -3,31 % 18,495 -1,10 % 24,37 -20% 6,894 -6,89 % 5,387 -6,57 % 18,286 -2,21 % 23,941 -10% Autonomy (km) 209,9 3,61 % 172,2 3,43 % 216,3 1,11 % 246,2 -20% 217,6 7,40 % 178,2 7,04 % 218,7 2,26 % 250,6 μr -10% Consumption (Kwh/100km) 7,115 -3,90 % 5,541 -3,90 % 17,8 -4,81 % 23,68 -20% 6,836 -7,67 % 5,318 -7,77 % 16,902 -9,61 % 22,563 -10% Autonomy (km) 210,8 4,06 % 173,3 4,06 % 224,7 5,05 % 253,4 -20% 219,4 8,31 % 180,5 8,42 % 236,7 10,63 % 265,9 Chart 16. Technical parameters modification. Impact on fuel consumption according to ECE_R15 cycle. Page 101 of 188

Sensitivity analysis at constant speed 50 km/h

L7e L7e passengers N1 N2 Original consumption 6,641 4,943 13,56 19,741 Original autonomy 225,9 303,5 295,1 303,9 MASS -10% Consumption (Kwh/100km) 6,4 -3,63 % 4,748 -3,94 % 12,628 -6,87 % 18,629 -20% 6,159 -7,26 % 4,572 -7,51 % 11,7 -13,72 % 17,516 -10% Autonomy (km) 234,4 3,76 % 315,3 3,89 % 316,8 7,35 % 322,1 -20% 243,6 7,84 % 328,1 8,11 % 341,9 15,86 % 342,5 FRONTAL AREA -10% Consumption (Kwh/100km) 6,218 -6,37 % 4,634 -6,25 % 13,126 -3,20 % 18,88 -20% 5,795 -12,74 % 4,325 -12,50 % 12,698 -6,36 % 18,018 -10% Autonomy (km) 241,2 6,77 % 323,7 6,66 % 304,7 3,25 % 317,8 -20% 258,9 14,61 % 346,8 14,27 % 315 6,74 % 333,0 Cx -10% Consumption (Kwh/100km) 6,218 -6,37 % 4,634 -6,25 % 13,126 -3,20 % 18,88 -20% 5,795 -12,74 % 4,325 -12,50 % 12,698 -6,36 % 18,018 -10% Autonomy (km) 241,2 6,77 % 323,7 6,66 % 304,7 3,25 % 317,8 -20% 258,9 14,61 % 346,8 14,27 % 315 6,74 % 333,0 μr -10% Consumption (Kwh/100km) 6,4 -3,63 % 4,748 -3,94 % 12,628 -6,87 % 18,629 -20% 6,159 -7,26 % 4,572 -7,51 % 11,7 -13,72 % 17,516 -10% Autonomy (km) 234,4 3,76 % 315,3 3,89 % 316,8 7,35 % 322,1 -20% 243,6 7,84 % 328,1 8,11 % 341,9 15,86 % 342,5 Chart 17. Technical parameters modification. Impact on fuel consumption running at constant speed.

6.2. Historical vehicle weight trends, US study case

In the United States, the sales-weighted average new light-duty vehicle weight is 1,880 kg (4,144 lb) today, and has been increasing slowly but steadily at a rate of about 1% per year since the early 1980s (see Figure 60(a)). Since the mid-1980s, the popularity of larger and heavier light trucks, especially sport utility vehicles (SUVs), was partly responsible for the upward weight trend. The market share of SUVs has increased by more than a factor of 10, from less than 2% of the new light-duty vehicle market in 1975 to 27% of the market today. Conversely, the market share of new passenger cars and station wagons has decreased by more than 30% (Figure 58).

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Figure 58. Sales-weighted average new U.S. light-duty vehicle weight.

Figure 59. Market share of new U.S. light-duty vehicles by segment.

Figure 60. Historical sales-weighted average new U.S. light-duty vehicle weight 1975-2006.

While the shift from smaller vehicles to larger and heavier segments is partly responsible for the increasing average vehicle weight, weight increase within vehicle classes or segments is

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also taking place. For instance, the weight of a new Toyota Corolla recently introduced in the United States is about 100 kg heavier than the same model introduced 10 years ago (Figure 61).

One reason for this is “feature creep”; the increasing number of new features that have been introduced into vehicles that improve utility such as comfort and safety, which also add weight. Examples include power folding seats, heated seats, navigation systems, additional speakers, and safety features like side air bags.

Figure 61. Curb weight of Toyota Corolla models introduced in the United States, model years 1990-2006.

Increasing vehicle weight has not always been the trend. Between 1976 and 1982, automakers reduced the weight of the average new vehicle in response to the “energy crisis,” which saw sudden increases in fuel prices, gasoline lines and rationing, and the enactment of federal Corporate Average Fuel Economy (CAFE) regulations. They did so primarily by downsizing the fleet and by shifting from heavier body-on-frame to lighter-weight unibody

designs. With new U.S. CAFE standards now legislated, interest in vehicle weight reduction is expected to intensify.

6.2.1. EFFECTIVENESS OF VEHICLE WEIGHT REDUCTION

It is clear that vehicle weight reduction has the potential to reduce fuel consumption, but the precise relationship is not so obvious. Figure 62 plots the adjusted, combined city/highway (55/45) fuel consumption and curb weights of all model year 2005 light-duty vehicles offered

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in the United States, revealing a general positive correlation. On average across all available vehicle models, every 100 kg weight reduction will achieve a reduction of 0.69 L/100km in fuel consumption. While these figures are useful to detect a general trend, they are not normalized for performance, size, or other attributes.

Figure 62. Curb weight and fuel consumption of U.S. model year 2005 vehicles.

Many studies describe the vehicle fuel consumption reduction benefit associated with lightweighting [Wohlecker et al. 2007; NRC 2002]. The reported improvement in fuel consumption varies widely, from 4.5–8.0% for every 10% reduction in vehicle weight. Other studies report the benefit in absolute gains, where the improvement in fuel consumption ranges from 0.15–0.70 L/100km for every 100 kg of weight reduction. Factors that affect this relationship include the size and type of vehicle, the drive cycle used to evaluate the vehicle, and the powertrain.

We are primarily interested in the effect of vehicle weight reduction on its fuel consumption, at constant performance and size, for the average new vehicles being driven in the United States. To estimate this, simulations of representative vehicle models were run using AVL© ADVISOR vehicle simulation software. We selected the model year 2005 Toyota Camry and the Ford F-150, the best-selling vehicles in the United States, to represent the average car and light truck. The fuel consumption of these gasoline internal combustion engine vehicles were estimated from simulations that combine both city (FTP-75) and highway (HWFET)

drive cycle results. The simulations revealed that leaving vehicle acceleration performance and size unchanged, for every 100 kg weight reduction, the adjusted, combined city/highway

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fuel consumption could decrease by 0.40 L/100km for cars, and 0.49 L/100km for light trucks in the United States (see Figure 63). In other words, for every 10% weight reduction from the average new car or light truck’s weight, the vehicle’s fuel consumption reduced by 6.9% and 7.6%, respectively.

Figure 63. Simulation results: curb weight – fuel consumption relationship for today’s vehicles

6.3. How to reduce vehicle weight. Some strategies

6.3.1. VEHICLE WEIGHT REDUCTION BY LIGHTWEIGHT MATERIAL SUBSTITUTION

For an average vehicle, about three-quarters of its weight is incorporated in its powertrain, chassis, and body (Figure 64), and the bulk of this is made of ferrous metals. Other major materials found in an average automobile in the United States include aluminium and plastics or composites, as shown in Figure 65. This figure also shows how the use of aluminium and high-strength steel (HSS) as a percentage of total vehicle mass has been increasing over the past two decades, while the use of iron and mild steel has been declining.

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Figure 64. Vehicle mass distribution by subsystem.

Figure 65. Material composition of the average automobile in the U.S.

Aluminium and high-strength steel are two of several alternative lightweight materials that can be used to replace heavier steel and iron in the vehicle. Other material candidates include magnesium, and polymer composites such as glass- and carbon-fibre-reinforced thermosets and thermoplastics. The relevant properties of these materials are summarized in Chart 18 below, and are discussed in turn. More costly and rarer alternative materials, such as metal-matrix materials and titanium, are not considered.

Chart 18. Properties and prices of alternative lightweight automotive materials.

High-Strength Steels (HSS).

High-strength steels are manufactured using a combination of alloy compositions and processing methods to achieve high strength with almost the same formability as mild steel.

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HSS are a popular alternative automotive material because they make use of existing vehicle manufacturing infrastructure, and there is OEM support for near-term use. The challenge is to develop manufacturing technologies to make the production and use of these new materials economically viable on a high-volume scale, such as using tailored blanks and tube hydroforming. During the previous years, about one-fifth of the steel used in the average automobile is HSS, and this fraction has been increasing steadily. Using mostly dual-phase steel, the International Iron and Steel Institute’s Ultralight steel Auto Body (ULSAB) Program demonstrated mass savings of 25% for a C-class (compact) car’s body structure. HSS is an attractive nearer-term option, due to its relatively low cost and its accessibility.

Aluminium.

Nine percent of the mass of the average automobile in the United States is aluminium. Most of the aluminium is cast, and used mainly in the engine, wheels, transmission, and driveline. The stamped-sheet aluminium body of a car is more difficult to form than steel, and has to be handled with care to prevent scratches, because it is softer. Aluminium is a better conductor than steel, making it more difficult to spot weld, so it is more likely to use more laborious adhesive bonding rather than spot welding. Ducker Research projected that aluminium use in automotive applications would reach 144 kg per vehicle by 2010, but is unlikely to overtake steel, due to the higher cost of aluminium.

Magnesium.

Magnesium alloy is 30% less dense than aluminium and 75% lighter than steel components. It is also easier to manufacture, having a lower latent heat (it solidifies faster, and die life is extended), and being easier to machine. However, it has a lower ultimate tensile strength, fatigue strength, modulus, and hardness than aluminium. Promising automotive applications include structural components in which thin-walled magnesium die castings may be used. About 40% of magnesium in vehicles today is cast into instrument panels and cross car beams. Other applications include knee bolsters, seat frames, intake manifolds, and valve covers.

Magnesium content in vehicles was expected to grow from 3.5 kg today to 7.3 kg in 2010 [Ducker 2002]. The U.S. Automotive Materials Partnership (USAMP) announced an ambitious goal of raising this to almost 160 kg by 2020. However, factors limiting the growth

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of magnesium by the automotive industry include the development of creep-resistant alloys for high-temperature applications, improvements in the die casting quality and yield, corrosion issues, and the production of magnesium in sheet and extruded forms.

Polymer composites.

Plastics and polymer composites currently make up about 8% of a vehicle by weight and 50% by volume, and these numbers are expected to increase slowly. The main factors restricting the growth of polymer composites in vehicles today are the long production cycle times and the cost of the fibres. The most common type of automotive composites is glass fibre reinforced thermoplastic polypropylene, which is applied to rear hatches, roofs, door inner structures, door surrounds, and brackets for the instrument panel. Other types include glass mat thermoplastics, sheet moulding compounds made of glass fibre reinforced thermoset polyester, and bulk moulding compounds or glass fibre reinforced thermoset vinyl ester. Carbon fibre reinforced polymer (CFRP) composites are more expensive and less popular, although they offer significant strength and weight-saving benefit. The Rocky Mountain Institute’s mid-size concept Hypercar used CFRP to achieve a body-in-white weight that is 60% lighter than a conventional steel one [Lovins and Cramer 2004]. However, carbon fibres cost an inhibiting $13–$22 per kilogram, compared to $1–$11 per kilogram of glass fibres [Das 2001]. Use is typically restricted to low-volume applications in high-end luxury vehicles. One successful application in production vehicles is the carbon fibre drive shaft. Other technical challenges of using CFRP include the infrastructure to deliver large quantities of materials and the recycling of composites at the vehicle’s end of life.

To summarize the lightweight material candidates, a comparison of these options is given in Chart 19. Of the candidates, aluminium and HSS are more cost-effective at large production volume scales, and their increasing use in vehicles is likely to continue. Cast aluminium is most suited to replace cast iron components, stamped aluminium for stamped steel body panels, and HSS for structural steel parts. Polymer composites are also expected to replace some steel in the vehicle.

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Chart 19. Comparison of alternative lightweight automotive materials.

6.3.2. VEHICLE WEIGHT REDUCTION BY REDESIGN AND SECONDARY WEIGHT SAVINGS

On a component level, the amount of weight savings resulting from using alternative materials in any vehicle component depends on the application and design intent. For instance, for a body panel designed for strength and resistance to plastic deformation, 1 kg of aluminium can replace 3–4 kg of steel. For a structural component designed for stiffness in order to restrict deflection, 1 kg of aluminium replaces only 2 kg of steel. On a vehicle-level, with aggressive use of lightweight materials, net weight savings of 20–45% can be obtained, as has been demonstrated in a few concept vehicles (see Chart 20).

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Chart 20. Concept lightweight automobiles that embody lightweight materials.

Redesigning or reconfiguring the vehicle is another strategy to achieve weight savings. For example, a marked decline in vehicle weight in the early 1980s was partly achieved by changing some vehicles from a heavier body-on-frame to lighter-weight unibody designs. Although most cars already have a unibody design, the potential exists for smaller sport- utility vehicles to follow suit.

Another way to minimize weight with creative design and packaging is to minimize the exterior dimensions of the vehicle while maintaining the same interior space, or to remove features from the vehicle. Figure 66 plots the interior volume of various midsize sedans offered in model year 2007 with their curb weights, illustrating the potential weight savings using this approach. However, it is acknowledged that the need for safety features, either by regulation or consumer demand, may hinder lightweight vehicle design using this approach.

Figure 66. Potential weight savings from redesigning model year 2007/2008 midsize sedans while maintaining same interior volume.

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Secondary weight savings can also be realized by downsizing subsystems that depend on the total vehicle weight. As the vehicle weight decreases, the performance requirements of the engine, suspension, brake subsystems and others are lowered, and these can be resized accordingly.

Recently, researchers at the University of Michigan estimated a 1.25 factor for secondary, compounded weight savings by observing the mass of all subsystems in 35 different vehicle models. [Malen and Reddy 2007] That is, for every 1.00 kg initial mass change, an additional 1.25 kg of mass savings will be realized by resizing subsystems accordingly. It is acknowledged in this report that their approach does not normalize the data for other parameters, such as vehicle size or acceleration performance, which could lead to less optimistic weight savings. For example, simulations of the Toyota Camry reveal that if the car’s body weight is reduced by 100 kg using material substitution, the engine weight can be

lowered by only 9 kg while delivering the same vehicle acceleration performance.

Reviewing these novel design options, it is clear that the amount of weight savings using this approach is not easily quantified and depends on the final designs of subsystems and the entire vehicle. The amount of secondary weight savings possible by vehicle redesign was moderated; we assumed it to be half the benefit achieved with material substitution. So, for every incremental kilogram of weight reduction from material substitution, one can expect to achieve a further 0.5 kg weight savings with weight-minimizing redesign.

6.3.3. VEHICLE WEIGHT REDUCTION BY SIZE REDUCTION

Vehicle size reduction, the third way to reduce vehicle weight, is distinguished from the two weight-reduction approaches already discussed. Vehicle size generally correlates with weight. This can be seen in Figure 67, which shows vehicle size in terms of a modified footprint—its wheelbase multiplied by overall width—and curb weight of all model year 2005 light-duty vehicle models offered in the United States.

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Figure 67. Size (footprint) vs. weight of U.S. vehicles offered in model year 2005.

By shifting sales away from larger and heavier vehicle types, reduction in the sales weighted average new vehicle weight can be obtained. This can be done by:

1) Reversing the recent sales trend across vehicle segments towards larger vehicles, that is, selling more cars instead of light trucks for instance. 2) By downsizing vehicles within each vehicle segment— selling fewer large vehicles in each segment.

Figure 68 shows the 2005 sales distribution of new vehicles by a modified footprint measurement. The distributions are distinguished between the car and light truck segments. The average car (1,630 kg) weighs almost 25% less than the average light truck (2,140 kg).

Figure 68. U.S. light vehicle sales distribution in 2005 by size.

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Within the car segment, the average new U.S. car size as measured by interior volume (passenger plus cargo room) has remained relatively unchanged since the 1980s. The average car size decreased in the late 1970s as a response to the oil crisis, but returned close to the pre-crisis levels shortly after and has been growing slightly since (Figure 69). If large cars were downsized to midsize, and midsize to small (size classes as defined by U.S. EPA), weight savings of 9–12% could be achieved. For other vehicle segments including SUVs, minivans and pickups, weight savings of up to 26% can be seen, as shown in Figure 70.

Figure 69. Historical new U.S. car interior volume relative to 1977 values

Figure 70. Three-year (2005-2007) sales-weighted average U.S. vehicle weights by EPA size class.

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6.4. Brief discussion on safety

The discussion of vehicle light weighting is not complete without some mention of safety implications. There is much debate on this topic, and there are studies that indicate how drivers and occupants of smaller and lighter vehicles are at a greater risk in crashes than those in larger and heavier vehicles. The question of how vehicle weight reduction affects overall traffic safety is not as straightforward, however, and is confounded by other driver-, road-, and accident-related factors.

We believe that there will be little compromise in safety standards when reducing the weight and size of the vehicle, for two reasons. First, it is possible to design and build quality small vehicles with similar crashworthiness as larger and heavier ones. Use of new materials, such as aluminium and some composites designs, can offer superior crash energy absorption. By reinforcing the structural stiffness of the vehicle at critical points, including safety features such as side airbags, and introducing crumple zones to absorb energy in case of a collision, automakers are already making smaller cars that protect their occupants better. For example, the MINI Cooper scored 4 out of 5 stars in the U.S. National Highway Traffic Safety Administration frontal and side crash ratings.

Second, aside from the crashworthiness of the vehicle and driver safety, there are other facets of the traffic safety discussion to be considered, including rollover risk, aggressiveness of vehicles to other road users, and vehicle crash compatibility. Considering net or overall traffic safety, some of the larger and heavier SUVs and pickups can actually pose greater safety risks for their drivers and other road users [Ross et al. 2006]. Hence, there is little compromise in safety as vehicle weight and size is reduced, and safety for all might actually improve if the heaviest vehicles could be made lighter.

6.5. Cost of vehicle weight reduction

Cost is an important consideration, because we are interested in detailing the benefits associated with vehicle weight reduction at an acceptable cost of implementation. For weight reduction using lightweight materials, automakers have been reluctant to adopt new materials and manufacturing processes, in part because of the established infrastructure,

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capital equipment, and knowledge base to promote use of conventional materials, and also because of the cost of substituting these alternative lightweight materials.

Cost estimates of using lightweight automotive materials in the literature vary widely, from $1.20 to $13.70 per kilogram of weight savings. This is not surprising, since much depends on the type of lightweight material proposed, the vehicle component, assumptions made on the processing of the materials, and the production volume.

When comparing the use of lightweight materials in different vehicle components, we reiterate that the weight reduction benefit depends very much on the intended use and design.

So the substitution of a lightweight material, say aluminium, for steel brings about a wide possible range of weight reduction for different components. To get a sense of potential applications of lightweight materials in vehicles and their corresponding manufacturing (OEM) costs, results from different case studies available in the literature are summarized in Chart 21. Most of the case studies examined lightweight material applications in the body-in- white.

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Chart 21. Incremental manufacturing cost compared to conventional steel alternative.

In general, the cost of alternative lightweight automotive material technology per unit weight savings is lower for high-strength steel (HSS), and is followed by aluminium and polymer composites. Automotive composites remain prohibitively expensive given high raw material prices and long production cycle times. HSS and aluminium are likely to remain popular substitutes for steel in passenger vehicles in the near-term.

Given this review, we will assume a mid-range estimate of $3.00–$5.00 per kilogram of weight savings by material substitution. Costs will be on the lower end for early weight reduction, and increase as more aggressive weight reduction is sought. Vehicle redesign and size reduction are simply assumed to be cost-neutral with respect to manufacturing costs. We assume that design costs are already incorporated in the development of new vehicle models and the manufacturing costs of producing a smaller or larger vehicle do not differ

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much. As a result, the net cost of weight reduction by all three approaches would be $2.00– $3.50 per kilogram shaved off the average vehicle.

6.6. Summary on vehicle weight reduction

Reduction in vehicle size and weight can significantly reduce fuel consumption. Every 10% of weight reduced from the average new car or light truck can cut fuel consumption by around 7%. The three strategies to reduce weight are (1) lightweight material substitution, (2) vehicle design changes, and (3) vehicle downsizing.

When alternative materials are used to perform lightweighting, aluminium and high strength steel are more cost effective at large production scales. Plastics and polymer composites, which cost more, will likely take a smaller role. With aggressive material substitution, up to 20% of vehicle weight can be cut. Secondary weight savings can be realized by downsizing subsystems. It is also possible to reduce weight by redesigning or reconfiguring the vehicle.

Creative designs can minimize the exterior dimensions of the vehicle while maintaining the same interior space. Average vehicle weight can also be reduced by downsizing vehicles. That means selling more small vehicles and fewer large ones, both across and within vehicle segments. If a buyer were to choose a small car instead of a midsize, or a midsize instead of a large car, the vehicle’s weight could be reduced by 9% to 12%. For SUVs, minivans and pickups, the weight savings can reach 26%.

Based on these assessments of material substitution, vehicle redesign, and downsizing, weight reduction of 20-35% is possible by 2035. We estimate that weight reduction by all three approaches would cost $2 to $3.50 per kilogram of weight saved in the average vehicle.

6.7. Design guidelines derived from the contents in chapter 6.

There are several ways to reduce the sales-weighted average weight of new vehicles. Weight reduction can be achieved by a combination of:

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1. Lightweight material substitution 2. Redesigning the vehicle to minimize weight 3. Downsizing the new vehicle fleet by shifting sales away from larger and heavier vehicles.

The appropriateness of each one on the alternatives must be evaluated in the specific case.

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7. Crash compatibility for ELTVs

7.1. Introduction

This chapter presents the most relevant information and conclusions achieved in the project in the field of vehicle crashworthiness and crash compatibility. More detailed information is included in Deliverable 2.3.

ELTVs are intrinsically light (low mass), small in dimensions and, if homologated inside L7e category, free of compliance of most crash test standards. In consequence, vehicle crashworthiness needs to be considered as a separate and fundamental issue in the vehicle design process.

7.2. Collision mechanics

Before talking about crashworthiness and compatibility it is necessary to present some basic concepts about collision mechanics.

It is possible to calculate de deceleration experienced by two colliding cars using a simplified model, from the crush load at the interface of the two cars, as shown in Equation 1.

Equation 1

If a vehicle is heavier compared to the opponent, the lighter vehicle will experience higher deceleration level compared to the heavier. Using the law of conservation of momentum it is

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possible to calculate the change of velocity as shown in Equation 2 and Equation 3. The lighter vehicle will subject a higher total change of velocity than the heavier opponent.

Equation 2

Equation 3

In real collision the Δv will be heavier than in the value got in theoretical analysis due to the residual elasticity saved of the deformed structures. Frei considers in its Technical Paper [2] that the Δv is 5-10 % above the theoretical value.

7.3. Crashworthiness

Crashworthiness concept could be defined as the ability of a structure to protect its occupants during an impact. It could be considered as the ability to plastically deform and maintain a sufficient survival space for its occupants in crashes involving deceleration levels less than 40-50 g. To determine the crashworthiness of a structure the nature of the impact, is going to be one of the most important issues to be analysed.

7.4. Compatibility

Compatibility in collisions means that the different vehicles involved should deform at the same load level, yielding a length of the deformation zone proportional to the mass of the car. The total amount of energy that it is necessary to be absorbed is going to determinate the length of the crushable zone.

 To determinate the deformation length it is used frontal crash test against a rigid barrier with 50% overlap.  To determine the maximum load level at a given speed in a frontal collision, it is considered frontal crash test against rigid barrier with 100% overlap.

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The vehicle crash zone ought to be capable of absorbing its own kinetic energy in crashes with conditions comparable to crash against rigid barrier. In a collision against a heavier car, the heavier car experiences a smaller change of velocity than the change of velocity obtained in a test against a rigid barrier. Anyway some of the kinetic energy of the lighter vehicle it is going to be dissipated by the deformation of the heavier vehicle.

Vehicle compatibility in frontal crashes is influenced by three issues: mass ratios, structural properties and geometric properties [1]. The crash pulse, the intrusion experienced in the occupant compartments and consequently injured rates are affected by these properties. Vehicle mass and vehicle stiffness are going to be highly important and also have to be considered frontal height parameters in front-front crashes.

7.5. Example: differences between crashworthiness and compatibility

To understand the differences between the two concepts it is interesting to analyse the next example.

Two different vehicles are going to be tested in a frontal test against a rigid barrier, as is

shown in Figure 71. The masses of the vehicles are m1= 1300 kg and m2=1000 kg.

Figure 71. Frontal crash test against rigid barrier

It is going to be considered that the whole kinetic energy is going to be transformed in deformation work to finally get stopped.

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During the collision it is going to be considered that both vehicles have a lineal correlation between force and deformation as shown in Figure 72.

Figure 72. Force against deformation lineal correlation

At these conditions the deformation work it is going to be expressed as in Equation 4.

Equation 4

Considering that both vehicles are available to absorb its kinetic energy with a deformation in depth of 0.65 m after a frontal crash test of 50 km/h (13.89 m/s). It means that the force each vehicle it is going to support is different, as different are its masses, as it is shown at the equations below.

Equation 5

Equation 6

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Equation 7

Equation 8

Equation 9

Equation 10

The behaviour of both vehicles during the frontal crash test is shown in Figure 73. It shows how, for the same deformation, the force depends on the vehicle mass.

Figure 73. Force against deformation of each vehicle tested

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7.6. Frontal and lateral crashes

7.6.1. FRONTAL CRASHES

The most important factor governing vehicle performance is the collision type since it is going to determinate how two car’s structure will interact. Collision type will have a modifying influence on the effect of other parameters such as stiffness and geometry [7]. The effective global stiffness of a vehicle changes significantly from a full frontal impact to frontal offset impact. It is possible to attribute to the specific used for energy absorption and the fail modes.

According to Brewer [1], there are three parameters that are going to determinate the injury outcome of a front-front two-vehicle crash: crash-specific, vehicle specific and occupant- specific. Changing these parameters it is possible to improve compatibility of light vehicles.

Geometry

To perform a multitude functions and well crashworthiness car structures are good design. Car fronts often have local areas of stiff structure within a much larger area of weaker structure. This may result in penetration fork effect or over-ride. In these situations the vehicle's energy absorbing structure is ineffectively used, higher occupant compartment intrusions are often observed. In one reported offset frontal test between a small and medium sized car, the poor structural interaction masked the effect of mass and stiffness and dominated the outcome. It would be possible to correct this situation removing geometrical incompatibilities that allow the assessment of mass and stiffness influence.

Mass and structural stiffness

The risk of injury in the heavier car is lower than in the lighter car when two cars of different masses crash. It is necessary to note that mass must be considered a surrogate measure of other factors such as: vehicle size, length of front structure or presence of add-ons and safety features.

In order to limit occupant compartment intrusion in car to car frontal impacts, the crush zones of the vehicles involved, must be able to absorb the full energy of the impact.

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Two concepts may control global stiffness of the vehicle and improve compatibility: a “semi- rigid” passenger compartment or know the maximum crush force that must not be exceeded in an impact.

7.6.2. FRONT TO SIDE IMPACT

FUNDAMENTAL CONSIDERATION OF FRONT-TO-SIDE IMPACT

It is going to be considered that the front of vehicle 1 with a mass of m1 impacts with a

velocity of v on the side of vehicle 2 with a mass of m2. The deformation energy E is given by

Equation 11, considering that this impact is perfectly inelastic. E increases as m1/m2 increases, as shown in Figure 74.

When the force-deformation curves of both vehicles are known, the deformation of each vehicle in this impact is derived from the relation that the hatched area in Figure 75 is equal to E.

Equation 11

Figure 74. Normalized deformation energy(m1/m2=1) and mass ratio relation [3]

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Figure 75. Force versus deformation curves of striking and struck vehicles [3]

Example of Front of SUV to Side of Car impact tests [3]

Traffic accident data show that cars are apt to suffer greater damage than SUVs in front of SUV to side of car impacts. One of the reasons may be that the energy absorbing space in the car side is smaller than the energy absorbing space in the SUV front. On the other hand, it is assumed that the further improvement of SUV's partner-protection will lead to the further enhancement of vehicle safety performance in front-to-side impacts.

7.7. Design guidelines derived from the contents of chapter 7

7.7.1. INTERIOR GEOMETRY

Seating position must offer a good overview of the traffic situation for the driver to enhance active safety. It is got with a rather upright seating position. Also seating position results a little shorter ride-down distances for upper body parts.

Given an adequate restraint system, an upright position will reduce forward rotation of upper body parts and then decelerations will be lower, especially on the head.

Ergonomics considerations will determinate the position and angle of the steering wheel and the position of the feet and the knee bolster.

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7.7.2. RESTRAINT SYSTEM

It is necessary to provide an additional ride-down space in the vehicle interior according to the deceleration pulses shown in Figure 76. The components ought to deform ideally at a constant load level and the restraint systems must become active as soon as possible.

LMV

Compact Car

Figure 76. Schematic deceleration pulses against a rigid barrier at 56 km/h.

7.7.3. ABSORPTION OF COLLISION ENERGY

Low mass vehicles have small light drive trains. Most of the collision energy, lateral load components included, must be absorbed by front structure. Also it is necessary to avoid the deformation of the cabin and intrusion of components. It is necessary to design a deformable front structure which allows distributing energy absorption to all its structural elements.

7.7.4. STRUCTURAL CONCEPT

According to crashworthiness and compatibility criteria, it is necessary to integrate an structure which absorbs the energy produced in a collision in the frontal and lateral side of the vehicle, allowing a deformation level enough to avoid an intrusion in the cabin where the passenger are going to stay.

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The frontal structure should not be aggressive with other vehicles or pedestrians in crashes. And then it is necessary to considered geometrical compatibility with other vehicles. The deformation frontal area after an impact would be possible to be removed if the structure concept designed integrates modularity as well at the structure of the vehicle.

For ideal performance in a head-on crash, the principal energy-absorbing structures of each vehicle need to engage and remain engaged during the crash event. Then, if the front-end stiffness of the two vehicles are matched and are less stiff than the two occupant compartments, the front end of each vehicle will crush and reduce the risk of intrusion into either compartment. This will allow the restraint systems to provide effective protection. In front-to-side crashes, ideal performance is not as easy to define. Since the sides of vehicles provide very little crush space and are much “softer” than the front ends, matching both structure and stiffness becomes more challenging. Ideally a side-struck vehicle should have a self-protection system that includes a head protection airbag together with either padding or a torso airbag, and the structure should be sufficiently strong to reduce intrusion. Any intrusion that occurs should be uniform. Both front-end stiffness and geometry play roles in the crash incompatibilities between cars and light trucks. Countermeasures should address both aspects of design, starting with geometric mismatches because, if the principal energy- absorbing structures fail to engage in a crash, their stiffness become irrelevant.[4]

7.7.5. OTHER GENERAL CONSIDERATIONS

It is possible to design a better frontal structure of a light car which virtually eliminates over- riding. A good geometrical interaction may result in no significant over-riding, as shown in Figure 77.

Figure 77. Good interaction between frontal structures.

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When a small car is tested against an off-road vehicle, it is observed an intrusion at the facia level. Raising the car, it is possible to reduce the deformation of the facia level.

The first proposal of a 'semi-rigid' passenger compartment involves designing the vehicle in such a manner that the occupant compartment is sufficiently stiff, and then it can resist the deformation force put on it by any colliding car. This ensures that the impact energy is absorbed by the front structures of both cars.

The other concept has been made in which a limit is placed on the maximum crush force that must not be exceeded in a given impact. This concept has been extended with suggestions being made that both maximum and minimum force requirements are needed or that force corridors should be defined. Both proposals are effectively equivalent to controlling the vehicle's stiffness.

One of ways to enhance structural interaction in car-to-SUV frontal impacts is to install a SEAS (Secondary Energy Absorbing Structure) below SUV's front longitudinal member. Lowering SUV's front longitudinal member height and bumper beam height may enhance SUV's partner protection in front-to-side impacts.

The effect of engaging the SEAS of SUV with the body-sill of car on helping improve SUV's partner-protection in front-to-side impacts was comparatively small. But there is a possibility that it may become more effective due to the design improvement, which enhances the engagement between SUV’s SEAS and the car’s body-sill. In front to- front impacts, installing a SEAS on SUVs may enhance structural interaction. Therefore, considering both front-to- front and front-to-side compatibility, car’s body-side lower structure, which helps engage with SUV’s SEAS, should be studied.

SUV's lateral structure between front longitudinal members is expected to help improve the robustness of SUV's partner-protection in front-to-side impacts on the horizontal impact point change.

It should be considered in case of reviewing the design philosophy for both front-to-front and front-to-side impact compatibility.

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7.8. References

[1] Brewer, J.C., Smith, D.L.; “Preliminary Evaluation Methodology in Front-Front Vehicle Compatibility”; SAE Technical Paper; 2008-01-0814; 2008; Michigan; U.S.A. [2] Frei, P., Kaeser, R., Hafner, R., Schmid, M., Dragan, A., Wingeier, L., Muser, M.H.; Niederer, P.F., Wlz, F.H., “Crashworthiness and Compatibility of Low Mass Vehicles in Collisions”, SAE Techical Paper 970122 1997, Michigan, U.S.A. [3] Hirayama, s., Umakoshi, T., Morimoto, T., Obayashi, K., Okabe, T., “Research on Compatibility in Front-to-Side Impacts”, SAE Technical Paper 2005-01-1377, ISSN 0148-7191, 2005, Michigan, U.S.A. [4] O’Neil, B., Kyrychenko, S. Y., “Crash Incompatibilities Between Cars and Light Trucks: Issues and Potential Countermeasures”, SAE Technical Paper 2004-01-1166, ISBN 0- 7680-1319-4, 2004, Michigan, U.S.A. [5] Saunders, J., Smith, D. L., Barsan, A., “Restraint Robustness in Frontal Crashes”, SAE Technical Paper 2007-01-1181, ISSN 0148-7191, 2007, Michigan, U.S.A. [6] Warner, C. Y., Warner, M. H., Benson, N. H., “Load Path Considerations for Side Crash Compatibility”, SAE Technical Paper 2007-01-1176, ISSN 0148-7191, 2007, Michigan, U.S.A. [7] Wykes, N. J., Edwards, M.J, Hobbs, C. A., “Compatibility requirements for cars in frontal and side impact”, SAE Technical Paper 986059- Paper Number 98-S3-O-04, 1998

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8. Add-ons and/or energy absorbers

8.1. Introduction

This chapter covers two issues. The first one is related to the effect of the presence of energy absorbers in the event of a crash. The second issue contemplates the recommendation, taken from the results of APROSYS project, of the most suitable add-ons to be integrated in OPTIBODY’s ELTV.

8.2. OPTIBODY concept for passive safety.

The basic idea for the global behaviour of OPTIBODY concept is shown in Figure 78:

Figure 78. OPTIBODY concept: passive safety enhancement derived from the availability of new spaces at the front of EVs.

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Expressed in a simple way, Figure 78 means that, for the new ELTVs (EVs in general), it is possible to increase passive safety by the modification of the vehicle fronts. In EVs, the vehicle front can be emptied from powertrain devices and components, especially if in-wheel motors are used.

The new design opportunities considered in OPTIBODY contemplate the installation of bigger energy absorbers. Energy absorption means, in this case, larger deformations. The vehicle can be modelled as a stack of at least, three different layers.

Layer 3 is the most external one. It is the part of the vehicle that first become in contact with colliding vehicles, objects or pedestrians. Basic specifications for this layer are that it must be able to absorb energy in case of a very low speed impact (5 km/h) and it must ensure pedestrian protection in case of overrun. These two functions are to be done by a structural component called add-on. To illustrate the concept of add-on, please refer to Figure 91 and Figure 88.

Layer 2 is formed by the intermediate elements in-between the external add-on and the vehicle chassis. The basic specifications for this subsystem are that it must support the add- on and it must absorb the energy of a mid-speed impact (15 km/h).

Layer 1 is the vehicle chassis. It has many functions, as it is the basic supporting structure of the whole vehicle. Concerning passive safety, it must absorb the energy of a high-speed impact (30 km/h).

Note:

Speeds of 5, 15 and 30 km/h are considered because they represent the most probable impact speeds in urban driving: 5 km/h (low-speed), 15 km/h medium speed, 30 km/h (high- speed). This speed grading will be kept as reference in the rest of the project.

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8.3. The function and behaviour of a stack of energy absorbers in a crash. Model and simulation results

As explained in the previous section, the vehicle is considered as a stack of three different layers. For a deeper understanding of the joint behaviour of the three layers, two simulation cases are developed in the following sections.

8.3.1. CONCEPTUAL MODEL FOR THE COMPARATIVE CRASH ANALYSIS

Figure 79 shows the conceptual model used for the crash simulations developed in the following sections. As explained in section 8.2, the vehicle front is considered as a stacking formed by three layers.

In the event of an impact or crash, depending on the physical characteristics of the real part forming the layer, each layer will deform, absorbing a determined amount of energy. As detailed in section 8.2, it is an objective that each layer absorbs the kinetic energy of an impact at the specified speed grading: 5, 15 and 30 km/h.

In order to analyse the joint crash-behaviour of a 3-layer structure, some simulation cases are presented. The calculation model used is detailed in Figure 79. The amount of energy absorbed by each layer (for a fixed geometry) depends on its stiffness, which in turns, depends on the material’s Young Modulus. Two simulation cases are developed:

 Case 1 simulates an impact of a mass of 50, 100 and 200 kg against a three- layer body. The most external layer (layer 3) represents the add-on. In this case, layer 3 is formed by a soft material with a Young Modulus of 35 MPa. The graphs showing the energy absorbed in each impact are given in Figure 81.  Case 2 simulates an impact of a mass of 50, 100 and 200 kg against a three- layer body. The most external layer (layer 3) represents the add-on. In this case, layer 3 is formed by a soft material with a Young Modulus of 10 MPa. The graphs showing the energy absorbed in each impact are given in Figure 83Figure 82.

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Comparative crash analysis:

Impacting Rigid element: Material 3: less rigid than aluminium Mass = 50, 100, 200 kg v Initial velocity = 30 m/s Material 2: aluminium

Material 1: steel

Constrained displacements

Figure 79. FEM model to analyse the effect on energy absorbers on the main vehicle structure.

8.3.2. SIMULATION CASE 1

Chart 22 specifies the characteristics of the material forming the 3 layers of the stack shown in Figure 79. Material no. 3 represents the material forming the frontal add-on of OPTIBODY vehicle. In this case, this material is quite “stiff” (Young Modulus = 35 MPa).

The stack is impacted by a mass of 50 kg, 100 kg and 200 kg. The deformed stack after each impact is shown in Figure 80. Finally, the energy absorbed by each layer is given in Figure 81. The analysis of the results, compared to those obtained in section 8.3.3, is presented in section 8.3.4.

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Case 1:

Tensile Tensile Young Strength Strength Elongation Density Material Modulus at Break Bar mass Yield 0.2% Ultimate (kg/m3) (MPa) (º/ ) (MPa) (MPa) 1 Material 1: 210 360 440 0.29 7800 82 % Steel Material 2: 70 145 186 0.22 2700 15 % Aluminium

Material 3 35 100 120 0.22 1100 3%

Chart 22. Main materials characteristics for case 1.

Case 1:

Impacting mass = 50 kg

Impacting mass = 100 kg

Impacting mass = 200 kg

Figure 80. Deformed stack after the impact of three different masses.

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Case 1: Internal energy (J)

Impacting mass = 50 kg

Emat3 ≈ Emat2

Impacting mass = 100 kg

Emat3 < Emat2

Impacting mass = 200 kg

Emat3 << Emat2

Figure 81. Simulation results: graphic representation of the energy absorbed by each layer in the stack

8.3.3. SIMULATION CASE 2

Chart 23 specifies the characteristics of the material forming the 3 layers of the stack shown in Figure 79. Material no. 3 represents the material forming the frontal add-on of OPTIBODY vehicle. In this case, this material is quite “soft” (Young Modulus = 10 MPa).

The stack is impacted by a mass of 50 kg, 100 kg and 200 kg. The deformed stack after each impact is shown in Figure 82. Finally, the energy absorbed by each layer is given in Figure 83. The analysis of the results, compared to those obtained in section 8.3.2, is presented in section 8.3.4.

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Case 2: material 3 with lower rigidity and mechanical properties

Tensile Tensile Young Strength Strength Elongation Density Material Modulus at Break Bar mass Yield 0.2% Ultimate (kg/m3) (MPa) (º/ ) (MPa) (MPa) 1 Material 1: 210 360 440 0.29 7800 82 % Steel Material 2: 70 145 186 0.22 2700 15 % Aluminium

Material 3 10 70 90 0.22 1100 3%

Chart 23. Main materials characteristics for case 1.

Case 2:

Impacting mass = 50 kg

Impacting mass = 100 kg

Impacting mass = 200 kg

Figure 82. Deformed stack after the impact of three different masses.

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Case 2: Internal energy (J)

Impacting mass = 50 kg

Emat3 >> Emat2

Impacting mass = 100 kg

Emat3 > Emat2

Impacting mass = 200 kg

Emat3 << Emat2

Figure 83. Simulation results: graphic representation of the energy absorbed by each layer in the stack

8.3.4. RESULTS DISCUSSION AND CONCLUSION

Simulation cases 1 and 2 show how, in the event of a collision, the amount of the energy absorbed by each layer can be controlled and modulated (within certain limits) as function of the layer stiffness, which in turns depends on the shape and material Young Modulus.

In case 1, layer 3 (the most external one, representing the frontal add-on), is done with a stiff material (Young Modulus = 35 MPa). In case 2, it is done with a softer material (Young Modulus = 10 MPa). Layers 2 and 3 remains the same in both cases.

For a better understanding of the results in Figure 81 and Figure 83, let’s take the event of the impact of the intermediate mass (100 kg). Main results are given in Chart 24:

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LAYER CASE 1 CASE 2 ENERGY ABSORBED (kJ) ENERGY ABSORBED (kJ) (layer 3 stiff) (layer 3 soft) Layer 1 0 0 Layer 2 25 18 Layer 3 18 25

Chart 24. Summary of energy absorption (rounded figures), cases 1 and 2, impact mass = 100 kg.

Data in Chart 24 show how the amount of energy absorbed depends on the material stiffness. A deformable layer 3 (soft) is able to absorb more energy (case 2), leaving less for the rest of the layers. As layer 3 is in both cases extremely stiff, it can hardly absorb any energy.

There is a physical limit in the maximum possible deformation of a determined part. In addition, a part made of a material too soft would need a very large deformation to absorb a reasonable amount of energy. In consequence, in the design of the frontal add-on, there must be a balance between material, shape and dimensions.

8.4. Preliminary design guidelines for the frontal add-on

8.4.1. INTRODUCTION

The chassis design was the starting point for defining the global dimensions of the frontal add-on. Figure 84 below shows the initial chassis design.

Note: the total vehicle length will not exceed 4 m in any case.

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159

203

125

454.35 400

Figure 84. Vehicle main dimensions

OPTIBODY vehicle is defined as "Category L7": A vehicle with four wheels, other than that classified for the category L6, whose unladen mass is not more than 400 kg (550 kg for vehicles intended for carrying goods), not including the mass of batteries in the case of electric vehicles and whose maximum continuous rated power does not exceed 15 kW.

8.4.2. APPLICABLE REGULATIONS

Regulation 125: Uniform provisions concerning the approval of motor vehicles with regard to the forward field of vision of the motor vehicle driver: M1

Similar to Directive 77/649/EEC (for M1 Vehicles). Some paragraphs from the directive are literally transcribed:

5.1. Driver's field of vision

5.1.1. The transparent area of the windscreen must include at least the windscreen datum points; these are:

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5.1.1.1. a horizontal datum point forward of V1 and 17º above to the left

5.1.1.2. an upper vertical datum point forward of V1 and 7º above the horizontal. However, this angle shall be reduced to 5º until September 30, 1981.

5.1.1.3. a lower vertical datum point forward of V2 and 5º below the horizontal.

5.1.1.4. to verify compliance with the forward-vision requirement on the opposite half of the windscreen, three additional datum points, symmetrical to the points defined in 5.1.1.1 to 5.1.1.3 in relation to the median longitudinal plane of the vehicle, are obtained

Figure 85. Determination of V points

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ECE/TRANS/180/Add.9:

According to ECE/TRANS/180/Add.9 (Global technical regulation No. 9, PEDESTRIAN SAFETY), a headform impact test is defined to improve pedestrian protection in car accidents. Two possibilities are described: Child headform impact (3.5 kg) and adult headform impact (4.5 kg), both impacting the car bonnet at 9.7 m/s, the first one with an angle of 50º to the horizontal and the second with an angle of 65º to the horizontal. Therefore two areas or impact are defined in the bonnet as showed below. HIC15 must not exceed 1,000 over one half of the child headform test area and must not exceed 1,000 over two thirds of the combined child and adult headform test areas. The HIC15 for the remaining areas must not exceed 1,700 for both headforms.

7 7

Figure 86. Headform impact test

ECE/TRANS/WP.29/78/Rev.2: Consolidated Resolution on the Construction of Vehicles (R.E.3), June 2011

Some relevant paragraphs of the standard are literally transcribed:

2.8.3.1. "Approach angle" – see Standard ISO 612:1978, term No. 6.10: At least 25º for off-road vehicles

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Figure 87. Definition of the approach angle for vehicles, according to ISO 612:1978

8.37. Protection of pedestrians and other vulnerable road users in the event of a (head- on) collision with a passenger car

The following text is intended to provide motor vehicle manufacturers with guidelines concerning the design of future vehicle types and, in particular, the qualitative characteristics of the structure and deformation capacity of the front section of passenger cars; its purpose is to reduce as much as possible the severity of the injuries sustained by a person struck by the front of a vehicle travelling at a speed of up to 40 km/h.

8.37.1. Area of initial impact

The area of initial contact with the legs of the person struck should be below and forward of the conventional bumper. It should extend over a vertical height sufficient to distribute the force over the legs, preferably below the knees of an adult person.

8.37.2. Front structure of the vehicle

8.37.2.1. The rear third of the bonnet, the windscreen frame and the front pillars (A) should receive particular attention as regards both their energy-absorption capacity and their form. It should not be possible for the head to strike the windscreen-wiper pivots. Should such contact be possible, the windscreen-wiper pivots shall have a suitable protective covering.

8.37.2.2. The bonnet leading edge should be such that the impact should not be against a hard edge but against a structure which is sufficiently large and if possible energy- absorbent.

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8.37.2.3. An adequate deformation of the front third of the bonnet would, in particular, reduce the severity of head injuries to children.

8.37.2.4. Rigid parts located under the bonnet should be placed some distance back so as to allow sufficient deformation of the bonnet on impact.

8.37.3. Headlamps and other lamps

Headlamps and other front lamps should not have rigid projecting frames. If possible, they should be mounted slightly recessed in the bodywork.

8.37.4. Accessories

External accessories (trimmings, spoilers, etc.) should be deformable, retractable or detachable so as to minimize the risk of injury. In the latter cases, these recommendations shall also apply to the residual parts.

8.37.5. Structural elements

8.37.5.1. Preference should be given to structures with adequate energy-absorption capacity.

8.37.5.2. The curvature radius of parts of the vehicle which may be impacted should be as large as possible, with due account being taken of technical requirements.

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8.4.3. FRONTAL ADD-ON POSITION ON THE CHASSIS

As explained in section 8.2, the frontal add-on is the most external layer of the vehicle. In consequence, it is the first element that enters in contact with colliding objects or persons. Position (Figure 88) and dimensions are determined by:

 Its energy absorption capacity  Requirements for its attachment to the vehicle  Other functional requirements, as those related to the driver field of vision (Figure 89) and pedestrian impact (Figure 90).

Figure 88. Position of the front add-on in the chassis.

Driver field of vision according to Directive 77/649/EEC and the position of the add-on over the chassis, according to the requirements in this directive are shown in Figure 89:

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H point

Figure 89. Driver field of vision according to Directive 77/649/EEC.

Pedestrian frontal impact (centered):

It was considered a hybrid III 50th male dummy for a frontal centered impact. As shown in the figures below, the add-on geometry tries to avoid a direct impact of the head against the cabin or the windscreen. The APROSYS European project considerations concerning the deflection of the pedestrian to one side of the road in case of a pedestrian frontal impact were also taken into account: a rounded circular shape was adopted in the contact area with the legs.

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Figure 90. Dimensioning for optimal pedestrian impact.

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8.4.4. ADD-ON INITIAL CONFIGURATIONS AND DESIGNS

The following step is to analyse different initial designs and configurations for the construction of the add-on. At first, it has been adopted a configuration of a glass-fibre skin (3 layers, thickness 0.4 mm) with an internal foam (60 mm thick). A parametric analysis, changing dimensions, materials and mesh parameters will be carried out. These different configurations will be checked in crash simulations with an impactor with a mass of 20 kg launched against different spot on the add-on. The add-on energy absorption capacity and the deceleration values obtained in the accelerometer located inside the impactor will be analysed for each configuration. The optimum configuration will correspond to a high energy absorption capacity combined with a low HIC15 value at the impactor.

Note:

This impact test is defined in this way because it corresponds to the testing equipment available at the UNIZAR labs. Latter in the project, the results obtained from simulation will be validated.

Figure 91 shows the main dimension of a front add-on to be installed in OPTIBODY vehicle, as it is described in Figure 84. This preliminary design is based on the specifications and recommendation from:

- Aprosys project. - Standards in section 8.4.2

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28º

R200

R500

1234

814

60

Figure 91. Main dimension of the front add-on

Add-on construction material: foam

It is proposed the construction with Polyurethane PUR 100 (LS DYNA material model: crushable foam). The main material properties are:

 Foam thickness = 60 mm  Foam weight = 18.63 kg  Density = 100 kg/m3

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Figure 92. Stress-strain curve considered for PUR 100:

Foam mesh model (solid elements):

Figure 93. FEM model of the frontal add-on with solid elements

Skin

The main add-on skin properties are listed below:

 Glass fiber, 3 layers 0/90/0, 0.4 mm thick each layer  (LS DYNA material model: enhanced composite damage)

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 Skin thickness = 2.1 mm  Skin weight = 11.08 kg  Density = 1584 kg/m3

 EA = EB = 14 GPa

 GAB = 2.07 GPa  μ = 0.148

 Xc = -0.196 GPa

 Xt = 0.196 GPa

 Yc = -0.180 GPa

 Yt = 0.180 GPa

 Sxy =0.045 GPa

Skin mesh model (shell elements):

Figure 94. Add-on skin FEM model using shell elements

Add-on total weight = 29.72 kg

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8.4.5. IMPACT TEST SIMULATION

This section presents the results of an impact test simulation. This case used the add-on definition properties detailed in the previous section.

 Impactor weight = 20 kg  Impactor velocity = 5.44 m/s

Constrained

v

Figure 95. Simulation case: main dimensions

Simulation results

The main results obtained from the simulation are shown in Figure 96 to Figure 98.

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Figure 96. Deformed configuration at 55 ms

Figure 97. Energies (global)

Figure 98. Acceleration at the impactor’s accelerometer

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Note:

The front add-on will be attached to the vehicle chassis in the spots indicated in Figure 99 and Figure 100.

Figure 99. Upper joint to the chassis.

Figure 100. Bottom joint to the chassis.

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9. Maintainability

9.1. Introduction

Vehicle maintenance is one of the most important tasks during the product lifecycle. If correctly and appropriately done, it extends the life of the vehicle, its energy efficiency and improves the safe driving, preventing accidents and damage to persons.

Electric vehicle differs greatly from internal combustion vehicle with regard to the components that form the motor, so maintenance should be studied separating the parts in common with the internal combustion vehicles and the new elements. The reduction of moving parts and the needs of refrigerant fluids may reduce the maintenance requirements and could make it easier to repair.

Countries like Canada and USA, in North America, or Sweden and UK, in Europe, have investigated the development of the tests in models of electric vehicles, to see first the results that these types of vehicles provide in the market currently.

This article reviews the maintenance developed on electric vehicle fleets, studied by institutes such as INL (Idaho National Laboratory), DOE (Department of Energy) or European projects, as well as the analysis of elements that represent the most important components of the electric vehicle.

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9.2. Background

Electric vehicle represents a revolution in the present mobility of the fleet worldwide, in order to reduce the polluting gas emissions and improve the energy efficiency. To this end, governments of the main developed countries have pledged to reach 20 million of EV by 2020 (IEA, 2011). Although the development of this technology is not as implemented as the internal combustion engines, the policies promoted by the European Union are focused to implement this field in the market, with the introduction of the EV and the PHEV, to replace fossil fuel vehicles.

During the nineties there was a commitment to develop the EV by some auto companies. Chevrolet developed the S-10 model (which was tested in several studies), GM the EV-1 model, Ford the Ranger pickup model, and not just American companies developed this vehicle, but one of the main promoters of electric vehicles was the Japanese multinational Toyota, which had the RAV4 EV model. Tesla focused on developing an electric sports car, the Roadster, capable of achieving the same performance as a sport car with its features and a range of 400 km with lithium-ion battery.

Currently many EV models are developed, by established brands such as Mitsubishi with its iMiEV and Nissan with its Leaf and by new multinationals from emerging countries like India, with the development of its model Revai.

The increment in the number of electric vehicles is based on the development of new technologies that lower the costs of production and the rising of the price of fossil fuel. Smart Move (2011) conducted an economic study to analyse the profitability of electric vehicles compared to diesel vehicles, taking into account the current price of each vehicle, and a probable hypothesis that increased fuel prices, from the fifth year the electric vehicle is more profitable than a conventional diesel vehicle with the same characteristics.

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9.3. Analysis of electric vehicle fleets

9.3.1. UNITED STATES OF AMERICA (USA)

USA is a pioneer in the development of electric vehicles, as a commitment to the future in the use of electric vehicles in urban fleets, since the EVs suit the technical characteristics required by the vehicles used by these fleets.

The Department of Energy (DOE) has pledged its commitment to the development of electric vehicles. In cooperation with the INL (Idaho National Laboratory), a wide range of vehicles has been tested since the 90's, so it has a great experience in this issue, assessing each vehicle in different weather conditions and characteristics to which the vehicle must adapt.

In 1996, the DOE, in its program of operations, introduced a group of electric vehicles, Toyota RAV4 EV, Ford Ranger and Chevrolet S-10, in the state-owned fleets in order to verify first-hand the performance and reliability in these models. They were tested in the Southern California Edison Company, and they were also tested in a consortium of companies made up of PEPCO (Potomac Electric Company), APS (Arizona Public Service Company), Salt River and ETA (Electric Transportation Applications).

When completed the first tests, several conclusions were obtained about the maintenance of this type of vehicles, where the main problems were related to the batteries, from their malfunctioning in the charge to entire broken modules, forcing the replacement of these elements. These problems were given throughout the tests, since they are first-generation vehicles, which have not yet been evolved to its maximum performance.

Figure 101 shows the results of the tests for two models: 10 units of the Toyota Rav4 EV and 7 units of the Ford Ranger, as representative samples of the entire group.

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Figure 101. Maintainability Toyota Rav4 EV and Ford Ranger. Source: Own elaboration, INL (2000)

9.3.2. US POSTAL SERVICE

The DOE set a large number of electric vehicles aside for the U.S. Postal Service, since the technical features offered by electric vehicles suit the needs of the U.S. Postal Service: a cruising range of around 100 miles per charge and urban speed. The average distance travelled by the delivery services in this study were 10 miles per day per vehicle and the total distance travelled by the entire fleet is two million miles.

Between February 2001 and October 2002, 22 urban delivery vehicles were operating, but the goal is to reach 500 units in total. All of them were tested and analyzed in different tests comprising its carrying capacity, cruising range, acceleration, maximum speed and electric consumption. Like any conventional vehicle, it was necessary to put into practice some maintenance actions to ensure the functionality of the vehicle. Two vehicles were taken as reference for the reliability analysis, extracting from them the following results, shown in Chart 25.

Component Number of Incidents Vehicle No. 1 Vehicle No. 2

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Traction Battery 5 2 Charging System 2 2 DC/DC Converter 1 Battery Control Module 1 Power Steering 1 Shift Indicator 1

Chart 25. Maintainability of US Postal Service. Source: M. Wehrey, (2001)

Maintenance operations represented a time of completion that carries a temporary downtime of the vehicle. The percentage of time these two vehicles were available, between August 2000 and December 2011, was 97.5% and 98.6% respectively. Technology installed in these vehicles is a 90 HP AC induction in the rear axe. Regarding the storage of energy, it has 39 lead-acid batteries of 8 volts each, and weighing approximately 900 kg.

Then, a larger study was performed with this type of fleet, which includes 500 vehicles tested in more than twenty post offices, since the results suits better, making a more representative sample of all the maintenance operations. Figure 102 shows these data, but it excludes from the sample operations prior to the delivery of vehicles by Ford, which consisted of replacing all the batteries to all the vehicles. Reliability of these vehicles ranged in 99%, exceeding the availability of such vehicles powered by internal combustion, between 97-99%. Over time, the use of vehicles decreased the availability, but without ever reaching 97%.

Figure 102. Maintainability 500 vehicle fleet US postal. Source: Ryerson, Master and Associates, Inc., 2003

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At present new models have been developed, increasing their autonomy and performance. The architecture of each vehicle differs from the rest in order to find the best configuration to suit the needs of the fleet. Thus there are different configurations that include DC and AC motors, as different lithium-ion batteries or Zebra. Figure 103 shows different architectures of these models, which are currently being evaluated, so their results are not yet available.

Figure 103. Architecture of new US postal delivery van. Source: Jones 2010

9.3.3. SITE OPERATOR PROGRAM

Site Operator Program is an evaluation and testing program that analyzes electric vehicles, funded by U.S. Department of Energy and developed by Idaho National Engineering and Environmental Laboratory. Between 1992 and 1996, a fleet of over 250 electric vehicles was tested and analyzed, of whom only 50 vehicles belonged to a new generation. The fleet was tested in fourteen companies across the U.S., and the vehicles were used in areas such as education, federal agencies, and utilities. Among other models, the Toyota RAV4 EV, Ford Ranger and Chevrolet s-10 were studied. Site Operator Program was intended to improve the electric vehicle research, increase the energy supply network and ensure the reliability and public acceptance of the EV.

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Although the maintenance of electric vehicle is lower than combustion vehicles, the time of repair and maintenance it is higher, reducing the vehicle uptime greatly.

The general conclusions to this study show that the battery is a limiting factor in terms of loading and autonomy of vehicles. The climate greatly influenced in vehicles. Converting internal combustion vehicles (ICE) to electric vehicles has a large influence on the durability of other components as they are being subjected to efforts they have not been designed to, being reduced drastically.

For example, in Arizona, the high cost of maintenance of some vehicles, together with its low performance and reliability they represented, caused five of the twenty cars (two Unique Sedan and three Soleq EVcorts) were removed from the study. These vehicles offered low autonomy and/or low acceleration, incompatible with the development of this new technology. Regarding the maintenance costs they represented, compared to the energy supplied, the largest percentage was related to the maintenance, in some cases representing 90% of the specific cost.

9.3.4. HYUNDAI SANTA FE FLEET IN HAWAII

Hawaii is an archipelago located in the North Pacific Ocean. It has a mild climate and its topography is characteristic of volcanic islands, so there are no large motorized routes. This peculiarity make it ideal for electric vehicles, since the possibility of long routes is zero, being a representation of short routes for short periods of time.

Between July 2001 and June 2003, fifteen Hyundai Santa Fe models were tested to evaluate their incorporation into the Honolulu electric company. All of these vehicles accumulated over 255,000 km in 25,000 trip, with an average of 10.2 km/trip. The models used are conventional Hyundai Santa Fe models, converted into electric motors with 60 kW Panasonic NiMH batteries.

The conclusions of the study show that a fast battery charge increases the energy efficiency. It also sets different driving patterns to find that the energy efficiency (kWh/km) is higher in highway driving at high speeds, whereas if the vehicle is driven in urban areas, with high number of stop & go, this efficiency decreases sharply.

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Another study on the same car tried to find a model with which to establish usage patterns and thus anticipating the battery degradation and prevent its premature wear. The same fifteen Hyundai Santa Fe models were tested with different battery configurations to reach the correct characterization of the battery. The main conclusion in this study was that it is possible to find a model that anticipates the premature wear and establish a preventive maintenance system.

9.3.5. NEIGHBOURHOOD ELECTRIC VEHICLE (NEV)

Electric car is not only directed toward conventional use, but its developing and evolving has a background on vehicles intended to be used this way, which is known as a NEV. NEV has some characteristics similar to the ones currently offered by the EV. They are light vehicles (less than 900 kg), wheel motors powered by a low speed range, do not exceed 20-25 mph, used for short journeys.

The DOE studied in 1996 several NEVs in order to set up a guide for NEVs, establishing a fleet of such vehicles. It studied 101 different NEV models, travelling 168,419 miles in five government and private fleets. Fleet Maintenance is an important issue, being more important in those fleets with a higher use. Many NEVs did not have preventive maintenance measures, which anticipate the temporarily down from the vehicle, increasing significantly the time out of service.

Two types of maintenance must be distinguished: preventive and corrective maintenance. Preventive maintenance anticipates the fault and corrective maintenance repairs the element after the failure. In order to establish preventive maintenance, it is necessary to know the most common faults, which are usually located in the batteries. The batteries go flats during long periods of time out of service, so it is necessary to install a switch to disconnect the circuit when the vehicle is to be out of service for several days. If not, the battery will go flat to levels near zero so the battery pack must be submitted to loading tasks and preventive maintenance such as filling the water drums. A few vehicles did not travel lengths large enough to require maintenance associated with the replacement of the wear, such as tires or brakes review. Only the tires were replaced due to the solar radiation on the tire sidewall.

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Most corrective maintenance measures are focused on the battery, such as deep discharge due to long periods of inactivity. Battery’s lifetime is estimated at 3 years with the appropriate preventive maintenance. When the engine is submitted to severe needs, overheating occurs and the equipment fails. However, other failures, located in the power controller or the power converter, appears for no apparent reason. Environment produces corrosion in elements that are not properly sealed.

Availability of spare parts, qualified technicians and facilities maintenance, are often a problem which reduces the vehicle’s availability.

Maintenance costs involved in NEVs depends heavily on anticipating failures. Battery filling ensures compliance lifecycle, saving cost of a new battery, between $ 500 and $ 1000. Developments of new models improve the performance, increasing the equipment lifetime and correcting mistakes from previous versions.

9.3.6. FORD THINK CITY

The multinational Ford, along with the DOE, developed in October 2001 a lease program to develop driving and reliability tests in a new electric model, the Ford THiNK City. This model was tested in different places with an initial fleet of 376 electric vehicles. This number was gradually reduced until April 2005, when there was no vehicle being tested.

The Ford THiNK City is a NEV, an electric vehicle to be used essentially in urban neighbourhoods, with low speed requirements and low daily distances travelled. The 1999 year model was equipped with an AC induction electric motor with a power of 27 kW, and NiCd batteries, while other more developed models in 2008, are equipped with an induction motor of 34 kW, equivalent to 46 horses power, and Zebra batteries (24 kWh) or Li-Ion (23 kWh), which provide it with greater autonomy and maximum speed.

Tests to electric vehicles were conducted in various U.S. states like California (192), New York (109), Michigan (52) and Georgia (16), and 7 vehicles were tested outside of U.S., six electric vehicles in Canada and one more in Bermudas. The total amount of the electric fleet was 376 vehicles, which travelled 1,755,701 miles.

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For example, in the city of New York, the NYPA (New York Power Authority), included in its program a total of 97 vehicles to be part of the test. In May 2004, 24 of them had already returned to the factories of the company and they would never join the project. The most important reasons were mainly due to lack of leasing, dissatisfaction with the performance of the vehicle, etc. The preventive maintenance represented the 47% of the total maintenance operations, while repairs represented the remaining 53% of the operations on tested vehicles. Figure 104 shows all the maintenance operations, including refills failures, both at home such as in service stations, or repair of damaged parts.

Figure 104. Maintenance operations NYPA fleet. Source: Karner, 2005

Ford THiNK was not tested only in this study. For example, UEVAmerica Sheet Baseline Performance Fact tested another Ford Think City´99 in Phoenix, Arizona. This vehicle had the following maintenance operations along more than 12,000 miles traveled:

 Replacement of batteries to 6,319, 10754, 11890 miles, costing approx. $ 200 each time.  The battery service goes down with a swinging load status in 30% to 2,000 km, being replaced within the warranty period.  The radiator fan fault was at 7000 km at a cost of $ 237.  The recharging of the batteries had to be moved inside due to the high temperatures reached outdoor.

The maintenance operations are an additional cost of 800 dollars for the consumer, to which it has to be added the costs that should be borne by the manufacturer during the warranty period. Analyzing the cost of the vehicle in detail, the lease for a period of 30 months costs $

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6381, adding a maintenance cost of $ 837 (0.07 $/mile) and an operating cost (0.56 $/mile), the result of driving an electric vehicle for 30 months is approximately $ 13,590 (1.15 $/mile).

9.3.7. NISSAN HYPERMINI

Between January 2001 and June 2005, the DOE tested eleven Hypermini Nissan models, which accumulated a total of 41,220 miles and 439 months of study in total. The urban electric vehicle attains top speeds of 60mph. On a full charge it has a range of 35-60 miles, but it depends on the weather, conduction and load. The hypermini were equipped with lithium-ion batteries and S-4 Neodymium magnet synchronous AC traction motor (32 hp) powered in rear-wheel.

Since the beginning of the program, some problems with the battery power were found, so it had to act the electrical system which was still in the warranty period. The car incorporated lithium-ion batteries, but it was in the drive system where the greatest number of problems was found, being needed to repair six. Another vehicle was out of service because it was involved in a collision and two of them required the replacement of the auxiliary battery, being several days out of service. Due to the high maintenance requirements, there was an agreement with the local Nissan dealer to supply basic parts and fluids and tire checks, so it decreased downtime.

The next development of the Hypermini is the Nissan Leaf, one of the best selling electric vehicles in 2010.

9.3.8. CANADA

Montreal 2000

Montreal 2000 is a program of tests of different electric vehicles that was implemented in January 1999. A total of 24 vehicles, including Ford Ranger (model with lead-acid batteries and NiMH model), Ford Think (NiCd), Solectria Force (lead-acid batteries and NiMH) and City van (Lead-acid batteries), were tested.

Between January 1999 and March 2001, twenty of the twenty-four vehicles traveled 96,493 km (four vehicles were excluded from the study) whose journeys have a duration comprised

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between 0 and 44 km a day. EV’s availability varies between 77% and 100%, although the average is 88%. The lack of spares in dealerships could take the vehicle out of service for several weeks by a simple maintenance problem. The increase of these times affects to the reliability of the EV, and directly in consumers' confidence in these vehicles. Chart 26 shows all the maintenance carried out during the trial period, to which it must be added the replacement of batteries and the charge in half of the vehicles tested.

Ford Ranger, Solectria Force, Postal van Electric Speed sensor (1) Mechanical Brake line(1) Electric heating (1) Odometer cable (1) Air conditioning regulator (1) Steering rack (1) Fuses (1) Steering system (1) Electric motor (1) Power steering (1) AVCON charging inlet (1) Universal joint (2) Motor oil pump relay (1) Diesel heating (2) Heater element (1) Hand brake (2) ABS controller (2) Main fuse (2) 12 volt batteries (3) Electronic controller (3) Switch box (4) Control panel (4) Traction battery charger (5) Battery controller (11) Work on traction batteries (13)

Chart 26. Maintenance Montreal 2000 Source: Montreal 2000

Almost all the maintenance tasks were entered into the warranty provided by the manufacturers, except for braking system, which had to be repaired once. As these were vehicles to be evaluated, there were not available the necessary spare parts in the repair site, which required an increase in the downtime. This study concluded the great influence that climate undergoes in the vehicle performance; increasing dramatically (up to 30% or 50%) the consumption of the vehicle, either by the consumption of auxiliary systems, such as

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the vehicle’s need. However, EVs are more economical, from an energy standpoint, than conventional transport.

9.3.9. UK

Smart Move Project investigates the introduction of electric vehicles in twelve fleets located throughout the United Kingdom. Mitsubishi iMiEV and Smart ed were studied in five focused organizations: ASDA, Commonwheels, Indesit, Stagecoach, Groundwork, each of them with a different scope. The models were adapted easily to the features required in each company, which supplies much of the mobility requirements.

Figure 105. Smart Move Project vehicle specification Source: Smart Move Project

This study, published in November 2011, was developed between November 2010 and March 2011. Smart Move ICE Project aims to replace EV, where EV efficiency against ICE is higher, varying operating conditions.

This study, published in November 2011, was developed between November 2010 and March 2011. Smart Move ICE Project aims to replace EV, where EV efficiency against ICE is higher, varying operating conditions.

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During the period of the study, low temperatures affected the energy performance of the vehicles to fall, according to the manufacturers, 46% and 36% for iMiEV and Smart ed. In turn, the auxiliary consumption increased to 52% the energy used by the vehicle in the case of Indesit.

The scheduled maintenance of these vehicles on diesel and electric models was assumed by Smart Service Birmingham. In addition, unscheduled maintenance was excluded from the results. Although precise data are not available, Smart Move Project ensures that unscheduled maintenance on electric models is lower than on diesels due to the moving parts. The brake wear will be lower due to the use of regenerative braking.

9.3.10. SWEDEN

In Sweden, from 1996 to 2000, there were various research projects of electric vehicles. For example, in June 1999, there were 591 vehicles on Swedish roads where most representative models were the Renault Clio (35%), Citroen Berlingo (17%) and Renault Express (10%).

Chart 27 shows total failures repaired in the vehicle and the number of them, which brought together along the study. The faults with the vehicle's batteries were the main reason for repair and replacement. The main problem in them was the water-filling on the battery, to be conducted under normal conditions every 4000 km. The second most common failure was due to mechanical problems which include from tire replacement to problems with the brake servo pump.

Type of fault Number of fault Water-filling (traction battery) 149 Others 86 UCL (Vehicle computer) 61 Replacement car 43 Isolation 43 Heater 38 Controller 27 Traction battery 25

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Auxiliary battery 20 Onboard charged 16 DC/DC converter 13 Chassis or crash 12 Lighting 8

Chart 27. Failure rate and type of faults in LEVE. Source: LEVE (2000)

Putting strong emphasis in this study, there were taken as representative 20 samples of the Renault Clio for further study, in which on average it was observed that vehicles visited the shop 3.6 times per year. Considering the average distance travelled by each vehicle, over 4000 km per year, the results show a much more frequent use than in fossil fuel cars. Regarding the average time in garage, it is a mean of 10 days per year, or in the same manner 97% of time available. One conclusion from high maintenance requirements may be due to two reasons, first weather in Sweden and the second one poor development of EVs. Swedish climatic conditions, extremely cold in winter, cause an increase in the consumption of auxiliary elements, such as heating, having an impact on the autonomy of the vehicle, forcing batteries more than their means. A second reason is because these vehicles are poorly developed and they must be studied in order to evaluate their performance and improvements.

Comparing the fault of the vehicles studied during 1997 and 1998, despite the number of faults present in the model Renault Clio Electrique, these problems were reduced compared with the previous year. In models Peugeot 106 Electrique and Renault Express Electrique, the specific deficiencies remained at similar values, but always lower than Renault Clio.

It is also the first generation of electric cars, so cars evolved subsequently will possess higher performance, lower consumption and lower problems / maintenance failures.

9.4. European Projects

9.4.1. PROJECT ELCIDIS

Between March 1998 and July 2002, the European Commission encouraged, within the European 4FP Project, a draft for inserting hybrid trucks and electric vehicles in the

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distribution of supplies in urban areas. The purpose of it is based on demonstrating the feasibility of electric vehicles, the environmental benefits of this type of vehicle and the benefits of an urban distribution system.

ELCIDIS was promoted in six European cities, with a total of 39 vehicles with electric batteries and 16 hybrid vehicles. In Stockholm and Rotterdam it affected the development of electric delivery van with a weight 1000 - 1200 kg. In the French city of La Rochelle, the project focused on the development of a new, clean and efficient distribution system using a 500 kg light vehicle. In the remaining cities, Stavanger, Milan and Erlangen, ELCIDIS focused on the deployment of electric vehicles for in-house goods and mail distribution for companies operating within the urban areas.

Most of the vehicles were tested on private fleets to convince the drivers the reliability and adaptability to urban areas. The acceleration of EV surprised many drivers, higher than expected. Besides, using the EV is an added advantage for health due to the high traffic congestion in many European cities.

Most of the fleet is composed by Renault Partner and Citroen Berlingo, while batteries, predominant use of NiCd batteries with 77%, followed by Zebra batteries and lead-acid only representing 18% and 5% respectively. Although NiCd batteries have a higher performance, European directives about toxicity of the cadmium discourage their use. The high cost of the NiCd batteries represents a 50% of rest of vehicle. On the other hand, the lead-acid batteries, more affordable, do not provide density energy necessary, so the new batteries such as ZEBRA are the ideal ones for use in the future electric vehicles.

On maintenance, electric motor requires much less activity than an internal combustion engine. High electric motor efficiency, along with regenerative braking energy is other benefit compared to internal combustion engines. Low autonomy offered and low speed ranges in the EV are the result of poor batteries development. This disadvantage is a serious problem in the ecological benefit offered by this type of vehicles in world mobility. Some consumers have much higher needs than the ones currently available with these batteries. Such vehicles have little history, so there is a lack of supplies, compared with number of trucks driven by combustion engines. Urban delivery has specific qualities, so that in some cases, current electric supply does not meet the market requirements.

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9.4.2. ZEUS PROJECT

In 1996, it was developed a project in order to implement vehicles of alternative fuels in several European cities located in Greece, Denmark, UK, Italy, Germany and Sweden. The project was divided into several streams testing different fuels, such as vehicles working with natural gas, compressed gas, biogas, biodiesel, hybrid and electric vehicles. Electric fuels used in the project were reduced to only two types: passenger cars and vans, while the heavier vehicles were powered by fossil fuels

The aim was to encourage electric vehicles in the UK. This vehicle is based on the previous experience of the Renault Clio. The models chosen for acclimatization of the English weather were: utilities Fiat 600 Elettra, Peugeot 106 Electrique and a van (Citroen Berlingo Electrique), with a total of 278 vehicles.

The objective was to reduce the prices, putting a price limit for replacement parts, including the maintenance or even imposing penalties in case of delays in the delivery. However, the network of spare parts is not yet sufficiently developed, resulting in many cases long distances from damaged cars for simple repairs. Training of local personnel, capable to repair these technologies, involves extra costs in time and money to offset the reduction in downtime of new vehicles. The experience gained from maintenance personnel considered more complex its maintenance than the one necessary in a combustion engine, significantly more expensive and laborious.

Preventive maintenance measures focused on the most controversial component of the EV battery. Their care included filling of the acid and water, which must be performed approximately every 5000 miles or twice a year, even more often if the vehicles are driven abruptly. Replacing the battery pack, NiCd in this case, should be done every 3-4 years.

Unscheduled maintenance represented major problems. Sometimes there were not available spare parts in repair places, while others are not getting investigate the failure, whether due to the newness fuel or complexity of electronic systems installed. This caused that the vehicles were subjected to long periods out of service.

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9.4.3. EVD-POST ELECTRIC VEHICLE DELIVERIES IN POSTAL SERVICES

The goal of the EVD-POST was to demonstrate the technical and economic viability of EVs in the regular operations of postal services in Europe. It is expected that a successful performance in the particularly demanding stop-start operating cycles of postal deliveries will provide a strong recommendation to other operators for the use of EVs. EVD-POST introduced 59 postal vehicles in several countries (Belgium, Finland, France, Germany and Sweden) between 1998 and 2000.

First 54 models operated with NiCd and lead-acid. They were incorporated at the beginning of the study, while the last 5 vehicles were incorporated in 1999 with a ZEBRA battery. The fleet travelled 930,000 km with an average consumption between 35-60 kWh/100km, 10-25% lower than the diesel or gasoline consumption.

EV easily adapted to the characteristics of the postal route, presenting only an inconvenience about the autonomy in long trips. The maintenance of the fleet was less than in similar vehicles with the same features, except for the Vito model with ZEBRA. The reliability of the vehicle was verified, despite long periods out of service due to lack of spare parts, with the acceptance of unevaluated drivers. The disadvantages of the fleet maintenance appeared in the replacement and repair of some batteries during weeks or even months. The maintenance costs of these vehicles produced an annual expenditure of € 1800, while diesel models cost is only € 400; four times lower than the one for the electric model. EVs require specific parking which a connection to the net and recharge the batteries in the periods of inactivity. This characteristic did not have a good public acceptance.

The efficiency of this fleet is confirmed with good public acceptance, although there are existing barriers that prevent its introduction on the market in the short-term. The reliability has to be improved by developing new batteries. This must be the focal point to be developed in the years following this report.

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9.5. Analysing electric vehicle components

9.5.1. BATTERY

Batteries are the elements that replace the fuel tank of an internal combustion vehicle, but they need more space, are heavier, recharge at a time markedly longer and have less specific energy. As a bonus, it is reversible chemical reactions that occur during a number of cycles, if given the right conditions in the reaction. The number of cycles that can be loaded and unloaded depends largely on the type of battery, state of the battery and, in some cases, on the state of the charge, to have some type of battery called memory effect.

The basic principle of the batteries consists of a negative electrode, called anode, a positive electrode, called cathode, and an electrolyte which produces the flow of electrons. When the electrical circuit is closed, the electrical driving force between the electrodes causes that the electrons flow through the electrolyte. The total battery voltage is determined by the number of cells that make up the battery, by multiplying electrical driving force in each of the cells, with the number of total cells. If connected in parallel, the intensity increases and the voltage remains constant.

The batteries are the limiting factor in the operation of electric vehicles since they are expensive items, heavy and still not a guarantee of autonomy similar to the autonomy of the internal combustion vehicles. The recyclability of different types of batteries is very complicated, so that only these types of batteries are being developed:

 Lead-acid  NiMH  NiCd  Na-NiCl2  Zn-air  Li-ion  Li-Po

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Lead-acid

They are the most commonly used rechargeable batteries in electric vehicles of the 90s. They have a low volume ratio of energy and low specific energy, but on the contrary, its low price made them the most commonly used batteries.

The reaction occurring at the anode is:

Pb(s) + HSO − 4(aq) PbSO4(s) + H+(aq) + 2e−

While at the cathode:

PbO2(s) + HSO − 4(aq) + 3H+(aq) + 2e− PbSO4(s) + 2H2O(l)

The voltage of each cell is approximately 2105 V, with a life cycle of 500-800. Another disadvantage of this type of added battery is that it needs recharging and it often has a high ratio of self-discharge, between 3-20% per month, with performance in loading / unloading ranging in 50-90%.

The model Zytel Gorilla Electric is an example of a vehicle that currently has a lead-acid battery.

NiCd / NiMH

NiCd batteries were present at the first electric vehicles, but the toxicity of the cadmium and its environmental impact, caused them to lose weight in the automotive industry. To replace these batteries, the NiMH batteries were developed, consisting of a NiOOH anode and a cathode of a hydride metal, where the reaction is:

For the anode: H2O + M + e- OH- + MH

For the cathode: Ni(OH)2 + OH- NiO(OH) + H2O + e-

The number of cycles that can withstand this type of battery is higher compared with those of lead-acid, with up to 1000 cycles. The weight of these batteries has been reduced; thereby increasing the specific energy. Despite this, the difference of potential between each cell is 1.2 V. Thus the efficient loading / unloading is 66%.

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It has the disadvantage that it needs to work at a suitable temperature range to prevent overheating and premature failure of the cells, but there is a serious risk of explosion.

Renault Clio Electrique or THiNK Ford 1999 was driven by NiCd batteries, while current models, such as the Ford Think City in 2010, already have NiMH batteries.

Na-NiCl2

These batteries are known by the name Zebra, although its technical name is Na-NiCl2. This is a molten salt battery acting as an electrolyte, where the sodium is present in the negative electrode, while the positive electrode consists of nickel chloride. The elements of these batteries are very common and cheap, because of the availability at the surface, resulting in a very attractive type of battery because it has a long life (3000 cycles), at the same high energy and specific power (90 Wh / kg and 150 W / kg). The reaction that occurs in the electricity generation is:

2 NiOOH + Zn + 2H2O Zn(OH)2 + 2Ni(OH)2

⇒ Several electric vehicles are powered by these batteries such as the Ford THiNK with 224 Ah capacity and a range of 180 km.

Zn-air

Zinc batteries have high specific energy (470 Wh / kg), suitable for places with little space or weight, such as watches, which have a lifecycle of more than 3 continuous years. Zinc is used as fuel by air oxidation as the potential difference occurs in it (1.65 V per cell). Due to this configuration, if the flow of oxygen that enters the cell is not controlled, the discharge is produced.

Li-ion

Lithium is the lightest element with greater electro negativity, resulting in a very interesting element in the construction of energy storage batteries. Currently, lithium-ion batteries are about the most used, and not only in electric vehicles, but also in all types of electronic devices.

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It highlights the high energy density and the specific energy, which make them lighter than other similar batteries. The high discharge capacity has no memory effect and offers a great resistance to self-discharge. The main drawback of these batteries is based on the same high price, the durability of the same (300-1000 cycles) and the temperature range, which if exceeded can cause the battery explosion.

Models like the Mitsubishi iMiEV move through lithium-ion batteries with a range of 150 km or less. Another model is the Citroën C-Zero, with a lithium-ion battery capacity of 50Ah.

Li-Po

The lithium polymer battery is under development and evaluation. It is an evolution of the Li- Ion, so it has very similar characteristics. It has a higher energy density, resulting in weight reduction for the same energy needs. The self discharge rate is lower than the Li-ion battery for longer storing of electric charge and it reduces the energy losses. Furthermore, being an improvement of Li-ion batteries, it has managed to increase the useful life of over a thousand cycles.

Battery’s reliability has promoted its use in various fields such as telephony, electronics, etc., where weight reduction has a beneficial effect.

In October 2010, a prototype electric of an Audi A2, with an energy source of these rechargeable Li-Po, traveled 600 km from Berlin to Munich on a single charge, demonstrating the independence of these vehicles, similar to any other combustion engine.

Lead-acid Nickel-metal Lithium-ion Type of battery Lithium-ion Battery hydride polymer Specific Energy 30-40 30-80 (100) 100-250 130-200 [Wh/kg] Energy Density 60-75 140-300 (385) 250-360 300 [Wh/l] Specific Power 180 250-1000 250-340 7100 [W/kg]

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Charge/Discharge 50-92 66 80-90 99.8 Efficiency [%] Energy Consumer- 7(sld)-18(fld) 2.75 (0.75-1) 2.5 2.8-5 Price [Wh/$] 8 (21ºC) 15 Self-discharge Rate 30 (1-2) 3-20 (40ºC) 31 5 [%/month] Temperature dependent (60ºC) >1000 Cycle Durability 500-800 500-1000 (1500) 400-1200 [cycles] (24-36 months) Nominal cell 2.105 1.2 3.6-3.7 3.7 voltage [V]

Chart 28. Main battery characteristic

9.5.2. LCA (LIFE CYCLE ASSESSMENT)

Rantik (1999) performed a lifecycle analysis on five different types of batteries in electric vehicles (lead-acid, NiCd, NiMH, Na-NiCl 2, Zn-air). In the beginning, some premises were made by the author: that it's a vehicle that weights 1300 kg, to which it will add the weight of each drum kits, that an electric vehicle lengths 200.000 km in 10 years, and that each battery meets the specific conditions of their own. Three scenarios were analyzed: the first, basic with a normal load; the second, combining fast charge with the normal load; and the last one, a stage with only a faster load. The main objective of this study was to analyze what the repercussions throughout the entire product lifecycle would have, from manufacturing of raw materials to recycle components upon completion, through transportation of materials, to complete the cycle.

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Chart 29. Characteristics and number of batteries for the main stage. Source: Rantik (1999)

It was analyzed which one of the five types of batteries was better. For the first scenario, the number of units needed to ensure the entire supply of NiCd batteries cannot be achieved due to the scarcity of cadmium, reach only a production of 300,000 units. In another sense, the four remaining batteries cannot be considered suitable. Lead acid batteries have problems of eutrophication, pollution and carcinogenic potential, NiMH and Na-NiCl2 because of the impact on global warming, and Zn-air due to the acidification potential of the batteries.

The scenarios that provide fast charging provide other different results. Fast charging reduces the life of the battery, increasing the total number of batteries to complete the vehicle's life, seeing dramatically increased the impact of the vehicle. These results may differ when considering the use of recycled materials. If it is only considered the fast charge, the energy consumption is increased, as energy losses.

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Figure 106. Energy used under different load ranges (FU: ten passengers VE year, 200.000km) Source: Rantik (1999)

In Li-ion batteries, the most common faults occurred within the battery module. They can focus on the cells of the battery control module, or in the battery housing. Chart 30 shows the faults collected by Hennig (2010), and the cause, effect and extent of the problem. Certain faults in the batteries can pose a risk to the occupants of the vehicle, for which they have been classified in the Chart 30, where fewer pose a greater risk. For example, the decomposition of the electrode produces a dent in the cell, which has effects of ventilation in the next cell, possibly due to an excessive temperature increase. This failure has a high risk. On the other hand, a break in the bridge of the cells reduces the capacity and increases the resistance of the battery due to a blow easily or vibration and it has less risk than the previous occupants.

Damaging Failure Priority Explanation for Failure mode Cause of failure Effect Critically Operating Boundaries Subsystem/ location for LM Priority component Conditions Battery module Lithium ion cell vehicle Reduced High ambient operation Lithium ion increased negative Degradation of capacity, reduce temperatures, 4 1 with high cell resistance electrode SEI vehicle initial State of SOC- operation range Charge (SOC) changes Reduced Lithium plating Lithium ion increased capacity, reduce Battery low ambient at negative 4 1 cell self discharge vehicle Charging temperature electrode operation range covered by Lithium plating Lithium ion Cell venting, loss Lithium ion Battery high ambient short circuit at negative 1 2 cell of function cell/increased Charging temperatures electrode self discharge

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Reduced Lithium ion increased Decomposition capacity, reduce Battery high ambient 4 1 cell resistance of electrolyte vehicle Charging temperatures operation range covered by Lithium ion Decomposition Cell venting, loss Lithium ion cell Battery high ambient Swelling 1 2 cell of electrolyte of function increased Charging temperatures resistance Reduced Lithium ion conducting capacity, reduce Bad road Design of cell Crack mechanical load 4 1 cell paths vehicle operating mounting operation range Module Control

Board Loss of functionality , Module various reduced Bad road Design of Control Crack mechanical load 4 1 known problem locations capacity, reduce operating fixation Board vehicle operation range Loss of functionality , Module check of loss of reduced real vehicle Control connections oxidation (air) 4 2 connection moisture contact capacity, reduce usage Board design vehicle operation range Reduced Module overheating depositions on to be covered air pollution, capacity, reduce real vehicle Control of electrical board (dirt, 4 1 for air cooled cooling system vehicle usage Board components dust) system design operation range validation Reduced Module overheating relevant failure insufficient capacity, reduce high battery hot ambient Control of electrical 4 1 mode -> cooling situation vehicle usage temperatures Board components depends on operation range customer usage Missfunction, Module coolant leakage reduced not relevant for Bad road Control short circuit (only for liquid capacity, 1 3 air cooled operating Board cooled systems) reduced vehicle system operation range

Damaging Failure Priority Explanation for Failure mode Cause of failure Effect Critically Operating Boundaries Subsystem/ location for LM Priority component Conditions Module Busbar short circuit of battery, Loss of validation Stop-Start functionally, relevant failure Module operation- ageing insulation thermal load reduced 1 1 mode -> Busbar >thermal capacity, depends on cycling load reduced vehicle customer usage operation Loss of functionally, covered by Continuous Module mounting reduced high ambient melting thermal load 1 2 module battery Busbar frames capacity, temperatures busbar/ageing usage reduced vehicle operation High Ohm resistance, loss of interface check of Module reduced real vehicle electric module to corrosion 4 2 connection moisture Busbar capacity, usage contact cell design reduced vehicle operation Module sensors fixation, covered by Temperature loss of Bad road mounting Crack cable mechanical load 3 2 module board/ sensor functionality operating situation connectors crack Battery

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housing Housing

Connection points to battery system Check of real vehicle Housing corrosion vehicle. material pairing misfunction, loss 1 2 material moisture usage Welding of battery pack specification seams Connection moisture; points to battery system customer usage real vehicle geographical Housing corrosion vehicle. salt contact misfunction, loss 1 1 ->seaside usage influence (sea- Welding of battery pack side) seams validation ambient Stop-Start relevant failure temperatures, battery system operation- Housing Crack plastics ageing 2 1 mode -> mounting misfunction >thermal depends on position of cycling load customer usage battery housing check during battery system Bad road Housing Crack stone impact 2 2 functional dirt on roads misfunction operating development

Chart 30. Faults in the batteries and associated risk

9.5.3. MOTOR AC/DC

Electric vehicle replaces the internal combustion engine by an electric motor. The change allows a different configuration of the motor of the vehicle, being able to have a central engine, a single motor located in the center of the vehicle, including a transmission system to the drive axles. The other type of configuration is a driving motor for each wheel, eliminating the transmission system, being the engine directly responsible for transmitting power to the wheel.

When the engine is located in the center of the vehicle, its configuration is different because there is only one engine for the entire vehicle and it is responsible for transmitting power to the drive shaft. This configuration is very similar to the internal combustion engines and to the hybrid vehicles sharing both engines. The transmission has to be composed of more elements, making it more complex.

It can be considered that this type of configuration consists of a conventional electric motor that has been tested during a long period of time, in which reliability and durability has been proven. So there are two types of configurations, the DC motor and the AC motor, which consist of totally different characteristics.

Mitsubishi iMiEV model features a synchronous permanent magnet DC motor, namely Y4F1 model, which drives the rear axle of the vehicle and the drive shaft. The manufacturer mounts Zytek Smart ed models and electric models, a permanent magnet DC motor

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brushless whose powers range is between 55 and 70 kW, equivalent to 70 and 95 hp, and capable of delivering a torque of 120Nm up to over 300Nm.

9.5.4. IN-WHEEL ENGINE

One of the revolutions that take place in the development of electric vehicles is the engine wheel. It is a change in the configuration of the engines, located in the front or rear of the vehicle, delivering to the axles the engine power. This type of engine is an independent supply of power to each drive wheel. It consists of an electric motor located in each one of the drive wheels, and it can be on the front axle, in the rear or both, depending on the characteristics of the vehicle. This configuration provides a balanced weight distribution, extending the useful space and increasing the security measures. This type of engine has a built-in suspension inside the wheel, to withstand the stresses and vibrations, protecting it from bumps and jumps that are not damaged.

In-wheel motor can provide accurate torque and braking force required for each wheel, making it more accurate and safe, eliminating transmission systems or other heavy components. This system integrates turn regenerative braking, recovering the energy dissipated during braking and increasing the efficiency of the vehicle.

Currently, some vehicles have installed this technology, as Ford, on the presentation of the model F-150, a hybrid vehicle with integrated wheel motors on the rear axle, while the front axle was driven by the engine of combustion.

9.5.5. INVERTER

Inverters convert the direct current (DC) drawn from the batteries to alternating current (AC) consumed by the motor. In the case of having regenerative braking system, this system acts in the opposite direction, converting the energy recovered from braking system, to be stored in batteries.

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Inverter’s life cycle has duration of 10 years, 240,000 km or 5000 hours of operation. According to some studies, for example the case of Rantik (1999), whose assumption was 200,000 km travelled, it appears that the investor takes over the life of the vehicle, so it is not necessary to replace, or make specific maintenance operations. Actual tests on various global fleet have determined that during the testing process they have not been affected in this type of problem.

9.5.6. POWER CONVERTER

Power converter is an electronic device that converts the current from a voltage to another to achieve energy conservation and minimize power loss. The situation should be monitored at every moment of the vehicle, whether it is a braking or during the acceleration process in the forward or backward motion. The combination of both requires different conditions of current or voltage from the motor to the batteries, and vice versa.

Figure 107. Operating diagram power converter DC/DC. Source: Santos (2007)

Studies made by Wehrey (2001), or projects such as Montreal 2000, and LEVE (2000), show problems in the power converters installed in some vehicles. These problems represent 2.4% of all shortcomings of the LEVE project, in the case of Montreal 2000 project, this figure represents 3.6% of electrical faults in the 24 vehicles studied for a period exceeding two years. The case of Wehrey studied for DOE (Department of Energy), shows a higher percentage, 5.4% although this may not be representative only two vehicles in accounting for heavy maintenance, so cannot be extrapolated to the rest of the fleet.

9.6. Conclusion and guidelines

Reliability of electric vehicles is called in question because the test programs are not able to demonstrate their objectives. This lack of trust has a serious impact on the market that

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makes the customer lose confidence to the new challenge and its development involves the introduction of this new type of mobility. The offered warranty costs are inversely related to the product reliability. Increasing reliability, it increases the useful life and therefore it is reduced the risk of warranty deterioration.

Currently there are still many test scenarios that have not been tested or are being tested, of which no definitive results are known. At the same time, new innovative components, which are an improvement, do not have enough data to ensure reliability and improve the performance of previous systems.

The most problematic component of the electric vehicle is, no doubt, the battery, while being the most expensive and heavy for all that make the electric vehicle. A challenge is to ensure the safety and durability of it, thus it will provide a pleasant reliability. It represents in many studies the high percentage of the total error (see Project LEVE case, where it accounts for 27.54%).

Other reasons for failure in the fleets studied are due to insulation failures (8%, LEVE project). The high voltage supplied to the engine produces excessive wear and they become a problem with serious risks to the occupants of the vehicle.

Common elements between the different types of vehicles do not have a different wear that the one they have when they are subjected to combustion in vehicles, so there is no need to be changed. For example, the tire wear is not influenced, with the exception of in-wheel motor, which results have not been yet studied.

9.7. References

[1] IEA. June 2011. Technology Roadmaps Electric and plug-in hybrid electric vehicles (EV/PHEV) [2] Idaho National Laboratory, June 2000. Field Operations Program: Toyota RAV4 (NiMH) Fleet Evaluation Final Report [3] M. Wehrey, J. Argueta, F. Sanchez, J. Phung. December 2001. Demonstration and Evalua-tion of U.S. Postal Service Electric Carrier Route Vehicles [4] Ryerson, Master and Associates, Inc. 2003. United States Postal Service, Electric carrier route vehicle program: 500 vehicle fleet deployment report

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[5] P.T. Jones 2010. Dynamometer Testing of USPS EV Conversions. U.S. DOE Hydrogen Pro-gram and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting May 11, 2011 [6] J. E. Francfort, R. R. Bassett, S. Briasco, W. Culliton, E. F. Duffy, R. A. Emmert, J. R. Hague, R. Hobbs, B. Graziano, I. J. Kakwan, S. Neal, L. Stefanakos, T. G. Ware. 1998. Site Operator Program Final Report. [7] M. Dubarry, M. Bonnet, B. Dailliez, A. Teeters, B. Y. Liaw. 2005. Analysis of Electric Vehicle Usage of a Hyundai Santa Fe Fleet in Hawaii. Journal of Asian Electric Vehicles, vol. 3, No. 1, 657-663, 2005 [8] Ford Company. 2005. TH!NK city Electric vehicle demonstration. Final project Report [9] D. Karner, J. Francfort. 2005. NYPA/TH!NK Clean Commute Program Final Report - Incep-tion through December 2004 [10] UEVAmerica Advanced Vehicle Testing Activities: 1999 Ford TH!NK city [11] R. Brayer, J. Francfort. 2006. Nissan Hypermini Urban Electric Vehicle Testing [12] R. Brayer, D. Karner, K. Morrow, J. Francfort. 2006. Guidelines for the Establishment of a Model Neighborhood Electric Vehicle (NEV) Fleet [13] Ceveq. 2000. Montreal 2000 – Electric vehicle project [14] S. Carroll. 2011. The Smart move Case Studies [15] N. Fridstrand. 2000. A database on Electric Vehicle Use in Sweden. Final report KFB- Rapport 2000:22 [16] J. Ericson. 2005. ZEUS international procurement of electric vehicles (Greece, Denmark, UK, Italy, Sweden) [17] p. Van den Bossche. EVD-POSTElectric Vehicle Deliveries in Postal Services [18] M. Rantik, CTH. 1999. Life cycle assessment of five batteries for electric vehicles under different charging regimes [19] R. Santos, F. Pais, C. Ferreira, H. Ribeiro, P. Matos. 2007. Electric Vehicle - Design and Implementation Strategies for the Power Train. International Conference on Renewable ener- gies and Power Quality. Sevilla 28, 29 and 30 March 2007 [20] V. Hennige, AVL list (Austria). 2010. Testing of Robustness, Reliability and Safety of Bat-tery Packs. Joint EC / EPoSS / ERTRAC Expert Workshop 2010 “Electric Vehicle Batteries Made in Europe” European Commission, Brussels 30 November 2010 [21] V. Hennige, AVL list (Austria). 2010. Testing of Robustness, Reliability and Safety of Bat-tery Packs. Joint EC / EPoSS / ERTRAC Expert Workshop 2010 “Electric Vehicle Batteries Made in Europe” European Commission, Brussels 30 November 2010

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[22] J. Lutz. 2003. Electric Vehicle Inverters. The DOE Workshop on Systems Driven Approach to Inverter R&D. Maritime Institute, Baltimore, MD April 23-24, 2003 [23] Catalogue Mitsubishi iMiEV [24] www.zytekautomotive.co.uk/Home.aspx

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ABBREVIATIONS

BEV: Battery Electric Vehicle

BMS: Battery Management System

CHAdeMO: CHArge de MOve, "charge for moving", "O cha demo ikaga desuka", "Let's have a tea while charging"

DOD: Depth of discharge

ELTV: Electric Light Truck and Van

EV: Electric Vehicle

FEV: Fully Electric Vehicle

HEV: Hybrid Electric Vehicle

ICE: Internal Combustion Engine

IEA: International Energy Agency

NEV: Neighbourhood Electric Vehicle

PHEV: Plug-in Hybrid Electric Vehicle

PMSM: Permanent Magnet Synchronous Motor

PTC Thermistor: Positive Temperature Coefficient Thermistor

SoC: State of charge

USABC: United States Advanced Battery Consortium

US-DOE: United States Department of Energy

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