Technical manual Nilar Energy Storage Advanced NiMH battery technology The ultimate sustainable energy storage solution. One that is more efficient, safer and has a much smaller environmental footprint than any other solution in its class. Smart Grid solutions

A

E

B D

C

A. Renewable energy storage – Zero emission, D. Re-conceptualising shopping malls – Energy micro grid solution for industrial application conservation for a greener shopping environment

B. Smart energy storage for smart offices – E. EnergyHub – Intelligent energy management Interconnected energy management system of with effective storage with bi-polar technology

C. Hybrid Canal Boat – Clean and silent propulsion for the inland waterways 3

Contents

Nilar batteries and energy storages ...... 4 The Nilar battery energy storage system. . . 22

Solutions and applications ...... 5 Features ...... 23

The 12 V, 10Ah Energy Module...... 6 Nilar battery energy storage systems . . . . . 24 System overview...... 24 Nilar battery pack features ...... 7 Nilar Battery Management System (BMS) . . . 25

Operating features...... 8 Configuration ...... 26 Discharging...... 8 Charging ...... 10 Installation...... 27 Self discharge ...... 11 Cycle life...... 11 Nilar system components...... 28 Battery packs ...... 28 Transport ...... 12 Monitoring unit ...... 28 Programmable logical controller (PLC) . . . . 29 Recycling...... 13 Circuit breaker ...... 29 Fuse ...... 29 Safety...... 14 Current sensor ...... 29

Design ...... 16 Notes ...... 30 Pack design ...... 17 Modular design ...... 18

Electrochemistry ...... 20 4

Nilar batteries and energy storages

Nilar provides customers with high voltage industrial energy storage and battery solutions that are safer and environmentally friendly. Solutions are built on modular and flexible battery packs based on the Nilar battery energy module and integrated battery management systems for high voltage systems. 5

Solutions and applications

Enormous infrastructure investments are required to upgrade the grid if it’s going to cope with the long-term demands of the fast emerging market and the rise in distributed energy use from intermittent sources, such as wind and solar power.

Postponing upgrades with smart energy storage solutions is the only way forward for many governments and energy providers. But this should not be considered a short-term solution. With the right system, energy storage can act as an effective buffer for many years to come and be equally effective if and when grid upgrades are carried out.

Home/Business storage Energy market – Time shifting

EV-charge support Power market – Peak shaving

Industrial support Power market – Peak shaving

Features: Advanced energy storage:

• Decrease your power tariffs • Small scale storage • Increase your share of renewable energy • Commercial & Industrial storage • Relieve stress on the grid • EV-charging • Use a solution that is sustainable from cradle to grave • Utility storage • Safer energy storage • Uninterruptible Power Supply (UPS) • Clean Energy Supply 6

The 12 V, 10Ah Energy Module

The 12 V Energy Module is the building block in Nilar’s • The patented Nilar bi-polar design enables Nilar to energy storage and battery solutions. The module is a offer safer, reliable and cost efficient energy storage maintenance-free, energy-optimised battery with high solutions. power capability designed for demanding professional applications. The high energy throughput, long cycle • High energy density with excellent discharge power life, wide operational window and excellent safety and capability over a wide temperature range. environmental characteristics of the nickel-metal hydride technology makes it possible to supply power to a large • The Nilar battery requires very low maintenance, in many number of applications. cases no maintenance, and is a sealed design with no emissions of gases or during its service life.

• The Nilar battery is easy to transport and is not affected by any costly or complicated transport regulations.

• The Nilar battery contains none of the regulated heavy metals mercury, cadmium and lead. The design has been developed to enable a cost efficient recycling process and a high degree of reused materials. 7

Nilar battery pack features

Nominal voltage Storage The cell voltage of a battery cell is governed by the Nilar battery packs can be stored several years without electrochemical potentials of the active materials used in loss of performance. the negative and positive and the electrolyte. For the nickel-metal hydride system used in Nilar battery Maintenance packs, the nominal cell voltage is 1.2 V. Modules in a pack Nilar battery packs use a sealed design that requires and packs are connected in series to achieve a nominal a minimum of maintenance, for many applications no battery voltage between 60 – 600 V in multiples of 12 V. maintenance at all is required.

Rated capacity The battery capacity is rated in ampere-hours (Ah) and denotes the quantity of electricity a fully charged battery can deliver at a 5 h discharge to 1 V per cell at +20 °C. Modules have a capacity rating of 10 Ah. Modules in a pack and packs are connected in parallel to achieve rated battery capacity in multiples of 10 Ah.

Operating voltage Typical cell operational voltage is 1.6 V during charge to 1 V per cell at discharge corresponding to 16 to 10 V for a 12 V module.

Operating temperatures The batteries can be operated in temperatures from -20 °C to +50 °C.

Intermediate state of charge Batteries can be stored or operated at an intermediate state of charge without loss of performance.

Installation The design is a sealed design. At normal operating conditions Nilar battery packs do not produce any emissions and require no forced ventilation to remove flammable gases generated during operation of the battery.

Reliability The Nilar battery is a stable electrochemical system regarding structural integrity of its components. There is no corrosion of components resulting in premature and unpredictable critical damage to the battery or any type of sudden death. The design is shock and vibration resistant. The end-of-life characteristics of Nilar battery packs display a graceful decline in performance over the life of packs. 8

Operating features

Discharging 15 0.2C 14 0.5C Discharge performance 1C 13 After a moderate initial voltage drop the discharge 2C voltage is stable over more than 80 % of the discharge 12 3C and ends with a distinct knee at end of the useful 11 Voltage [V] Voltage capacity. Discharge voltage is dependent on discharge 10 rate, temperature and the state of charge. The discharge 9 voltage decreases with increased discharge rates and decreasing temperature. The discharge performance is 8 affected moderately at elevated temperatures but at low 0% 20% 40% 60% 80% 100% Capacity temperatures the effect of temperature on discharge performance is more pronounced, mainly due to the Figure 1. increase in resistance at low temperatures. The discharge Typical voltage profiles for constant current discharges with capacity, or the run-time to end of discharge, is mainly various discharge rates. Charging and discharging made at +20 °C. affected by discharge rate and temperature. Delivered capacity depends on the selected discharge cutoff voltage and decreases with increasing discharge cutoff voltage.

15 40 °C Test currents in this manual are expressed as multiples 20 °C of the rated capacity value denoted by C. E.g. a discharge 14 0 °C current of 2C for a Nilar battery pack with a rated capacity 13 -20 °C of 10 Ah equals 20 A. 12

11 Voltage [V] Voltage 10

9

8 0% 20% 40% 60% 80% 100% Capacity

Figure 2. Constant current discharge with 0.2C at various temperatures. The battery was fully charged at +20 °C, acclimatized for 12 h at test temperature and then discharged. 9

100% 1V/Cell 120%

1.05V/Cell 100% 80% 1.1V/Cell 80% 60% 60%

Capacity 40% Capacity 40%

20% 20%

0% 0% 0 1 2 3 -30 -20 -10 0 10 20 30 40 50 Discharge rate (C-rate) Temperature (°C)

Figure 3. Figure 4. Available constant current discharge capacity for various Constant current discharge capacity at various temperatures. discharge cutoff voltages. Constant current discharge with The battery was fully charged at +20 °C, acclimatized at test 0.2C at +20 °C. temperature for 12 h and then discharged with 0.2C to 1 V per cell at test temperature.

20 40 °C Discharge cutoff voltage 20 °C Recommended minimum discharge cutoff voltage is 1.1 0 °C to 1 V per cell depending on discharge rate, battery size 15 and environmental conditions. Lower cutoff voltage can be used at low temperatures and high discharge rates 10 for better utilization of the capacity. Discharge to low

voltage may result in deep discharge, or in extreme cases 5

reversed polarity, of one or several cells in the battery (mΩ/Cell) Cell resistance before the entire battery reaches the pre-set discharge 0 cutoff voltage. Deep discharging, and especially reversed 100% 80% 60% 40% 20% polarity, will have a detrimental effect on the performance. State of charge Pack voltage and module voltages are available for monitoring by the 15-pin signal connector. Figure 5. Cell resistance at various temperatures and charge levels. 30 s pulse duration and a discharge pulse current of 3C. Discharge resistance The resistance varies with temperature and state of charge. At +20 °C the optimum resistance is achieved at 80 to 30 % state of charge. Below 20 % state of charge the resistance increases significantly. The resistance increases with decreasing temperature. 10

Charging

Nilar charging systems Recommended charge procedure Nilar battery packs require optimized charge procedures The recommended charge procedure is constant and charge settings to ensure performance and service current charge with charge termination based on life. Constant current chargers modified to enable control rate of temperature increase (dT/dt) together with a from the Nilar charging system are required. Packs with maximum allowed pressure and pack temperature. The modules connected in series, with a rated pack capacity recommended charge rate is 0.3C to dT/dt corresponding of 10 Ah, can be charged with constant current chargers to 0.3 °C in 2 minutes. The charge procedure can be used with specific charge termination settings that are based for charging battery packs with battery pack temperature on pack temperature, pressure and terminal voltage. In in the range of -20 °C to +50 °C. Maximum allowed parallel configurations packs have to be charged with pressure is 586 kPa corresponding to 85 PSI. Charging electronic charge control systems controlling individual shall be terminated when the battery pack temperature modules in the pack. The electronic charge systems reach +58 °C. A deep discharged battery pack is recharged offered by Nilar can be used with both serial and parallel in less than 3.5 h. pack configurations. An inherent feature of the NiMH electrochemical system Charging with chargers and charge settings not approved at constant current charging is the build-up of pressure by Nilar will void warranties and may damage the battery. and temperature at the end of the charge. It is therefore important to use a correct charge method to ensure For specific applications, where the customer wants sufficient performance. At low temperatures the charge to integrate their own battery management systems, rate can be limited by an increased voltage needed Nilar will provide algorithms and settings in cooperation to charge the battery. At elevated temperatures the with the customer. The following specified charge maximum charge rate is limited by the rise in temperature procedures and settings are presented as general charge and pressure at end of charge. recommendations. If the electronic charging systems developed by Nilar are not to be used please contact For a battery in service the cells in the battery will with Nilar for detailed information on charge procedures and time reach various charge levels due to temperature settings. gradients in the battery causing small variations in self discharge rate and impedance. The result is reduced High voltage Battery Management System (BMS) run-time and, in extreme cases, accelerated ageing of the • High voltage system 60 – 600 V battery due to deep discharge of the low capacity cells in • Communication interface with charge settings, alarm the battery. Balancing of cells in Nilar battery packs can signals and pack status indicators for large format be achieved simply by a limited overcharge allowing the energy storage systems low capacity cells to become fully charged. Heat generated • Communicates with main control system through at overcharge is detrimental to the performance and have Programmable Logic Controller (PLC) to be considered in the charge design. Cell balancing is included in the electronic charge solutions provided by Nilar. 11

Cycle life

Typical terminal voltage, pressure and temperature when Cycle life is the number of charges and discharges a charging a 12 V / 10 Ah Nilar battery pack at +20 °C with a battery can achieve before the discharge capacity drops constant current charge rate of 0.2C is shown in Figure 6. to a predetermined capacity. Cycle life is affected by temperature, charge method, charge and discharge rates and the depth of discharge. The depth of discharge has a

16 50 large impact on the cycle life. The less deeply a battery is cycled the greater the number of cycles is achieved until 15 40 the battery is unable to sustain the required minimum design limit. Nilar battery packs can achieve cycle life in the 14 30 range of several thousand cycles at intermediate depth of 13 discharge and two thousand cycles at deep discharge. 20 Voltage [V] Voltage 12

10 11 Temperature (°C), Pressure (PSI) (°C), Pressure Temperature 10 0 0 1 2 3 4 5 6 Time (h)

Voltage Temperature Pressure

Figure 6. Typical charge characteristics at +20 °C. Constant current charging with 0.2C.

Self discharge 100%

The state of charge of a Nilar battery pack during storage 80% slowly decreases with time due to self discharge. The self discharge is caused by internal electrochemical reactions that slowly discharge the battery. The self discharge rate 60% is high the first days of storage but then levels out to a few percent per month depending on temperature. The rate of self discharge is increased at elevated temperatures 40%

and decreases at low temperatures. A fully charged Nilar [Ah] capacity Retained battery pack, on storage at +20 °C, will lose about 6 % capacity after one day and 13 % capacity after 28 days. 20% Parasitic loads on the battery from charger, load and electronic systems will increase the rate of capacity loss 0% during storage. 0 6 12 18 24 30 Time (month)

0°C +20°C +40°C 60°C

Figure 7. Self discharge when charged to 75% SOC. Typical charge retention at +20 , +40 and 0 °C at various storage periods. 12

Transport

One of the advantages with Nilar battery packs, as In the case of transport in equipment, the battery must be compared with many other battery types and especially disconnected and exposed terminals must be protected Li batteries, is that UN approved packaging and from short-circuits. marking is not required for transport by sea, road, rail and air. Please observe that special regulations apply for defective or damaged batteries that have the potential of leading to No dangerous goods documentation is required when a hazardous event during transportation. Please contact transporting Nilar battery packs by road or rail. local expertise or Nilar for advice regarding transport of damaged or defective batteries. A dangerous goods declaration is required if batteries are transported by sea in quantities of over 100 kg in one transport unit. Nilar battery packs are then defined as dangerous goods, class 9. UN number and Proper Shipping Name are UN 3496 and Batteries, Nickel-Metal Hydride respectively.

An Air Waybill or similar is required if batteries are transported by air. Nilar battery packs are not classified as dangerous goods and belong to the entry “Batteries, dry” in the list of dangerous goods in IATA (no UN number). If an Air Waybill is used, the words ”Not Restricted” and the Special Provision number (A123) must be included in the description of the substance on the Air Waybill, according to IATA-DGR.

The safety precaution that all battery types, including Terminal cover Nilar battery packs, must fulfill in transportation is that the batteries must be separated from each other to prevent short-circuits and be securely packed to prevent movement that could lead to short-circuits. Terminals should be effectively insulated. 13

Recycling

Environmental protection is highly prioritized by Nilar, starting at the design and development of new products, during production and process development, to end-of- life collection, disposal, and recycling. Nilar continuously works to improve all stages of the battery’s life cycle with the aim to minimize environmental impact. Nilar stays in the front line of recycling technology by participating in different research programs for recycling. The pack design is optimized for a high level of recycling of the materials and to enable cost efficient recycling processes.

In Europe handling of battery waste is regulated according to Battery directive 2006/66/EC and EU Member state national legislation. Nilar takes full responsibility for taking back our batteries and for the recycling process of our batteries. Returned batteries are systematically recycled and the materials are re-used either in new batteries or in other industries.

When your Nilar battery is ready for disposal it is recommended to send the battery to the local Nilar battery dealer or to Nilar AB.

The battery must be protected from short-circuiting during transport. Please see section regarding transport.

Never incinerate or dispose of Nilar battery packs as landfill. 14

Safety

Nickel metal hydride batteries is a mature technology that • Short circuit - To prevent short circuit, Nilar has has been used commercially for over 25 years for a variety installed fuses on both the positive and negative side of of applications including consumer products, electric each string. At full short circuit, the Nilar batteries start vehicles, hybrid electric vehicles, and stationary power to ventilate oxygen/hydrogen gas after 60 seconds of applications. The introduction of batteries into cars are abuse. now driving the safety regulations both for vehicles and • External heat/fire - If an external fire would occur near other battery applications, such as energy storage. the battery bank, the fire should be extinguished by water, in the same way as a corresponding electronics The main safety benefits of Nilar NiMH batteries are: fire. If the fire is not extinguished, the heat will • Water-based electrolyte(1) - battery pack do not impose a eventually cause the Nilar batteries to ventilate oxygen/ risk of exploding if anything unforeseen happens. hydrogen gas. This scenario should be addressed in the • An ”Anti-propagation test”(2) is not applicable, since same way as a corresponding fire in a lead-acid battery thermal runaway is not an issue for the Nilar advanced installation. NiMH chemistry. • and are non-flammable in the Nilar technology. • NiMH does not form dendrites, which in the long term can cause short circuits in the cells. This means that there is no limitation to the number of cycles based on remaining capacity. For the same reason, the Nilar batteries can also be charged in temperatures below 0°C.

One of the many functionalities of the Nilar Battery Management System (BMS) is the prevention of the battery from being overcharged or deep-discharged(3).

In the event of: • Overcharging - The Nilar battery can manage an overcharge with 0.2C for 5 hours, or 1C for 30 minutes, without ventilating oxygen/hydrogen gases. If not interrupting the charging, the battery will ventilate oxygen/hydrogen gases and the internal temperature will increase. If the charge is terminated, the process will stop. This means that Nilar NiMH batteries can not enter a thermal runaway.

(1) NiMH batteries have an aqueous electrolyte that is not flammable compared to the highly flammable organic electrolyte used in lithium ion batteries. If the organic electrolyte is catching fire, explosive and poisonous gases are released.

(2) Propagation is a dangerous phenomenon that can occur in lithium ion batteries where one cell that has run into thermal runaway can spread the heat to other cells and in that way initiate thermal runaway in other cells, so it becomes a cascade effect.

(3) All lithium ion batteries require a very strict safety region when it comes to upper voltage limits, temperature limits and current limits. If you pass the set limits, then you come into the safety critical region where thermal runaway can be triggered by internal short circuits and/ or external heat. For example, during deep discharge or overcharge. 15

Nilar batteries are also certified for transport via road, rail, sea or air, without the need for heavy and expensive explosion-proof containers. 16

Design

The bi-polar design enables Nilar to produce modular uniform heat gradients over the electrodes. A uniform batteries with improved volumetric power density and battery temperature promotes a uniform electrochemical simplified battery construction. The modular concept aging of the electrodes in the modules, which translates makes it easy to match packs to different design into a long service life. requirements and to refit existing batteries to new demands in run-time or power. The main advantage of the bi-polar design utilized by Nilar is the common and shared large area current collector. This important feature reduces the volumetric overhead of the current collectors and inherently results in uniform current flow across the cell. Uniform current and resistance paths promote

Module Contact plate Pressure sensor

End-piece Isolation sheet Positive terminal plate Negative terminal plate

Safety valve 15-pin signal connector 17

Design

Pack design

The pack design achieves a compact assembly of cells Contact plate and other components required in a battery pack to The contact plate electrically connects the adjacent meet required system voltage and run-time. A typical modules in the pack and thus eliminates the need for pack consists of 12 different types of components, external connectors between modules. The design of assembled to a pack by a pick and place manufacturing the contact plate allows for efficient active air cooling in process, followed by electrolyte filling and formation by demanding high power applications. a few cycles of charging and discharging to activate the electrochemical system in the cells. Module Modules with a rated capacity of 10 Ah are the building End-piece blocks for all Nilar battery packs. There is one end-piece on each side of the pack connected with tie-rods to assure the required cell compression. 15-pin signal connector Besides providing uniform cell compression over the Connector for monitoring analog signals for pack and surfaces they also provide impact protection to module voltages, pack pressure (common for all cells in the modules. the pack) and pack temperature.

Safety valve Nilar battery packs are fitted with one pressure valve per pack with an opening pressure of 689 kPa corresponding to 100 psi. The pressure valve is located on the end-piece with the positive terminal pillar marking. The pressure valve is only activated at abusive conditions.

Isolation sheet The isolation sheet insulates the end-pieces from the pack voltage potential.

Terminal plate The terminal plate is a contact plate with an integrated terminal pillar for connecting power cables to the pack. There is one positive and one negative terminal plate per pack. The terminal connector design of Nilar battery packs does not require any means of sealing between terminal and container to maintain the integrity of the electrochemical system within the cells. The design eliminates the risk of electrolyte or gas leakage through any terminal sealing. 18

Modular design

The modules are the building blocks of all packs offered by Nilar. The modules are manufactured in a fully automated pick and place manufacturing process with binders and volatile organic solvents eliminated in the process. The high quality of the modules is an inherent feature of the patented Nilar bi-polar design and the state-of-the-art manufacturing process.

Biplate Gasket Cell Case Contact plate Module

EPDM bushing Electrodes 19

Electrodes Gasket The positive and negative electrodes are manufactured Each cell is surrounded by a gasket. The gasket together by a patented method for compression of dry powders with the biplates provide a seal between the interior of the without any expensive plate support material, binders or cell and the exterior. The hydrophobic properties of the volatile organic solvents. Active materials and additives, gasket prevent the creation of electrolyte bridges between as dry powders, are mixed with each other before being adjacent cells. Each gasket is provided with an opening to compressed in a calendar system to form continuous enable electrolyte filling. sheets of compressed electrode material. The sheets of active materials are cut into electrode plates. Case The electrode manufacturing process yields very low The case provides impact protection to the cells in the deviations in electrode plate dimensions, weight and module and prevents the gaskets from being deformed by capacity and are one of the main contributions to the the cell pressure. The case is made of injection molded high quality of Nilar battery packs. polyamide. Openings are provided in the case for the tie rods connecting the end-pieces. Separator The separator prevents electrical contact between the positive and negative electrodes in the cell while holding the electrolyte necessary for ionic transport. The separator consists of a non-woven, melt-blown, acrylic acid-grated polyolefin.

Electrolyte The electrolyte is a solution of potassium hydroxide and lithium hydroxide. The design is a so called starved electrolyte design with no free volume of electrolyte in the cells. All of the electrolyte volume is absorbed by the positive and negative electrodes and in the separator. The electrolyte will maintain its function over the service life of the battery and does not need to be replaced or adjusted.

Biplate The biplates, together with the gaskets, are the means for sealing each cell. The biplates also provide electrical contact between cells. The biplates are made of thin nickel foil. Each biplate is provided with an opening to enable electrolyte filling. 20

Electrochemistry

Discharge Charger or load ( + ) ( - ) e-

e- Charge M M M Ni OH OH- OH H H

M M M Ni OH OH H H H H

M M M OH Ni OH H H M M M H2O

Negative electrode Electrolyte Positive electrode

Figure 12. Electrochemical principle. 21

Electrochemistry

The Nilar battery would commonly be referred to as a rechargeable nickel metal hydride (NiMH) battery. We also refer to it as a hydrogen or H-battery, due to its close overall similarity to Li-batteries. In H- and Li-batteries, hydrogen or lithium atoms, respectively, move between the electrodes when the cells are charged and discharged. In a charged H-battery, hydrogen atoms are stored in a metal alloy constituting the anode. When the cells are discharged these hydrogen atoms are transferred to the cathode via the electrolyte in the form of water molecules. The chemical energy is essentially contained in an oxygen hydrogen bond.

One major difference between the chemistries is the possibility to include a chemically based overcharge and overdischarge protection in the H-battery. This is a consequence of a water based electrolyte and that hydrogen can form gaseous hydrogen molecules and be transported in the gas space between the electrodes. When the H-battery is overcharged oxygen gas will form at the positive electrode by splitting water molecules at the cathode. In Nilar’s design, this oxygen gas can pass through the separator and be recombined again to water at the anode electrode. Thus, no net reaction takes place, but the energy input will result in increased temperature and pressure. These can be monitored and used to terminate charging. Similarly, during overdischarge hydrogen gas will evolve at the cathode but again it can be recombined to water at the anode – again resulting in heat generation and a pressure increase but no net reaction. In extreme cases of overcharge and overdischarge the recombination reaction will not be able to reduce the pressure and the safety valve will open to reduce pressure and avoid cell rupture. The cell voltage allows for a water- based electrolyte to be used. The Grotthus hydrogen hopping mechanism between water molecules in water, gives water-based superior conductivity. This adds to safety as the electrodes can be kept well separated by robust separators. 22

The Nilar battery energy storage system

Nilar offers high power battery solutions that are robust, resource efficient and have a low lifetime cost. The energy storage systems from Nilar are optimised for industrial use with a nominal system voltage from 60 V up to 600 V. 23

Features

• Service life • Reliability High voltage solutions achieve 2,000 cycles with the Nilar The Nilar nickel metal hydride bi-polar battery design battery management system. is a stable system regarding structural integrity of its components. There is no corrosion of components • Fast charge resulting in premature and unpredictable critical damage 50 % of rated capacity can be recharged in 10 minutes. to the battery or any type of sudden death. The design is shock and vibration resistant. Nilar battery packs display a • Distributed system gradual and predictable decline in performance over life. Nilar high voltage solutions can be distributed for optimum utilisation of available installation space. • Maintenance Nilar battery packs use a sealed design that requires a • System voltage minimum of maintenance, and for many applications no Nilar solutions fit high voltage electronics excellently. maintenance at all is required. Nominal voltages range from 60 V up to 600 V with an operating voltage window between 10 % below and 25 % above nominal voltage.

• Intermediate state of charge Batteries can be operated and stored at intermediate state of charge. Batteries can be cycled at intermediate state of charge with fast charge capability enabling short recharges when possible.

Advanced energy storage:

• Small scale storage • Commercial & Industrial storage • EV-charging • Utility storage • Uninterruptible Power Supply (UPS) • Clean Energy Supply 24

Nilar battery energy storage systems System overview

Nilar energy storage systems are optimised for industrial use, with a common voltage bus on which the battery will charge and discharge. Nilar Battery Management System (BMS) is based on Nilar battery management software and a data monitoring unit fitted on the packs. The battery management software is downloaded to an industrial programmable logic controller (PLC) that controls the battery by communicating with higher level systems. The MU BMS communication and control functions of the PLC manage the battery within the operating limits to meet the MU designed service life in a specific application. The large PLC amount of data measured and monitored at high frequency on pack level is processed by the BMS. Only system critical battery data is communicated to higher level systems and/ HMI MU or to a human-machine interface (HMI) for battery status information purposes.

Through the PLC, the BMS controls circuit breakers located on the positive and negative sides of each string in the battery. On command from a higher level system, or if any critical abnormal condition is detected in the battery by the BMS, a single string or the entire battery can be disconnected from the common voltage bus. Current into Battery pack with monitoring unit and out of a string in the battery is monitored by a current sensor on each string. Up to 36 packs can be connected to one PLC. The number of strings connected in parallel Figure 1. Typical energy storage system to the common voltage bus is not limited by the Nilar structure with one string of battery packs. high voltage energy storage system. Battery packs can be distributed to optimise utilisation of available space for the battery installation.

The main components of Nilar energy storage systems are:

• Nilar Battery Management System (BMS) • Nilar battery packs with monitoring units • Current sensors • Programmable logical controller • Circuit breakers • Fuses

Figure 2. Example of the Nilar Human Machine Interface (HMI) with a configuration of 7 battery strings. 25

Nilar Battery Management System

Nilar BMS is based on specific characteristics of Nilar battery packs and is developed to optimise utilisation of installed battery capacity and service life. The BMS will issue warnings or alarms to higher level systems when battery conditions are out of range. If critical conditions are detected in a string, the BMS will disconnect the string. The settings are optimised by Nilar depending on the system and application.

Condition Default limit BMS signal BMS action Pack warm 40°C Warning No active action Pack overheat 55°C Alarm Disconnect string Pack pressure high 60 PSI Warning No active action Pack over pressure 75 PSI Alarm Disconnect string Pack pressure rise ±10 PSI/min Alarm Disconnect string Pack pressure drop -10 PSI/10 s Alarm Disconnect string Pack temperature low -10°C Warning No active action Low voltage 11.5 V / module (10 cells) Warning No active action High voltage 15.5 V / module (10 cells) Warning No active action Low voltage 11 V / module (10 cells) Alarm Disconnect string High voltage 16 V / module (10 cells) Alarm Disconnect string Low state of charge 25 % Warning No active action Low state of charge 20 % Warning Disconnect string Low state of health 60 % Warning No active action High ambient temperature 40°C Warning No active action Low ambient temperature -10°C Warning No active action

Through the PLC, Nilar BMS will issue commands to 10 minutes fast charge corresponds to 50 % of the rated higher level systems to regulate charging. Charging battery capacity, providing sufficient power is available. is based on constant current charging with charge Fast charging is enabled from 20 % state of charge and is termination dependent on individual pack conditions. terminated when 80 % state of charge is reached. Charging to full capacity is performed with currents from 2 to 3 A per string. FullLo wrecharge from deep discharge is performed in less than 3.5 hours.Application/HMI Fast charge

The battery can be cycled at an intermediate state SOC [%] 02080 100 of charge, with fast charge capability enabling short Circuit Breaker rechargesInformation where possible. Nilar high voltage BMS Fuse PLC Figure 3. supports fast charging with a current up to 30 A per string. State of charge (SOC) window for fast charging. Current sensor LMU LMU-pack DC/DC Converter PLC LMU LMU-packs Common voltage bus High Field bus HMI LMU

I

I+ 26

Configuration

In a common voltage bus system, with a fixed voltage Battery size is determined by a number of application- window, the battery capacity required to meet the specific features such as voltage window, load profile, designed run time of the battery is determined by the required run time and recharge opportunities. System number of strings connected in parallel on the common design should also be considered. For instance, a system voltage bus. Each string increases the battery rated supported by photovoltaic arrays will require a different capacity by 10 Ah. The rated battery energy equals the battery size than a hybridised system powered by a rated pack energy in Wh multiplied by the number of combustion engine and a battery. Charging infrastructure packs in the battery. is also important: the number of charging stations or frequency of short recharging together with installed charger power will impact the optimum battery size.

Table 1. Nominal string voltage as a function of pack size and number of packs in series.

Nominal string voltage [V] Battery pack Nominal pack voltage [V] Number of packs in series per string 60 HV 60V 10Ah 60 1 72 HV 72V 10Ah 72 1 84 HV 84V 10Ah 84 1 96 HV 96V 10Ah 96 1 108 HV 108V 10Ah 108 1 120 HV 120V 10Ah 120 1 144 HV 72V 10Ah 72 2 168 HV 84V 10Ah 84 2 180 HV 60V 10Ah 60 3 192 HV 96V 10Ah 96 2 216 HV 108V 10Ah 108 2 240 HV 120V 10Ah 120 2 252 HV 84V 10Ah 84 3 288 HV 96V 10Ah 96 3 300 HV 60V 10Ah 60 5 324 HV 108V 10Ah 108 3 336 HV 84V 10Ah 84 4 360 HV 120V 10Ah 120 3 384 HV 96V 10Ah 96 4 420 HV 84V 10Ah 84 5 432 HV 108V 10Ah 108 4 480 HV 120V 10Ah 120 4 540 HV 108V 10Ah 108 5 576 HV 96V 10Ah 96 6 588 HV 84V 10Ah 84 7 600 HV 120V 10Ah 120 5 27

Installation

A typical battery installation is shown in Figure 4. Battery packs are installed by laying on one of the long sides with the monitoring unit facing outwards for easy access during installation. Battery packs are secured to the support structure with screws and brackets.

The footprint of a typical 600 VDC installation with an installed energy of 48 kWh is shown in Figure 6. Strings are installed horizontally with 5 battery packs, of type HV 120V 10Ah, connected in series in each string. 8 strings connected in parallel on the common voltage bus equals a rated battery capacity of 80 Ah, corresponding to 48 kWh. Figure 4. Typical battery installation. Dimensions in Figure 6 are based on a battery pack type HV 120V 10Ah.

Figure 5. Cabinet with installed PLC, circuit breakers and fuses.

Figure 6. Typical dimensions (mm) of a 600 VDC installation with an installed energy of 48 kWh. 28

Nilar system components

Battery packs

Nilar energy storage solutions use Nilar bi-polar battery packs with cells in serial configuration. The Nilar 1.2 kWh 120 VDC modular pack can deliver up to 7.2 kW (6C) of power over a short period, or 4.8 kW (4C) for cyclic applications. The range of available packs and specifications are shown in Table 2. Dimensions and weight are specified for battery packs with mounted monitoring unit and without connectors and current Figure 7. sensor. Nilar battery pack type HV 120V 10Ah fitted with monitoring unit. Table 2. Nilar solutions pack range. Battery pack Nominal Rated Energy Weight Width Lenght Height voltage capacity [Wh] [kg] [mm] [mm] [mm] [V] [Ah] HV 60V 10Ah 60 10 600 16.2 206 329 165 HV 72V 10Ah 72 10 720 18.8 230 329 165 HV 84V 10Ah 84 10 840 21.4 254 329 165 HV 96V 10Ah 96 10 960 23.9 278 329 165 HV 108V 10Ah 108 10 1080 26.5 302 329 165 HV 120V 10Ah 120 10 1200 29.0 326 329 165

Monitoring unit The monitoring unit is mounted on each battery pack. The unit is monitoring potentials for every 10 cells in the pack Architecture Interfaces together with pack temperature and pressure. Processed – ARM Cortex M10 microprocessor Isolation boundaries (designed for a distributed and • Power supply to AGND (500 data is communicated via a field-bus interface to the PLC. scalable topology in a slave unit VCD) The monitoring units are powered by an external power configuration) • CAN Bus to AGND (1.5 kVDC) supply of 24 VDC (not from the pack). As this system is Sensing • Voltage monitors to AGND (3 kVDC) connected to a common voltage bus, the monitor will issue – 10 voltage channels with 8 to 18 V range Input Power warnings to the PLC if string isolation is warranted. The – 1 external pack temperature • 24 V – supply power range from communication between the PLC and the monitoring unit – 1 internal ambient temperature 18 to 36 VDC is a CAN bus using the CANopen application programming – 2 external currents using hall • 5 V – CAN Bus power (no CAN interface. CANopen uses ISO-11898:2003 standard CAN sensor power supply installed) – 1 external pack pressure with an 11-bit identifier. The range of bus signalling rates Communications interface Functions • CAN/CANOpen is 125 Kbps to 1 Mbps. The monitoring unit bus rate is set Limit flag reporting Connectors to 250 Kbps. • Module voltage • Input power: Phoenix • Current PTSM_1803293 (Green) 4 pin • Pressure • CAN: Shielded RJ45 8 pin • Temperature • Current sensor connector • High density 15 pin D-Sub – 10 pack voltages – Pack temperature – Pack pressure

Figure 8. Monitoring unit. 29

Programmable logical controller (PLC) Nilar uses an Eaton PLC type XC200 as a master node for the distributed monitoring units. Other types of PLC are available on request. The PLC is programmed with Nilar BMS software for management of the battery and interaction with higher level systems. Up to 36 monitoring units can be connected to one PLC. The XC200 series modular PLCs are of scalable design and support Figure 9. integration in modern communication systems. This Eaton XC200 PLC. allows for energy storage systems with more than 36 battery packs by use of additional PLCs.

• On board 14 I/O points • Integrated web server • Locally expandable with up to • On board high speed counter 15 XIOC modules inputs • On board RS-232 serial • On board encoder inputs interface • Ethernet, CANopen, PROFIBUS • On board CANopen interface DP, easyNet • On board Ethernet and Suconet K communications

Circuit breaker Figure 10. Battery pack with mounted Two circuit breakers per string are required to enable current sensor. disconnection of the string from the common voltage bus. The circuit breakers are hardwired to and controlled by the Current sensor PLC. Circuit breakers can be provided on request. I

Fuse I+ Two fuses per string are recommended, one on the negative and one on the positive side and located close Figure 11. Location of current sensor. to the string. Fuses can be provided on request.

Current sensor

The current sensor provided by Nilar is an automotive grade current transducer of type DHAB S/44 produced by LEM. It has galvanic isolation between the primary circuit (high power) and the secondary circuit (electronic circuit). Figure 12. The open loop transducers use a Hall-effect integrated Current sensor. circuit. There is one current sensor per string, mounted on the battery pack on the negative side of the string. • Good accuracy for high and low • Unipolar + 5 V DC power supply current range • Primary current measuring • Good linearity range up to ± 20 A • Low thermal offset drift • Operating temperature range: - • Low thermal sensitivity drift 40 to + 125 °C • Hermetic package • 2 measuring ranges for • Low voltage application increased accuracy. 30

Notes

Nilar AB Headquarters and Sales Stockholmsvägen 116 B SE-187 30 Täby Sweden Phone: +46 (0)8 768 00 00 Email: [email protected]

Nilar AB R&D and Production Bönavägen 55 Box 8020 SE-800 08 Gävle Sweden Phone: +46 (0)26 960 90 Email: [email protected]

Nilar Inc. Sales USA Suite 525, 10800 E. Bethany Drive Aurora, CO 80014 USA Phone: +1 720 446 0169 Email: [email protected]

Visit our website at www.nilar.com/contact to find out who your local distributor is.

www.nilar.com Nilar Doc. No.: 73-F003-R03