Lead-Acid Starter Batteries in Systems Usage Information

Batteries Association

ZVEI information leaflet No. 28e Edition October 2017

Lead-acid starter batteries in systems Usage information

Preliminary note: This information leaflet aims to help to choose batteries and develop design solutions and operating manuals by providing general information on the usage of lead-acid batteries in vehicles, which extend beyond the relevant standard specifications. This information serves as a recommendation only, and not as a substitute for the battery user’s responsibility to make appropriate decisions. By pooling all gained experience to date, however, it should make the decision easier.

Contents 1. General ...... 2 2. Mechanical loads...... 2 2.1. Battery installation...... 2 2.2. Vibration stress...... 3 3. Thermal stress...... 3 3.1. Battery temperatures...... 4 3.2. Possible measures regarding thermal loading ...... 4 4. Electrical loads ...... 4 4.1. Electrical battery integration into the vehicle ...... 4 4.2. Battery voltage...... 5 4.3. Battery currents ...... 6 4.4. Limits of cyclical loading ...... 6 5. Installation space of the battery...... 6 5.1. Battery ventilation...... 6 5.2. Protecting against corrosion caused by battery acid...... 7 5.3. Electrostatic discharge (ESD)...... 8 5.4. Splashing water ...... 8 5.5. Direct light exposure (UV)...... 8 5.6. Battery environment...... 9 5.7. Battery installation direction in the vehicle...... 9 5.8. Signs and warnings...... 9 6. Regulations for interconnecting batteries...... 9 6.1. Batteries connected in series ...... 9 6.2. Parallel battery connections ...... 9 6.3. Combined series and parallel connections:...... 9 7. Repair and maintenance information ...... 9 7.1. Frozen batteries ...... 9 7.2. Installation and dismantling batteries...... 9 7.3. Checking and correcting electrolyte levels ...... 9 7.4. External charging ...... 10 7.5. External start-up ...... 10

This leaflet was prepared by the Working Group Starter Batteries of the ZVEI – German Electrical and Electronic Manufacturer’s Association 1. General fixed in, the tray must be 2.1.4 One-piece cover as per designed in such a way so as to EN 50342, parts 2 and 4 Lead-acid batteries as defined enable the multiplied battery by this recommendation fulfil weight resulting from strong These European standards their function during engine vibrations or a crash to be describe batteries with flat start-up, when supplying power absorbed. covers. In these batteries, the to the on-board electrical end terminals, and in some system, and while smoothing the The various battery types enable cases also the cell cap stopper, system’s voltage. A series of different installation options: sit beyond the cover. Typical instructions must be followed fastening devices include full when using lead-acid batteries frames or brackets with tie rods to ensure customer satisfaction running vertically to the battery’s 2.1.2 Base hold-down bars as transverse axis. The fastening in terms of maximum product per EN 50342-2 reliability. These instructions are devices must be mechanically based on the battery’s This European standard stable, and screwed snugly into dependence on mechanical, describes base hold-down bars the base plate. The fastening thermal and electrical influences, running around the long and devices must be designed in and take into account safety front sides. These standardised such a way so as to absorb any aspects. base hold-down bars have a forces applied to the battery. clearly specified profile. They Additional protection against This information leaflet contains also have standardised beading slipping sideways is required. recommendations for safe at set locations. The structural See 2.1.5 for the permitted handling of these batteries. It elements required to affix the clamping forces. does not replace the industrial battery, such as terminal strips, work instructions issued by the clamps etc., are responsible for OEM, the usage instructions positioning the battery in the 2.1.5 Permitted clamping forces provided by the vehicle tray, fastening it down and protecting it from sliding to the The battery cases are generally manufacturer, or the vehicle made from polypropylene. operating manual. side. The fastening devices must be mechanically stable, and EN 50342-5 establishes the requirements for materials, Following a wide range of screwed snugly into the base plate. The fastening devices and battery boxes and covers. One requirements, optimised of the properties of batteries are used for special elements must be designed in such a way so as to absorb any polypropylene is that it yields usage conditions in addition to under loads. This means that it standard batteries. Special forces applied to the battery. Slide protection is ideally takes only a change in usage conditions include high temperature to significantly mechanical loads, high thermal provided using lugs which protrude into the base hold- reduce the clamping force loads and specific electrical applied by initial fastening. Even loads. Particular attention must down bars’ beading. The fastening devices must be able high clamping forces will not be paid to the safety-related change this, resulting in plastic properties. to prevent any damage to the battery. See 2.1.5 for the deformation in the case walls. permitted clamping forces. When fastening the battery The installation location, using the base hold-down bars, operating conditions and choice a certain degree of plastic of battery must all be in tandem deformation in the base hold- with one another. These 2.1.3 Covers as per down bars is required in order to guidelines are designed to help EN 50342-2 permanently fasten the batteries. with this and explain the finer This European standard Excessive deformation destroys details. describes batteries with covers, the case. For this reason, whose tops have defined bottom-bar deformation should recessed sections on both of the not exceed 15% of the bottom 2. Mechanical loads long sides. The resulting section bar’s height during assembly. is ideal for top-down fastening. 2.1. Battery installation Typical fastening devices NOTE: Bottom-bar battery include brackets running fastening is a hyperstatic system 2.1.1 The battery tray crossways to the battery with tie to which the construction rules of The battery tray is the rods. The fastening devices mechanical engineering cannot designated battery receptacle on must be mechanically stable, be applied in relation to plastic the vehicle. It must be and screwed snugly into the deformation. The following mechanically stable, and base plate. The fastening structural features must be fine- fastened firmly to the vehicle. devices must be designed in tuned in theory and through The fastened battery tray must such a way so as to absorb any experiments: The rigidity of the be attuned to the dynamic loads. forces applied to the battery. bottom bar in terms of Excess mechanical loads on the Additional protection against construction and materials, the batteries must be avoided. It is sideways sliding is required. See size of the clamp area, the beneficial to have a support 2.1.5 for the permitted clamping deformation trajectory and the running around the entire forces. tightening torque in relation to outside of the battery base. In the screw-thread diameter the area where the battery is (thread pitch depends on thread diameter). 2/10 When fastening using the cover, battery's resonance frequency The battery’s optimum operating the surface loading depends on have a particularly critical effect temperature is between +20 and the respective construction’s +40 °C. Lower temperatures cover (battery cover design, and As a result of its structural limit both its charging capacity location and design of the design the battery itself and its performance, while holder), and must be designed constitutes an active resonant higher temperatures increase separately for each individual system. This is made up of the self-discharge, wear-out, and case. It is important to ensure elastic plastic case, the plate water consumption. that the battery’s total load is packs affixed in the case, and generally no more than 10 times the acid moving freely within the The battery can heat up through the battery weight, and that the cells. The three-component external heat sources via heat surface load does not exceed system generally displays two conduction, radiation and/or 1 N/mm² for unsupported cover distinct resonance frequencies convection, or through a loss of areas and a maximum of which vary depending on the heat within the battery. 6 N/mm² for cover areas respective battery’s design. supported by a partition. Extreme temperatures cause Typical resonance frequencies specific risks: lie within the following ranges: - In the event of overheating, it is 2.1.6 Protection against lateral - 10 to 30 Hz (for the acid important to note that, in movement resonance) addition to greater aging/wear - 90 to 120 Hz (for the plate out, VRLA batteries in The battery should be fastened pack resonance) particular can fail as a result of in such a way that any the “thermal runaway” effect. movement in an X/Y and Z If the acid resonates, it may leak This is the term used to direction is prevented. In out of the battery. If the plate describe the battery’s thermal addition to being held down, the pack resonates, the plates may self-destruction, as power input battery should also be protected break and/or the bridge between rises uncontrollably when against lateral movement. the electrodes and affixed pole overheated batteries are Batteries installed next to one may crack. Internal sparking charged, causing the extra another must be kept far enough may then cause the battery to heat released to escalate. Acid apart so that their covers do not explode. may leak as a result. touch. Any height differences of - For temperatures below zero, batteries standing next to each Structural arrangements on the power intake drops to almost other should be taken into vehicle can influence the impact nil, meaning the amount of account. of the vibration. Batteries with power withdrawn from the higher vibration resistance can battery is not recharged quickly In the event of fastening using be used if necessary: enough. It must also be noted base hold-down bars, lateral - Batteries with a fixed that the battery acid’s freezing movement can be prevented by electrolyte (sealed VRLA point increases as the acid lugs in the clamps and/or technology) absorb a lot of the density decreases. The acid’s terminal strips which grip firmly resonance in the plate pack density drops during discharge into the base hold-down bars’ and the acid. when the depth of discharge ribbing. - In the case of conventional increases. Typical values batteries, the plate pack’s include: vibrations can be absorbed - a fully charged battery 2.1.7 Battery behaviour in a through suitable engineering freezes only at crash measures. EN 50342-1 defines around -70°C, the various requirement - a half-charged battery will Due to its large mass, the categories. freeze at -20°C, and battery can pose a particular risk - a fully discharged battery will to persons directly or indirectly freeze at just 0°C. involved in a crash. The following measures help reduce 3. Thermal stress Caution: Frozen batteries can these risks: burst, and acid will leak out once - Choose a suitable installation Batteries are electrochemical it is thawed. Charging frozen location, energy storage devices. batteries can also cause - Allow the battery to be pinned Chemical processes are known explosions. by the bodywork, or to depend heavily on - If necessary, secure the temperature. In a first-order The battery should thus be kept battery additionally. approximation, the reaction at a charge which prevents it speed doubles per 10 K from freezing, in accordance temperature increase and halves with the expected operating 2.2. Vibration stress with a 10 K temperature temperatures. reduction. The battery tray transfers the Major temperature differences in vehicle vibrations directly to the the battery or battery pack cause battery. The stress is determined the cells to work unevenly, by the frequency spectrum and resulting in an early failure of the associated amplitudes. battery. Frequencies close to the

3/10 3.2.4 Servicing measures Valve-regulated In regions involving extreme Flooded batteries lead-acid climatic conditions, users may batteries – VRLA be recommended to take the following measures: Upper temperature 60°C 55°C - Battery maintenance (acid level checks, water refills, Difference within external charging, external battery/within battery 10 K 6 K temperature controlling), assembly - Adjusting maintenance intervals, or - 40°C Lower temperature - Limiting usage time. Note chargeability and freezing point. 1) Cumulative temperature peaks of 80°C over 3 hours of usage are permitted. 2) It is important to note that, in the same ambient conditions, VRLA batteries 4. Electrical loads heat up faster than flooded batteries due to the internal recombination cycle. 3) If, based on design, the VRLA is suitable for operation in temperatures above 55°C, the temperature provided by the battery manufacturer is used as a 4.1. Electrical battery recommendation, e.g. 60°C integration into the vehicle Table 1: Operating temperature range inside the battery The battery has preferred terminal locations and shapes to ensure safe integration into the on-board electrical system. The 3.1. Battery temperatures 3.2.2 Measures combating connection elements on the battery problems In keeping with the general battery cables must be attuned resulting from low to the shapes and material information above, the batteries temperatures should be used within the properties of the terminals in operating temperature range Possible measures to combat such a way so as to guarantee a (acid temperature) shown in low battery temperatures may permanent, force-locked Table 1: include the following – connection. individually or in combination: The shape and location of the - Thermal insulation, terminals are largely established in the standard EN 50342, part 2 3.2. Possible measures - A warm installation location (for cars) and part 4 (for regarding thermal (use heat sources in the commercial vehicles). loading vehicle, additional heating), or - Battery-temperature-controlled charging using a charging The battery terminals are made 3.2.1 Measures combating from lead or a lead alloy. The battery problems at high voltage gradient of -24 mV/K per 12 V unit, see point 4.2.1. terminal bushing is partially temperatures hollow, and the ductile behaviour Possible measures to combat of lead under permanent high battery temperatures may 3.2.3 System measures mechanical loading must be include the following – either taken into account. When individually or in combination: The system itself can also help building the connection clamps - Cool installation location (note compensate for extreme and defining the associated the location of the cooling and temperatures or the tightening torques, it is therefore exhaust system), consequences thereof: important to ensure extensive, - Ventilated installation system - Choice of battery (technology, consistent compression of the preventing external and internal design, acid density), terminal which causes minimal internal heating, heat shield, - System tuning (generator, on- deformation. When building the water traps/cooler traps, board electrical system, clamps it is also important to complete heat protection for battery), note that the loosening and the battery (insulation, provide - Temperature monitoring using connection process may need to space for insulation), or active temperature manage- be repeated several times. The - Battery-temperature-controlled ment of the battery, fact that the terminal gets charging using a charging - Charge status monitoring with narrower with every connection voltage gradient of -24 mV/K active energy management for process must be taken into per 12 V unit (see point 4.2.1). the battery, or account. When using terminal - Ensure easy battery removal grease, check to see how it so that the battery may be affects the clamp’s fit. recharged externally. The design of the terminal clamp and the fastening tool must be attuned to one another in such a way that the terminal, battery cover and plate groups are not damaged when the battery is connected by laypersons. Using

4/10 force to open the clamp (hammer) or applying a bending or torsional moment (leverage) beyond 10 Nm is not permitted. Upper limit Lower limit Characteristic Depending on features, a vehicle model will generally contain different sized batteries. The following is thus recommended: Battery [V] voltage - Ensure the length of the electrical cable is such that the battery can only be connected

to the terminals of correct Battery temperature [°C] polarity, - Ensure the length and flexibility Figure 1: of the cables are such that no Double kinked characteristic curve for 12 V batteries when excessive bending moments charging in the vehicle (Characteristic curve gradient: -24 mV/K). can statically or dynamically be applied to the battery dependent on temperature AC-current loads than batteries terminals, (voltage measured at the battery containing liquid electrolytes. - Ensure the dimensions of the terminals, temperature wiring harness are such that measured inside the battery). Depending on the shape of the the charging voltage stated in current curve and on the basic point 4.2.1 is upheld. System-optimised charge charge status, frequencies up to - Cables and hoselines touching characteristic curves should be 500 Hz can, even with low the engine must be kept in a discussed with the battery charge flow, cause microcycling safe distance from the battery, manufacturer. Special charges, in the battery, which can lead to otherwise engine vibrations such as recuperation (recovery acid stratification, early wear-out can cause the battery case to of braking energy, recovery of of the active materials and wear through, resulting in actuators) or external charges reduced battery life. AC-current possible acid damage to the should also be discussed with loads within the kHz range are vehicle parts. the battery manufacturers if they relatively harmless. lie outside the aforementioned Non-grounded terminal charge characteristic curve Measures combating AC-current connections must be protected (Fig. 1). loads include: against short circuits. - Adjusting battery size and NOTE: The battery is not an battery technology, electric component in the sense - Adjusting the on-board 4.2. Battery voltage of ISO 16750-2. electrical system (avoiding battery overload, using During charging, the optimum 4.2.2 Superimposed alternating inductance and/or additional charging voltage depends on the capacities). battery design, battery current temperature and load profile. The battery operates as a buffer 4.2.3 Discharge voltages Excessively high charging in the electrical system of the voltages create more gassing in vehicle. The generator and The battery’s minimum state of the battery, resulting in the risk alternating devices create an charge is generally determined of acid leakage. At the same additional AC-current load on by the start-up requirements, time, water consumption is the battery, giving the charging and is thus usually more than increased and lifetime reduced. or discharging current the 50%, based on the battery’s Excessively low charging properties of an AC current. nominal capacity. Lower battery voltages lead to insufficient Depending on charge balance, discharges are possible, but charging, persistent sulfation the battery’s charge status, negatively affect the battery and the risk of freezing. battery temperature and battery lifetime. Discharges over 80% of design, the amplitude and the rated capacity should To protect the battery, lead frequency of the AC-current can particularly be avoided. Staying batteries should not be affect the battery’s durability. permanently at low state of discharged below current- They have been known to cause charge also causes damage and dependent voltage limits. On the various types of damage, early failure. Occasional current other hand, supplying safety- dramatically reduce battery life peaks, e.g. at start-up, are not related devices takes but also produce positive effects. critical and do not require the precedence over battery discharge voltage to be limited in protection. An additional AC-current load any way. during the charging phase 4.2.1 Charging voltages always results in extra battery The end voltages tuned to an heating. Current experience has 80 % depth of discharge depend Figure 1 shows a charging- shown that sealed, fully charged on the respective load current. voltage characteristic curve batteries are more sensitive to The final discharge voltages optimised for the battery and

5/10 Specific discharge current 0.0005 0.005 0.05 0.25 1 3 5 IE per C20 [A/Ah]

Final discharge voltage 11.7 11.7 11.7 11.6 11.3 10.2 9.3 UES [V] Table 2: Final discharge voltages

(UES) shown in Table 2 apply to 4.3.1 Measures combating Possible measures for 12 V batteries and the load excessively high battery currents combating early failure caused currents standardised at a rated by cyclical loading: Various measures can be taken capacity of C20. For batteries - Co-ordinating the generator with a rated voltage differing on the vehicle individually or in and electric components; from 12 V, the end voltages combination with each other in - Quiescent current must be converted linearly in order to prevent short circuits in management to avoid accordance with the rated wiring and batteries: excessively low discharges; voltages. - Suitable installation space, - Charging voltage adjusted to The permitted voltage limits - Protected cable routing, battery temperature; stated in ISO 16750 have to be - Using terminal covers, - Choice of battery (size, design, considered for the electric - Using main fuses, charging dynamics) or components. - Multi-battery on-board - Avoid extreme battery electrical system, temperatures. The following measures are - Using suitable batteries recommended to prevent any prohibited voltage drops: 5. Installation space of the - On-board electrical system battery layout (Generator/electric 4.4. Limits of cyclical loading components/wires) 5.1. Battery ventilation - Battery size and design, Cyclical loading means the - Disconnect individual devices, alternation of charges and A mixture of hydrogen and - Increase rate of rotation. discharges. A battery’s capacity oxygen is generated in the for cyclical loading is defined as battery as a result of water the number of charge and electrolysis and self-discharge. discharge cycles before the 4.3. Battery currents This process occurs under all battery fails. With optimum operating conditions (charging, Car batteries are not short- temperature and charge, the discharge and quiescent circuit-proof. During a short achievable number of cycles is phases), and particularly arises circuit in an unprotected part of essentially determined by the when the battery is charged the on-board electrical system average depth of discharge. The beyond the so-called gassing (battery main, starter line, product of the number of cycles voltage. generator line), batteries can and the capacity lost per cycle is The battery under all release very high output over an first-order approach to setting circumstances needs a gas extended periods of time. a characteristic cycle lifetime for exchange with the surrounding Excessively high currents, such a specific battery. atmosphere. The battery as those occurring during a short degases through the cap or circuit in the on-board electrical The cycle lifetime actually plugs on each individual cell or system, may cause the battery’s achieved in the vehicle is through the side opening of the internal lead connections to melt determined by charging voltage, central degassing unit. Acidic and break connection. The charging balance, battery design droplets can escape with the resulting sparks can lead to and battery temperature. gases, and these aerosols can battery explosion. cause corrosion in the area Batteries which around the battery. These gases Experience has shown that the - are permanently operated in a are usually explosive, depending load currents and load times low charging state, on their composition. stated in Table 3 are non-critical. - are charged with excessively low or high charging voltages, - are cycled under extreme 5.1.1 Formation of battery battery temperatures, gases have heavily reduced cycle The gassing voltage marks the lifetimes. voltage at which substantial gassing begins. This voltage depends on the battery’s technology, age and Load time [s] 0.5 2 10 30 > 30 temperature. 14.4 V (= 2.4 V/cell) is considered a Load current reference value for a new 3 2 1.3 1 0.6 [Icc] battery’s gassing voltage at room temperature. Table 3: Load current/Load times

6/10 In a fully charged battery, almost - System for collecting leaking could affect degassing in the all of the charging power is used acid (droplet trap, tray), event of frost). to decompose electrolyte water. - No corrosion-sensitive - Do not let the hose opening The charge quantity of one components near the battery, end in areas of intensely low or ampere hour thus decomposes or high pressure. 0.34 g of water, forming 0.42 L - Battery cover systems with - Maintain an adequate distance of hydrogen and 0.21 L of acid collection/separation between the hose end and oxygen at 20°C and 1013 hPa. function. ignition sources. - Add a note that the hose must Towards the end of battery life, 5.1.2.1 be reinserted after short circuits may also form in Suitable installation place design maintenance work. one or more battery cells. In this - Use batteries whose cell plugs case, the generator’s charging Installation spaces should be or caps remain leak-proof for voltage remains the same but is designed in such a way so as to the battery’s entire lifetime, or spread over just a few non- keep hydrogen concentration which have plugless battery short-circuited cells, meaning it below the ignition limit of < 4 % covers. may significantly exceed the when diluting escaping gases. - Add a note that, in the event of gassing voltage in the remaining battery replacement, only cells. A defective regulator can Possible measures for doing so batteries with the same design also cause the charging voltage are: can be used. to rise incorrectly, and more - Designing the installation - Some vehicles are equipped gassing and corrosive aerosols space so that natural with a hose with an attached to be produced. ventilation will suffice, connector to drain off the - Ensuring adequate external battery gases. If this is the A hydrogen/oxygen mixture can ventilation in the installation case in that vehicle, the hose be ignited within a hydrogen space, or must be inserted into the concentration range of 4 % to - Discharging the battery gases corresponding degassing 96 %. Ignition energy of just from the installation space. opening of the battery via the 0.01 joules will suffice. The connection piece. If an escaping gas mixture can See also the relevant safety additional degassing opening generally be ignited, and the requirements in standards EN is provided on the other side, ignition can potentially continue 50272 or IEC 62485. this must be closed with a straight into the battery. closure plug. Under no 5.1.2.2 circumstances must both It is therefore necessary to take Adequate distance from openings be closed. measures which minimise the ignition sources risk of battery explosions. These It is important to maintain an measures must remain effective adequate distance from ignition 5.1.2.4 for the entire duration of vehicle sources in order to keep Prevent flash-back usage. This also applies to the hydrogen concentration below replacement battery, which must Preventing flash-back means the ignition limit. This requires meet at least the same taking additional measures to suitable inspections or requirements as the original reduce the risk of explosion calculations. The standards EN battery. during external ignition. It 50272 and IEC 62485, involves using a special “filter” to respectively, provide the prevent a spark outside the relevant information. 5.1.2 Measures to avoid battery from crossing into the damage from battery battery. Despite this clear 5.1.2.3 gases benefit, it is also important to Specific discharge of note that this filter delays the Possible measures to prevent battery gases venting of explosive gases from damage caused by battery the battery. Collecting the battery gases in a gases/aerosols near ignition central degassing pipe enables sources and/or corrosion- the gases and aerosols to be sensitive components are: 5.2. Protecting against directed out of the battery - Suitably designing the corrosion caused by environment or battery box in a installation space (see 5.1.2.1), battery acid controlled manner through a - Maintaining an adequate standardised degassing vent in distance from ignition sources Batteries contain highly the cover, combined with a gas (see 5.1.2.2) or corrosive, diluted sulphuric acid diversion hose. - Specific discharge of battery as an electrolyte. When batteries gases (see 5.1.2.3), are installed in a vehicle’s It is important to note the interior (the boot is also following here: Additional measures to reduce classified part of the interior in - Ensure unimpeded degassing damage: the event of fold-down back through straight, non-kinked - Choosing suitable batteries, seats), it is important to avoid piping. - Inhibiting re-ignition in the physical injury caused by leaking - Lay the hose in a continuously battery (see 5.1.2.4), battery acid. The possibility of downward sloping position to - System co-ordination people being contaminated with avoid water collecting (this (regulator, battery), battery acid can be reduced or

7/10 prevented by measures at both e.g. by cleaning the battery case 5.3.2 Measures in the battery’s the vehicle and battery level. with a dry cloth, dragging the surrounding environment battery over carpet, or rubbing The environment can also help 5.2.1 Vehicle-based measures surfaces/objects in the battery’s immediate environment. Friction keep ESD away from the battery Corrosion caused by battery causes electrons to move from mounted in the vehicle: acid can, for example, be one surface to another, thereby - People need to be sufficiently prevented by housing the battery electrostatically charging the discharged, e.g. by touching in a completely covered surfaces or objects. conductive parts connected to compartment. the bodywork material. This is only possible with non- - In the battery’s immediate 5.2.2 Battery-based measures conductive materials/objects. surroundings, the charge is Very high electrical voltages or diverted through materials with The batteries mentioned below potentials in the multi kV range a minimum conductivity of are designs featuring specific -4 -1 can develop, and, depending on 10 Sm and contact with the properties. In the event of the conditions (type of materials, vehicle material or battery replacement, users must be friction and air humidity), the terminal. instructed to use a battery with charge may be equalised by an at least the same design ignition spark (electrostatic features as the original (e.g. on discharge, ESD). The sparking a sign near the battery or in the occurs through the air as a result 5.4. Splashing water vehicle’s operating manual). of a charge equalisation between two surfaces with If large amounts of splashing 5.2.2.1 differing electron concentrations. water hit the battery, they quickly Optimised tilt-angle batteries The air is ionised, meaning cause the battery’s gas compartment to cool down. This Batteries with optimised tilt angle conductive, due to the high electrical potential. As a rule of creates low pressure in the meet special requirements. For battery, which sucks water example, they retain the liquid thumb, every 1kV of potential difference can pass an air gap of flowing over the battery’s cover electrolyte even when turned into the battery through the side upside down and while being 1 mm. This value is heavily influenced by air humidity. opening of the central degassing charge, and so reduce the risk of unit or through unsealed plugs acid leakage for a limited time. Sparking can also occur by or caps. If this process is entrance of a charged person or repeated multiple times, the 5.2.2.2 overfilled battery may leak acid. Batteries with a fixed electrolyte object coming into close proximity of the battery. It makes sense to use batteries It is important to prevent the with a fixed electrolyte, a so- The ignition spark energy battery from being constantly called VRLA battery (VRLA = needed to ignite the gas mixture flooded with splashing water. Valve Regulated Lead Acid; inside the battery is so low that collective term for AGM and gel the spark may not necessarily Protective measures include: batteries). be perceptible to the human eye. - Choosing an installation Due to the complexity of this location with no splashing topic, it is referred to the relevant water, 5.3. Electrostatic discharge literature. - Sealing the central degassing (ESD) unit’s opening with an elbow fitting or similar, 5.3.1 Battery-based measures The hydrogen/oxygen mixture, - Use a cover hood for the almost always present in the At the battery level, the ESD risk battery, or battery’s gas compartment, is can be reduced by using - Choose batteries protected explosive and may be ignited by batteries with a high contact against flooding (cell plugs with a spark. An ignition spark may resistance between their exterior sealing ring, batteries without also arise as a result of and interior. The main factors cell plugs or whose cell plugs electrostatic discharge. are: have been covered, degassing - Material thickness of the hose, protected terminals) As the battery case is made of battery case; plastic and is an electric - Refraining from using cell insulator, the inside of the plugs or caps, or 5.5. Direct light battery can have a different - Cell plugs or caps with a high exposure (UV) potential than its surrounding contact resistance around the environment. This difference in seal; The UV components in sun light potential is equalised as - Sticking a non-conductive label cause the battery case to electrostatic discharge. over the cell stoppers; become brittle, potentially - Spraying the batteries with resulting in case ruptures and People or objects are antistatic spray (temporary acid leaks. electrostatically charged through effect). charge separation or transfer. Possible protective measures Charge separation can occur as include: a result of friction by/on - Choosing an appropriate chargeable surfaces or objects, installation location,

8/10 - Installation the battery in a 6.1. Batteries connected in 7. Repair and maintenance separate box or in a light- series information stabilised battery case, and - Ensuring light protection during To avoid reduced battery The following information should storage. lifetime, it is important to ensure be appropriately included in the the following when connecting workshop service instructions multiple batteries in series: and vehicle operating manual. 5.6. Battery environment - The charging voltage stipulated by the battery manufacturer 7.1. Frozen batteries The battery should be mounted should be present at every into the vehicle in such a way so battery’s terminals; The freezing process damages as to maximise the ease of - The individual batteries should batteries, which is why it is not installation and dismantling (e.g. have the same operating recommended to use a frozen accessibility, short circuits, temperatures wherever battery. If, despite all care taken, ESD). possible (otherwise use a battery should still freeze, it is temperature-controlled battery important to note the following: The battery’s surrounding management); - Wherever possible, dismantle environment must not contain - The individual batteries should the battery before it thaws; any pointy or sharp objects be loaded as consistent as - Thaw the battery in an acid- which could destroy the battery’s possible (use intermediate taps proof container, collect any case during usage, installation with equalising charge and/or leaking acid; or dismantling. discharge management). - Dispose of the defective battery and any leaked acid 6.2. Parallel battery appropriately. 5.7. Battery installation connections direction in the vehicle To avoid a reduced battery 7.2. Installation and In the case of wet-cell batteries lifetime, it is important to ensure dismantling batteries with built-in measures to prevent the following when connecting acid stratification, it is important multiple batteries in parallel: The battery manufacturer’s to follow the manufacturer’s - Only batteries with the same manual should serve as a recommendation for installation. voltage, design and (as close guideline for the vehicle as possible) age should be manufacturer’s documentation Horizontal installation in the connected, and (operating manual, workshop vehicle is recommended for wet- - The same charging voltage (or service instructions). cell batteries. as similar as possible) should be present at every battery’s terminals (either by equalising 7.3. Checking and correcting 5.8. Signs and warnings the cable lengths and cross- electrolyte levels sections or through a special In accordance with EN 50342, charging circuit), and Batteries consume water during batteries must be labelled with - The individual batteries should operation. A distinction is made safety symbols. The symbols have the same operating between batteries which allow should remain visible, or have temperature (or as similar as maintenance and those which reference made to them, even possible) and do not. when working on installed - Unwanted interaction between batteries. These symbols are batteries (e.g. unintentional Batteries with excessively low explained in the battery’s usage compensating current flows electrolyte levels must be manual, together with other resulting in uncontrollable maintained or replaced. safety-related information. battery and cable warming and loss of charge) should be Operating batteries with reduced through suitable excessively low electrolyte levels 6. Instructions for connection measures. can result in considerable interconnecting batteries damage. 6.3. Combined series and Batteries in vehicles are always parallel connections: Electrolyte levels should be connected parallel to the charger regularly checked, and should and electric components. Combined series and parallel be corrected by a specialised Depending on the requirements connections can cause early workshop. In the case of of the vehicle’s on-board failure due to uneven charging of batteries which permit electrical system, batteries are individual batteries. Appropriate maintenance, it is important to connected compensation measures must note that: - in series to increase voltage, or therefore be stipulated in such - The electrolyte must only be - parallel to increase total cases. topped up with demineralised capacity and/or combine water, and by no later than at various functions. the time the minimum on an acid level indicator or similar is reached, and

9/10 - The liquid must not be topped No electrolytes or water must be Charging information must be up beyond the maximum mark refilled in the case of sealed included in the operating (otherwise acid can leak). batteries (VRLA). manual/service instructions. - When filling the battery with demineralised water, make 7.5. External start-up sure no foreign matter or fluids 7.4. External charging A description of an external get into the battery. start-up must be included in the - The battery surface and External charging should only be vehicle’s operating manual. environment must not be performed by a specialised contaminated with acid. workshop. Even when using batteries which do not enable maintenance, it is Only suitable chargers must be important to note changes in used. Users should be instructed electrolyte levels during usage. If as follows: the minimum indicator is - Follow the charger reached, the battery needs to be manufacturer’s or battery replaced. If the levels cannot be manufacturer‘s usage checked, a maximum usage instructions and duration needs to be defined. - Check electrolyte levels before charging, and equalise if necessary (see 7.3). Batteries with excessively low electrolyte levels must not be recharged.

Editor: ZVEI – Zentralverband Elektrotechnik- und Elektronikindustrie e. V. Batteries Association Lyoner Straße 9 60528 Frankfurt

Tel.: +49 69 6302-283 Fax: +49 69 6302-362 Email: [email protected] www.zvei.org

© ZVEI 2017 In case of doubt the original German version prevails. In spite of all due care, however, we cannot accept any liability that the information is complete or correct or up to date.

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