In Brief
A traction battery is selected by voltage (most commonly 24V, 48V, or 80V for lifting equipment), capacity in ampere-hours according to the duration of the shift, and overall dimensions that must match the battery compartment in the machine. The construction family affects performance, maintenance, and price. The voltage is read from the machine’s nameplate, while the dimensions are measured at the battery compartment.
Contents
- What is a traction battery and how does it differ from a starter battery
- How to determine the battery voltage for your machine
- Why overall dimensions matter as much as voltage
- How to read a traction battery designation
- What ampere-hour capacity do you need
- PzS, PzB, PzSL or PzSH: how to choose the construction
- Battery for a stacker, forklift, and pallet truck
- Battery for Linde, Still, Jungheinrich, and other brands
- When does it make sense to switch to a lithium-ion battery
- Industrial batteries beyond lifting equipment
- How to choose a charger for the battery voltage
- Five common mistakes when choosing
- Frequently Asked Questions
What is a traction battery and how does it differ from a starter battery
A traction battery is a rechargeable battery designed to deliver a relatively moderate current for a long period and withstand repeated deep discharge. A car starter battery is designed for the opposite: a very high current for a few seconds and shallow discharge.
The difference is structural. PzS and PzB traction cells use tubular positive plates that withstand cyclic discharge, while starter batteries have thin grid plates with a large surface area. Therefore, a starter battery installed in an electric forklift is destroyed in a short time, while a traction battery in a car cannot provide the required starting current.
For this reason, the service life of traction batteries is usually assessed in operating cycles, not only in years. Lead-acid traction batteries for electric forklifts and stackers from the POLIBET-EXPORT range last up to 1,500 operating cycles according to the catalogue.
How to determine the battery voltage for your machine
Voltage is not selected – it is dictated by the machine and cannot be changed. Installing a battery with a different voltage can damage the control system and drive.
Where to find the voltage
Check these three places in sequence:
- The machine nameplate, where the battery’s nominal voltage is usually indicated.
- The battery itself, which has a designation such as 48V 4PzS 500.
- The technical documentation or catalogue sheet for the model.
For lead-acid batteries, the voltage can also be checked by the number of cells: each cell has a nominal voltage of 2V. A battery with 12 cells is 24V, with 24 cells is 48V, and with 40 cells is 80V.
12V and 6V Batteries
12V traction batteries are used in smaller warehouse equipment and machines whose electrical systems are designed for 12V. In the catalogue, 12V is offered in PzSL construction – for example, 2PzSL 160Ah and 6PzSL 660Ah. The range of ELT 6V – 12V lead-acid semi-traction batteries is also available separately, covering applications with a lighter cyclic operating mode.
24V Batteries
24V is commonly found in stackers, pallet trucks, and smaller electric forklifts. This voltage has broad coverage in the catalogue, including numerous PzB, PzSL, and PzSH configurations in the range from 150Ah to 1120Ah. For PzS, the specific capacity should be checked according to the model.
48V Batteries
48V is widely used in electric forklifts with medium lifting capacities. This voltage covers both single-shift machines and machines operating intensive multi-shift schedules, so the choice of construction and capacity requires more careful consideration.
80V Batteries
80V is generally used in heavier electric forklifts and machines with high lifting capacities. Batteries at this voltage are heavier and more expensive, while the battery compartment is larger, often leaving less flexibility when selecting an alternative configuration.
36V, 40V, and 72V Voltages
These voltages are found in more specific machines and older equipment. The catalogue includes 36V, 40V, and 72V configurations in PzSL and PzSH construction. If your machine uses one of these voltages, state it explicitly when making an enquiry so that the appropriate configuration and current availability can be checked.
Why overall dimensions matter as much as voltage
Overall dimensions determine whether the battery can be installed at all. Two batteries with the same voltage and capacity can have completely different dimensions because the cells are arranged differently.
Which three dimensions are measured
Measure the battery compartment in millimetres:
- Length – in the direction in which the battery is removed.
- Width – across the direction in which the battery is removed.
- Height – from the bottom of the compartment to the upper edge, taking into account the space required for caps and cables.
Measure the compartment rather than the old battery if the old battery is deformed. There should be a suitable technical clearance between the battery and the compartment walls, but excessive clearance allows the battery to move during operation.
Terminal and cable position
In addition to the dimensions, note the terminal type, cable length, and the side from which it exits. A battery with the correct dimensions but a terminal on the wrong side cannot be connected without modification.
Weight and counterweight
In electric forklifts, the battery weight forms part of the machine’s counterweight. The manufacturer specifies the minimum and maximum permissible battery weight, and these limits must be observed because stability and the stated lifting capacity depend on it.
This is a safety issue, not a matter of convenience. A battery below the minimum permissible weight should not be installed without an explicit statement from the machine manufacturer. PolyBat lithium-ion batteries are described in the catalogue as matching the dimensions and weight of the lead-acid batteries they replace, but compatibility must be confirmed for the specific configuration. When a lithium pack is lighter than required, the difference is compensated with ballast at the decision of the manufacturer or an authorised service centre.
How to read a traction battery designation
A designation such as 24V 4PzB 300 contains four pieces of information. Decoding it eliminates half the work involved in choosing.
| Part of the designation | What it means | Example |
|---|---|---|
| 24V | nominal battery voltage | 24V, 48V, 80V |
| 4 | number of positive plates in the cell | 2, 3, 4, 5, 7, 8 |
| PzB | cell construction family | PzS, PzB, PzSL, PzSH |
| 300 | nominal capacity in ampere-hours | 150Ah, 300Ah, 500Ah |
The capacity per plate depends on the family. In the POLIBET-EXPORT catalogue, the ratio for the PzB family is constant: 2PzB is 150Ah, 3PzB is 225Ah, 4PzB is 300Ah, 5PzB is 375Ah, and 7PzB is 525Ah, i.e. 75Ah per positive plate. For the PzSL family, the ratio varies between individual models, so the capacity should be read from the table rather than calculated.
What ampere-hour capacity do you need
The required capacity is determined by the machine’s consumption and the duration of the shift, not by the highest available figure in the catalogue. A larger battery means more weight, larger dimensions, and a higher price.
The practical approach is as follows:
- Check what capacity was previously installed and whether it lasted until the end of the shift.
- If the battery lasted with reserve, the same capacity is sufficient.
- If the machine stopped before the end of the shift, determine whether the cause was insufficient capacity or a worn battery. A worn battery with reduced remaining capacity can create the impression that the nominally selected capacity is insufficient.
- If the operating mode changes – a new shift, heavier loads, longer routes – allow for a reserve.
Deep discharge to complete depletion shortens the life of every traction battery. Additional practical criteria are collected in the article 5 tips for choosing traction batteries.
PzS, PzB, PzSL or PzSH: how to choose the construction
The construction family is selected according to the machine parameters, operating mode, and available catalogue specifications. For PzSL and PzSH, the choice must be confirmed for the specific model because the catalogue does not explicitly describe the operating mode for which each of the two families is intended.
When PzS is suitable
PzS traction cells and batteries are offered in the catalogue with capacities from 100Ah to 1250Ah, as 2V cells and as batteries from 12V to 96V. According to the catalogue, they withstand up to 1,500 operating cycles and are characterised by low water consumption. They are suitable for intensive operation in warehouse equipment.
When PzB is suitable
PzB traction cells and batteries are described in the catalogue as being developed for demanding operating conditions. According to the catalogue, they withstand up to 1,500 operating cycles, offer automatic water-filling capability, and have an efficient ventilation system with additional protection for the internal components.
The difference between PzSL and PzSH
PzSL and PzSH are two separate construction families whose prices do not follow capacity linearly. Example from the catalogue: 48V 5PzSL 400Ah costs EUR 2,086, while 48V 3PzSH 375Ah costs EUR 1,991, meaning that the cheaper option also has a lower capacity. The catalogue does not explicitly describe the load operating mode for which each family is intended, so the choice should not be based on price alone – clarify the matter with the supplier according to your daily operating cycle.
PzSL is offered in the catalogue at 12V, 24V, 36V, 40V, 48V, 72V, and 80V. PzSH is offered at 24V, 36V, 48V, 72V, and 80V.
With the same number of positive plates, there is no universal relationship between PzSL and PzSH. For example, 24V 2PzSL is 180Ah versus 210Ah for 2PzSH, while 48V 8PzSL is 1120Ah versus 1000Ah for 8PzSH. Therefore, the comparison should be made by specific model, not only by the number of plates.
The manufacturer Elhim-Iskra states certified management systems according to ISO 9001 and ISO 45001. These are standards for quality management and occupational health and safety management systems, not technical product standards for the battery itself. Compliance with a specific DIN or British Standard must be checked for the specific model when you require compatibility with a battery factory-installed in a machine from a European manufacturer.
Battery for a stacker, forklift, and pallet truck
Different machines place different requirements on the battery, even when the voltage is the same.
Stacker
Stackers operate with frequent short lifting and travel cycles over relatively short distances. They are often 24V and have a more compact battery compartment, making dimensions a frequent limiting factor. Specific issues concerning this equipment are covered in the article Batteries for stackers.
Electric forklift
In electric forklifts, the battery is also part of the counterweight, so weight is a limiting factor just like dimensions. The voltages here are 24V, 48V, and 80V depending on the model, lifting capacity, and machine configuration. What to check before purchase is described in the article Forklift batteries – before we buy.
Pallet Truck
Pallet trucks generally operate with smaller capacities than electric forklifts, but the specific requirement depends on the model, lifting height, and operating mode. The most common voltage is 24V, while smaller models also use 12V.
Reach Truck
For reach trucks, the operating mode often involves a high frequency of lifting and travel in a warehouse environment. During intensive operation, the time available for battery changes and charging is an important factor, so capacity and the possibility of opportunity charging should be assessed according to the specific operating cycle.
Battery for Linde, Still, Jungheinrich, and other brands
Compatibility is established based on a whole set of parameters, not only the brand name. The machine brand and model are an essential starting point because they determine the specification, but they are not sufficient on their own: the same Linde, Still, or Jungheinrich model may have been supplied with different battery configurations depending on the year, version, and options.
What must be checked
- Machine brand, model, serial number, and year.
- Nominal battery voltage.
- Overall dimensions of the battery compartment: length, width, and height in millimetres.
- Minimum and maximum permissible battery weight according to the machine manufacturer’s data.
- Connector type, cable cross-section and length, and exit side.
- The existing charger and whether it is compatible with the new battery.
Additional checks when switching to a lithium-ion battery
When replacing a lead-acid battery with a lithium-ion battery, communication between the battery management system and the machine must also be checked. On some modern equipment, the control system expects specific signals for state of charge and errors, and on some models this is done via a CAN bus. If this compatibility is not provided, the machine may display errors or limit functions even when the battery itself is operating correctly.
For this reason, the lithium retrofit should be planned together with the battery supplier and, when necessary, with an authorised machine service centre. The enquiry forms on POLIBET-EXPORT product pages require voltage, desired capacity, and overall dimensions, but in a more complex case it is faster to contact the team in Kazanlak directly with the full list of data above.
When does it make sense to switch to a lithium-ion battery
Switching to a lithium-ion battery can make sense for multi-shift operation with short breaks and for heavily used machines, but the suitability also depends on price, charging infrastructure, and the period of use. The main advantage is opportunity charging during breaks: PolyBat lithium-ion batteries for lifting equipment can be charged in 1 to 3 hours depending on capacity, current, and charging method.
What changes with lithium-ion technology
- Electrolyte topping-up and the regular maintenance associated with it are eliminated.
- Opportunity charging during breaks can reduce or, in certain operating modes, eliminate the need for a second battery for replacement. Whether this is achievable depends on the work schedule, capacity, and charger.
- Charging area requirements change because lithium-ion batteries do not release gases during charging like flooded lead-acid batteries. The specific requirements for the premises are assessed for each site.
What should be checked before switching
- Weight and dimensions. PolyBat batteries are described in the catalogue as matching the dimensions and weight of the lead-acid batteries they replace, but this must be confirmed for the specific configuration against the permissible weight specified by the machine manufacturer.
- Compatibility with the machine control system, including communication with the battery management system.
- The charger. Chargers offered by POLIBET-EXPORT are recommended because they are programmed for PolyBat batteries.
- Temperature range. The optimal range is from -5°C to +25°C, while operation above 45°C or below -20°C reduces efficiency and accelerates wear.
PolyBat lithium-ion batteries are offered with a 3-year or 6,000 operating-hour warranty, with the option to extend it to 6 years or 10,000 operating hours.
If you are not sure which configuration you need, the battery rental service can be a temporary option depending on the available parameters and the conditions of the specific offer.
Industrial batteries beyond lifting equipment
The principle of selecting by voltage, capacity, and dimensions also applies to applications outside warehouse equipment, but the additional requirements are different.
Railway Transport
For locomotives and passenger coaches, the battery powers systems where failure has safety implications. POLIBET-EXPORT offers lead-acid batteries for railway transport, including battery packs for passenger coaches manufactured in Bulgaria. The specifics of this equipment are covered in the article Locomotive batteries – types and maintenance.
Stationary Batteries
In backup and UPS applications, stationary OPzS batteries usually operate in buffer mode: they remain charged most of the time and are discharged only when the main power supply fails. In such a mode, the key criterion is not the number of cycles but reliability during long periods in a charged state. Stationary OPzS batteries are intended for backup power systems and UPS applications.
Solar Batteries
In photovoltaic systems, the battery operating profile is determined by the system design – by the relationship between generated energy, consumption, and the capacity of the battery bank. Therefore, the selection criteria differ from those for lifting equipment and are derived from the project rather than from an analogy with traction batteries. ES OPzS solar batteries are part of the stationary and solar battery range.
How to choose a charger for the battery voltage
The charger is selected according to the battery voltage, capacity, and chemistry type, not according to the power rating of the electrical outlet. An unsuitable charger shortens battery life even when everything else has been selected correctly.
Transformer Chargers
Transformer chargers are a proven solution for standard operating modes and lead-acid traction batteries with a predictable daily cycle.
Single-phase and three-phase inverter chargers
Single-phase and three-phase inverter chargers provide more precise control of the charging characteristic. The choice between single-phase and three-phase versions depends on the available power supply at the site, which should be checked in advance.
Charging current for lithium-ion batteries
For PolyBat batteries, the recommended charging current is 0.5C, i.e. a current equal to 50 percent of the nominal capacity. The full range is available in the section chargers for industrial batteries.
Five common mistakes when choosing
- Choosing based only on price. Two batteries with the same electrical parameters may belong to different construction families with different characteristics and different maintenance requirements.
- Ignoring dimensions. The battery is ordered by voltage and capacity, but upon delivery it turns out that it does not fit into the compartment or the terminal is on the other side.
- Ignoring the permissible weight for an electric forklift. A battery outside the range specified by the manufacturer changes the machine balance and affects the stated lifting capacity. This is a safety issue and should be agreed with the manufacturer or an authorised service centre.
- Using the old charger for a new battery with different chemistry. The old charger should not be used with a lithium-ion battery unless the manufacturer or supplier has explicitly confirmed compatibility and the appropriate charging profile.
- Assessing the requirement based on a worn battery. If the old battery has reduced capacity, it is not a good starting point for determining what capacity is actually required.
Frequently Asked Questions
How can I find out what voltage my electric forklift battery has?
Check the machine nameplate, where the battery’s nominal voltage is usually indicated. If the nameplate is missing, count the cells in the existing battery and multiply by 2V – each lead-acid cell has a nominal voltage of 2V. Twelve cells mean 24V, while twenty-four cells mean 48V.
Can I install a battery with a higher capacity than the original?
This is possible only if the new battery fits within the dimensions of the compartment and its weight remains within the range specified by the machine manufacturer. Higher capacity usually means more or larger plates, which means larger dimensions and greater weight. Agree on the change with the supplier and, if in doubt, with an authorised service centre before ordering.
What does 4PzS 500 mean in a battery designation?
The number 4 indicates the number of positive plates in the cell, PzS is the construction family with tubular positive plates, and 500 is the nominal capacity in ampere-hours. The battery voltage usually also appears before the designation, for example 48V 4PzS 500.
What is the difference between a traction and a semi-traction battery?
Traction batteries are designed for deep cyclic discharge during intensive operation of lifting equipment. Semi-traction batteries, such as the ELT 6V – 12V range, are intended for applications with a lighter cyclic operating mode, where discharge is not as deep or as frequent.
Is a traction battery suitable for a solar system?
Usually, it is not the first choice. Traction batteries are designed for the operating conditions of lifting equipment, while in a photovoltaic system the battery operating profile is determined by the system design and the selection criteria are different. For such applications, ES OPzS solar batteries are used, while stationary OPzS batteries are used for backup power. The selection is based on the system design data.
How long does it take to charge a traction battery?
For PolyBat lithium-ion batteries, charging takes 1 to 3 hours depending on capacity, charging current, and charging method. For lead-acid traction batteries, the cycle is significantly longer and time for cooling must be added before the battery can be loaded again.