Industrial Battery Care for your Electric Forklift

This article will focus on lead-acid plate industrial batteries for use in electric forklifts. These battery care topics do not apply to Lithium-Ion Power, Hydrogen Fuel Cells, Gel Cell Batteries or AGM – Absorbed Glass Mat Batteries. The advantages of the lead-acid plate battery we will be discussing include it is an affordable power source and the technology is long tested tried and reliable and is capable of high discharge rates. A typical scenario for battery care would be the forklift operator charges and waters the battery. An in-house maintenance technician would then be responsible for periodic battery and charger inspections, minor maintenance such as checking the electrolyte level and voltage of each cell of battery before a charge cycle with a hydrometer and record the specific gravity and voltage.

Care should be taken to assure that vent caps are functioning. The battery (or compartment) cover(s) should be open to dissipate heat. Since the caps are vented there is no need to remove caps during charging unless you have old non-vented caps. Then an in-house maintenance technician would identify more advanced maintenance issues which need to be addressed by a fully trained industrial battery service technician. These services include advanced testing with such tools as load banks, continuous chargers, and data collectors. These tests may lead to the need to re-training operators in proper charging practices, changing out battery cells, battery washing, intercell connector replacement, cable and connector replacement, and data collection and analysis of run-time and charging issues. Of course, these duties may be delegated differently at your warehouse or plant. It is important that whoever is responsible for each of the above tasks the responsible people must be properly trained in performing the tasks they are assigned. Industrial batteries are marvelous tools, but we must handle them with care to minimize the hazards inherent with using these batteries.

Proper charging practices require 8 hours of charge followed by 8 hours cool down time followed by using the battery to a state of discharge near below 40% state of charge but not below 20%. Temperature is the enemy of batteries. That is why cooling after charging is critical. A charging environment of 77° F is ideal for charging. The hotter the environment the battery works in the lower the life span of the battery. The temperature of the battery itself during charging and discharge will vary from -4°F to 122°F. Again, temperatures outside this range will shorten the life cycle of the battery. If you are interested in opportunity charging or fast charging, you will need to consult with your supplier as different equipment will be necessary to take advantage of these technologies.

The only time you should add water to your battery is right after charging. If you make the mistake of adding water before charging, the electrolyte solution in your battery will overflow out of the battery cell vent caps. The electrolyte solution consists of 37.52% concentration of concentrated 98% grade sulfuric acid to water: Battery acid. 1.285 specific gravity. During normal charging water vapor and hydrogen gas will “gas” out of the cell vent caps. Adding water back to the cell brings the electrolyte back to the proper concentration. However, if you improperly charge your battery right before charging and electrolyte boils out of the vent caps then adding only water back to the cells will not restore the proper concentration and a battery maintenance professional will need to add additional sulfuric acid to correct this condition. The outside of your battery will, also, require cleaning. Batteries will and should produce gas (i.e. boil) while charging and while discharging. Therefore, you need to water the batteries regularly. This boiling and gassing typically occur during the last three hours of the regular 8-hour cycle charge. You must set up your charging area in a properly ventilated area so the odorous fumes are adequately dispersed.

Recommended Charging Procedures Practices:

      • Take electric forklift to designated well-ventilated charging area and unplug the battery from the electric forklift.
      • Put on personal protective equipment PPE such as face shield, safety goggles, neoprene or rubber gloves and apron.
      • Check the water level prior to charging, but do not add water until full charge cycle is complete.
      • Plug Charger into the battery. Take care to plug the charger into the battery, not to your forklift. You want to charge your battery not damage the electrical components in your forklift.
      • Follow the manufacturers’ instructions for charger settings. Many chargers are automatic, but you may need to set a timer on some chargers.
      • If the battery gets too hot or you notice electrolyte coming out of the vents, turn off the charger. Ask maintenance for assistance in checking the battery and charger and then charging will be restarted at a lower charging rate.
      • After charging is complete unplug the charger from the battery and check water level again. Add distilled or de-ionized water if the water level is low. You will add water to ¼” above the plates.
      • Plug Battery back into the electric forklift and return to service.
      • If you did remove the battery from the truck, then you would reinstall the battery in to truck with lifting beam and secure in place and then plug the battery back into the truck.
      • Check the electric forklift’s Battery Discharge Indicator to verify it reads as fully charged.

Other recommended charging practices include

      • Follow your plant’s specific safety rules.
      • Follow charger battery and forklift manufacturers’ guides.
      • Properly position electric forklift and apply brakes and turn truck off prior to charging.
      • Use a proper lifting beam when removing the battery from an electric forklift. Do use a chain with two hooks as this creates undue stresses on the battery case and can cause internal damage to the battery.
      • Charging area should have eyewash station, an acid spill kit and a fire extinguisher nearby.
      • When charging batteries, pour acid into water. Never pour water into acid.
      • Signs should be clearly posted prohibiting smoking in the charging area.
      • Take precautions to prevent open flames, sparks, or electric arcs in battery charging areas.
      • Remove all metallic jewelry before recharging. Tools and other metallic objects shall be kept away from the top of uncovered batteries.


After charging is complete check the fluid levels in each battery cell. Add water to cells as required. Add distilled water to any cells in which the level of electrolyte isn’t touching the bottom of the fill port. This would be ¼” above the plates. Use only distilled water. The minerals in tap water will eventually reduce a battery’s capacity. If your battery is one of the so-called low-maintenance varieties, you may not see any filler caps. De-ionized water may be used instead of distilled water. If you notice a strong sulfide odor during or after charging, you may have a cell which has failed or it may just be wet corrosion products left on top of the battery or between the cells. Have a trained battery technician evaluate your battery. To avoid the task of checking the fluid level in each cell after charging and the messy process of watering the cells by hand you may install a Fluid level indicator also known as a “Blinky” and a watering system.



It is important that your charger is properly sized to your battery. If it is not, you may not achieve gassing and the chemical process in your battery cells will be incomplete. This will shorten the life cycle of your battery. It is equally important to ensure your battery is properly sized to your forklift and your application. Your battery must meet the truck minimum battery weight as this is often part of the counterbalance weight designed into your forklift. Also, properly specifying your battery will provide the run time you expect and protect the electrical components of your lift truck. The data plates on your forklift, battery and charger are great sources of information. If your battery is missing a data plate or it can no longer be read, then you can find vital battery information stamped on the battery inter-cell connectors near the positive cable post-termination.

Typically, you want to equalize charge your battery once a week. This is usually done over the weekend. You will usually find an equalize charge setting on your charger. This setting charges your battery for 11 hours. The final 3 hours at a very low rate of charge. This allows for slightly weaker cells to get the extra charge they require. Equalize charging will extend the life of your battery.

Battery Charging Safety Checklist

    • Keep sparks, flames, burning cigarettes, and other ignition sources away.
    • Be sure the room is properly ventilated.
    • Always wear personal protective equipment (PPE) such as safety goggles or full-face shield, gloves, and rubber apron.
    • If acid splashes into eyes, flush immediately with cold water. You will need an eye washing station near the battery maintenance and charging area which may be eyewash bottles, a plumbed in eyewash station or a plumbed eyewash station with a full shower. Keep in mind that the water being delivered must always be at ambient temperature for the safety of the injured. These eyewash stations must be inspected for readiness periodically.
    • Do not attempt to charge batteries unless you are properly trained.
    • Shut off the charger before connecting or disconnecting the battery
    • Keep charger cables off the floor
    • Keep a proper Acid spill kit on hand to neutralize any spills and make sure you have baking soda on hand to help with this process.

Be mindful not to do the activities in this list:

    • Do not keep the industrial battery in direct sunlight, dust or moist place.
    • Do not add any acid or DM water in case of SMF battery.
    • Do not tamper the vent plugs.
    • Do not over tight/under tight the terminal bolts which may cause terminal breakage or fire due to loose contact.
    • Do not allow any metal object to rest on the battery – this may cause a short circuit.
    • Do not mix with different capacities, types (VRLA, Flooded/ Tubular batteries) and manufacturers’ batteries in the same circuit.
    • No cell tapping will be allowed during the service life.
    • Do not use underrating cables for connecting the battery.
    • Never install any type of battery in a completely sealed container. Sufficient ventilation to be provided for air circulation.
    • Do not allow discharged battery for more than 12 hours in idle condition.
    • Do not deep discharge the battery below specified limits.

If you are unsure of the amp hours or kWh of your battery, you can calculate these numbers by counting the cells in the battery case, knowing the ampere-hour of each positive plate and the total number of plates. The model will generally give you this information. The model of the battery looks something like 12-110-15. In this example we can determine based on the model number:

  • 12 = the number of cells, verify this by counting the cells in your battery
  • 12 x 2 volts per cell = 24 volt battery
  • 110 = plate capacity in ampere-hours for each positive plate
  • 15 = total number of plates
  • The output amp hours of the battery are calculated as follows:
    • 15-1=14
    • 14/2 = 7
    • 7 x 110 = 770 AH
  • The KWH output is calculated as follows:
    • 770 AH x 24 volts = 18,480
    • 18,480 ÷ 1,000 = 18.48
    • 18.48 x .97 = 17.9256 kWh (Kilowatt Hour)
    • The kWh (Kilowatt Hour) – is a good way to compare batteries to other batteries. The higher the kWh of a battery the more power it will be able to deliver.

Use this information to improve your battery care practices. This will go a long way towards maximizing your battery run time and overall life.

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