Battery Maintenance


To ensure optimum battery performance and life, it is critical that a thorough care and maintenance program be followed and documented. Midwest Lift Trucks recommends the following procedures and considerations:


  • Under normal circumstances, a battery should be charged when it reaches 80% depth of discharge (near the “red zone” on most discharge meters), not before. If your forklift is not equipped with a battery discharge meter, this is a necessary addition.
  • New batteries are designed to provide 1,500 charge “cycles” or more. If your application is light to medium duty, or sporadic, charge only when necessary rather than daily. It will spread the cycle life of the battery over a much longer period of time, and ensure that you get the maximum number of productive years from your battery.
  • Select “weekend”, “equalize” or “weekly” charge (depending on your brand of charger) every 5 to 10 recharge cycles (no more than weekly, no less than monthly) to keep the battery performing at peak efficiency. Failure to do so, or selecting this option too often, will harm the battery and shorten its effective life.


  • New batteries require water approximately every 10 charges for the first few years. Rebuilt batteries may require water every 5 charges.
  • On both new and rebuilt batteries, check 2 or 3 pilot cells every 5 charges to see that the water level is just above the red perforated splash guard after charging.
  • If the water level is low, add only enough water the cover the splash guard by about ¼". The additional space is necessary for expansion while gassing at the end of the charge. A battery watering adapter kit can greatly ease battery watering.


  • If a battery ever overflows, take a few minutes to rinse it with water immediately afterwards (baking soda optional) to prevent corrosion of top of and beneath the battery. Use enough water to thoroughly dilute the spilled acid to the extent that it is not harmful to the environment.
  • The spilled acid is both highly conductive and corrosive. If not rinsed away, the conductivity can cause the battery to discharge itself, even while not in use, and generate additional damaging heat during recharge.
  • Over time, acid left on top of the battery will form clumps of conductive white corrosion. If it is allowed to accumulate, it can dramatically shorten the life to the battery and make checking and adding water a difficult and unpleasant experience, and an obvious safety hazard, which employees will tend to avoid.
  • Acid vapors escape during charging, and reside will develop around the vent cap area even under normal circumstances. Batteries should be rinsed at least twice per year to remove acid residue form the battery.
  • Consider keeping an acid spill clean up kit near the charging station.


  • Never over fill the battery. It will cause overflow on the next charge. Acid loss shortens the battery run time, generates excess heat, and requires shop service to correct.
  • Never make a habit of giving short charges during breaks in operation. Each short charge constitutes a “cycle” and over time will significantly affect the performance and life of the battery. It also causes excess heat that will make the battery less efficient than not charging at all. It’s much better to let a battery rest and cool during breaks in operation.
  • Never interrupt a charge cycle if possible. Once a charge cycle has been initiated, it should be allowed to complete.
  • Never allow a battery to sit discharged more than a few days to avoid “sulfation”. If it becomes necessary to store a battery for an expended period, charge it prior to storage and once every 3 to 6 months during storage to avoid damage.
  • Never allow a battery to go completely dead (unusable). It will take over 72 hours of continuous charging to bring back to operational charge, and may require shop service to restore full charge.
  • Never continue using an overheating battery. If a battery ever radiates excessive heat during use of charging, or emits a strong sulfur smell, discontinue use and call for service. There is either a battery, charger of forklift problem.
  • Never allow sparks or flame near a charging battery. Batteries produce explosive hydrogen gas while charging, which could cause an explosion resulting in injury or death.


  • Deep discharging will harm the battery and cause all of the forklift’s electrical components to run excessively hot. Significant lift truck damage can result, including complete motor failure, burned armatures and brushes, and burned or stuck contacts. Any of these problems can render the forklift unsafe or unusable.
  • Deep discharge can easily increase the recharge time to outside your charge’s range to recover, causing the battery to be only partially charged.
  • Most automatic chargers must sense a minimum voltage to active and turn on. If the battery is below the threshold voltage, the charger will not be able to recharge the battery and may require a service call to manually start the charger.

The Two Golden Rules for Battery Performance

Maintain the water at the proper level

Always charge on the proper cycle:

Full Charge → Discharge to 20% Remaining Capacity → Full Charge

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