Treating Sulfated Forklift Batteries

Careful attention to the following steps often will restore a sulfated battery to good operating condition.

  1. Thoroughly clean the battery. (See “Cleaning Your Forklift Battery and Compartment” for details.)
  2. Bring the electrolyte level to proper height by adding water. (See “Watering Your Forklift Battery” for details.)
  3. Put the battery on charge at the prescribed finishing rate or less until the rated AH capacity has been returned to the battery. Record the voltage and specific gravity. Correct the specific gravity readings using the chart shown on page 20. If temperature at any time during these procedures exceeds 115°F, stop the charger and allow the battery to cool to 90°F or below before continuing the charge. Continue charging the battery until the specific gravity, corrected for temperature, shows no change during a four-hour period, taking hourly readings. With automatic charging equipment, the battery may have to be placed on equalizing charge two or three times. If a battery is badly sulfated, the specific gravity may rise only 30 or 40 points (.030 to .040) during this first charge.
  4. Place the battery into service and discharge it to a fully discharged condition
  5. Charge the battery again until the specific gravity shows no change during a four-hour period.
  6. Repeat the charge/discharge process until the specific gravity rises to within 30 points of a fully charged battery. Then place the battery back into normal service.

Although the specific gravities may be lower than normal, they should not vary much from cell to cell. If they do, problems other than sulfation may be present. If the spread between the highest and lowest specific gravity readings is 50 points (.050) or more, call Forklift Express to analyze your battery. If the battery has not responded to the above treatment, it should be replaced. The final specific gravity of a battery depends upon depth of discharge, temperature, its initial specific gravity, and battery type. If you have questions, please call Forklift Express at 770-662-8805.