How to Check a Faulty Electric Forklift Battery: A Complete and Accurate Guide

When your forklift battery is faulty – what should you do?

When an electric forklift operates unstably or the battery shows signs of damage, follow a scientific inspection process—from basic to advanced steps. Proper inspection helps detect issues early, extend battery life, and avoid sudden breakdowns.

Here are 7 professional steps to check a faulty forklift battery:

1. Visual Inspection of the Battery

• Battery casing: Check for swelling, cracks, or electrolyte leaks.

• Battery terminals: Look for oxidation, corrosion, or looseness.

• Wires and connectors: Inspect for looseness, burn marks, or broken wires.
  ⚠️ This is a simple but crucial step to ensure safety and good connection.

2. Measure Voltage of Each Cell and the Whole Pack

Use a multimeter to measure:

• Each cell (for open lead-acid batteries)

• Whole pack (for sealed or lithium batteries)

If voltage is lower than standard → the cell may be weak, dead, or unbalanced.
✅ Example: A full 24V battery should measure 25.2V – 26.5V.

3. Check the Charger and Charging Current

• Is the charger working? (LED indicators, fan spinning, current output)

• Is the charging current within specs? Low current → undercharging → battery degradation

• Use a multimeter to measure charger output.

4. Check Battery Temperature During Charging or Operation

• Monitor battery temperature when charging or lifting load

• Unusual heating may be due to:

  • Internal short circuit

  • Overload

  • BMS malfunction

5. Check Electrolyte (for open lead-acid batteries)

• Use a hydrometer to measure acid specific gravity in each cell

• Observe electrolyte color:

  • Dark, sedimented, or discolored → sulfation → major performance drop

6. Check Battery Management System (BMS – for lithium batteries)

• Use software or specialized tools to connect to the BMS

• Check common faults:

  • Weak/unbalanced cells

  • High temperature

  • Circuit interruption

  • Communication errors
    🧑‍💻 Modern lithium batteries usually have built-in BMS that auto shut down on risks—checking BMS is vital.

7. Load Test

• Connect battery to forklift or similar load device

• Monitor voltage during load lifting:

  • Fast voltage drop → may indicate high internal resistance, weak or degraded cells

✅ Conclusion

Regular battery checks are essential, especially when faults arise. Follow these 7 steps to ensure efficient, cost-saving, and safe forklift operation.

For free technical advice, repairs, or genuine battery replacements (lithium or lead-acid), contact a certified battery provider.