Back to Battery Basics: Equalization Charging Keeps Your Lift Truck Running Longer

Forklift Equalization Charging

An electric forklift is as compelling as an alternative to gasoline or liquid petroleum-fueled lift trucks for a variety of reasons, one of which is the simplicity of relying on a battery for power. Batteries are convenient, requiring little extensive maintenance. There are a few operations with which you should be familiar to extend your battery life. One example is Battery watering or maintaining adequate water levels in your battery cells. Another important operation, which we’ll cover in detail here, is equalization charging.

What is Equalization Charging?

Equalization charging is essentially a forced overcharge of the battery that causes gassing and bubbling when the voltage is increased to 110% of the recommended level. The result is that all battery cells are brought to a similar voltage/performance level. Equalization charging is a special step in the battery process intended to mitigate problematic conditions that occur naturally as the battery is used.

  • One of these conditions is called sulfation, or the buildup of lead sulfate on the activating plates inside the battery. Sulfation occurs as sulfuric acid and the leaded plates interact during battery usage. The buildup of lead sulfate on the plates can reduce battery capacity and lifespan, but equalization charging removes the buildup before it crystallizes and hardens.
  • Another condition known as stratification occurs when the acid and water that comprise the battery’s electrolyte mixture separate. The acid sinks to the bottom of the cell, potentially causing damage. By causing gassing and bubbling within the battery’s cells, equalization charging remixes the electrolyte, decreasing stratification.
Recommendations regarding the frequency in which you should apply an equalizing charge to lead-acid batteries can vary from once or twice a month to once or twice a year. In general, the best practice is to consult literature provided by your specific battery manufacturer and abide by that timeline. Regardless of frequency, equalization charging is definitely a good idea.

How is Equalization Charging Performed?

The first step in the battery equalization process is finding a forklift battery charger with the ability to equalize the battery, whether automatically or via manual voltage setting: Not all chargers offer this functionality! Consider this while choosing your charger, while also ensuring the charger and battery are physically compatible and have appropriately matching voltage inputs/outputs. In general, buying batteries and chargers from the same supplier help both with compatibility issue avoidance and with troubleshooting/support, should you need it. Once you have an appropriate charger, equalization charging is fairly straightforward:
  1. Remove all loads from the battery
  2. Connect the charger to the battery
  3. Set the charger for the battery manufacturer-directed equalization charge level
  4. Begin charging, ensuring the electrolyte begins bubbling and gassing
  5. Measure the specific gravity of the cells periodically, as this will increase with charging
  6. Finished when specific gravity no longer increases; be vigilant
  7. Replace any water lost during the charging process (see our battery watering post for details)
A Final Note on Safety While convenient, batteries still require careful handling to avoid injury or damage. Even though they don’t derive power from flammable liquids, lead-acid batteries still exude hydrogen gas during charging (which causes the bubbling), and the cells fill with caustic acid. Always ensure proper ventilation while charging to avoid explosion risks, and avoid allowing acid to escape cells by not overfilling or mishandling the battery. Follow these proper safety protocols, and your batteries will be safe and reliable sources of energy for your lift trucks. Extending the life of your lift truck battery could be as simple as applying periodic equalization charges. Have questions on this or any other forklift-related topic? Contact us today or call at 614-986-2360  

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