How to handle battery swelling during equalization charging?

Understanding Battery Swelling

Battery swelling occurs when the electrolyte in lead-acid batteries gasses off during charging, causing the battery case to expand. This can be exacerbated during equalization charging, which involves intentionally overcharging the battery to balance the cells. Equalization charging can help to equalize the state of charge in the cells, but it can also lead to overcharging and subsequent swelling.

Preventing Damage During Equalization

To prevent damage during equalization, it is essential to disconnect the batteries from the charging source and allow them to cool down. This will help to prevent the buildup of excessive heat, which can accelerate the gassing reaction and lead to further swelling. It is also crucial to use a gentle equalization charge with a lower voltage and current. A good rule of thumb is to reduce the voltage by 0.1-0.2 volts and the current by 50-75% compared to the normal charging voltage and current. For example, if the normal charging voltage is 14.4 volts, the equalization voltage might be 14.2-14.0 volts.

Equalization Techniques

Equalization is typically performed at a lower voltage than normal charging to prevent excessive gassing and swelling. A good equalization technique is to charge the batteries at a voltage of 13.2-13.5 volts for a period of 2-4 hours. This will allow the batteries to equalize and balance, while minimizing the risk of damage due to excessive swelling. It is also essential to monitor the batteries during equalization and adjust the voltage and current as needed to prevent excessive gassing and swelling.