What is the purpose of equalization charge in lead-acid batteries?

The purpose of equalization charge in lead-acid batteries is to reverse the effects of stratification and sulfation, which can reduce battery capacity and lifespan. Over time, during normal charge and discharge cycles, the electrolyte in lead-acid batteries can stratify, meaning the acid concentration becomes higher at the bottom of the battery and lower at the top. This uneven acid distribution reduces the battery's overall efficiency and capacity. Also, lead sulfate crystals can build up on the battery plates, a process known as sulfation. This sulfation reduces the active surface area of the plates and increases the battery's internal resistance, making it harder to charge and discharge. An equalization charge is a controlled overcharge that is applied to the battery for a specific period of time. This overcharge causes gassing within the battery, which mixes the electrolyte and reduces stratification. The higher voltage also helps to break down the lead sulfate crystals, reversing sulfation. However, equalization charging must be done carefully, as excessive overcharging can damage the battery. The voltage and duration of the equalization charge should be in accordance with the battery manufacturer's recommendations. Equalization charging is typically performed periodically, such as once a month or once a quarter, to maintain the battery's performance and extend its lifespan.