Why does the battery get hot during charging?

[ElisaDella]

There are two situations where a car battery may overheat: one is during discharging, and the other is during charging. The details are as follows: 1. Discharging overheating: When the motor's rated voltage is low, the battery capacity is small, and the operating current is relatively high, the voltage will drop sharply, the capacity will deplete quickly, resulting in battery overheating. 2. Charging overheating: Battery aging, increased internal resistance, dried-up electrolyte, or internal short circuits can cause overheating. As the battery undergoes more charge-discharge cycles, water molecules within the battery gradually deplete, leading to heat generation during electrochemical reactions. Additionally, sulfate crystallization forms during charge-discharge processes, adhering to lead plates as sediment, which increases battery resistance and causes overheating.