Some causes for automobile battery overcharging are mismatched charger for the battery and a high charging rate due to a malfunctioning component. Overcharging can potentially damage the internal structure of the battery.
When a battery is overcharged, gasses within the battery can accumulate and build up pressure, causing it to swell and potentially explode if the battery is ignited by a spark. A typical overcharging error occurs when a charger that is not specifically designed for a particular battery's capacity is used. This incompatibility in capacity can shorten the life of a battery. A faulty voltage regulator can cause extreme charging rates that can also lead to overcharging.