Formation of Bulges in Batteries

Bulging in batteries usually indicates gas formation. Gas formation can occur due to overcharging or due to an internal short circuit in the battery. Short circuit causes arcing which can cause gas formation. Overcharging can be caused by improper battery charger settings which apply current even the battery has become fully charged.

Batteries which have bulges need to be replaced. These batteries  may not charge fully or may not hold charge. If the reason for the battery bulge is found to be overcharging, the charger also needs to be checked and the charge settings changed.