If a battery is charged at an excessive voltage or current, it can overheat, and the electrolyte will start to evaporate. Overcharging will cause the active mass in the plates of the battery to rapidly breakup, and battery performance will be permanently affected, as will the cyclic life of the battery. This is normally quite obvious to spot when examining the battery. This is not a manufacturing fault.

Sulphation occurs when a battery is allowed to stand in a discharged state for an excessive amount of time. When a battery voltage drops below a certain level, a chemical reaction known as sulphation takes place. In most cases this voltage is at or below 12.06v. Sulphation is normally irreversible, and can permanently impair performance of the battery, causing reduced performance and premature failure. Sulphation can be seen as a fine white/grey coating on the plates.

This damage can be caused if a battery is stored for long periods without charging, or installed in applications that are not frequently used. Over time, sulphation will build up on the plates, and hinder the performance of the battery. As sulphation is easily avoided by simply keeping your battery charged, this is a non-manufacturing fault.