If a battery is allowed to stand in a discharged state either on or off a vehicle for a period of time, a chemical reaction takes place which will permanently impair the performance and life of the battery, this process is called “sulphation”.
Sulphation can be seen as a fine white/grey coating on the positive plate and a non metallic luster on the negative plate. In most cases this signifies the battery as not serviceable. Attempts to recharge batteries left in a discharged state, even at very low charge rates will lead to damage to the grid and active material interfaces and also sulphate deposits can be formed within the separators which produce dendritic shorts.
The damage can occur in storage or if the battery is installed on the vehicle (or equipment) that is not used for a period of time, for example tractor, motorcycle, boat, airport vehicle even a car or truck that is stored with the battery connected can still damage the battery. This is because there is a permanent drain on the battery from items such as the alarm, clock, lights, etc left on which drag the battery down to its lowest possible state of charge. The longer the period left, the greater the sulphation builds up on the plates.
The sulphation hinders the efficiency of the electrochemical reactions within the battery between the active material of the plates and the acid.
Please kindly note this is not a manufacturing fault.