Battery (All): Terminology: Sulfation

Sulfation is where, in some circumstances, large insoluble lead sulphate crystals are formed on the plates as the battery discharges. This reduces the capacity of the battery. Note that the formation of small soluble lead sulphate crystals is normal during discharge.

The plates always expand during discharge. If the discharge is very slow, the expansion may be so great that the plates deform or crack. Such damage is permanent and the battery must be discarded. This is an excessive form of sulfation. The longer the sulfation process continues, the more difficult it is to save the battery.

Sulfation is a result of a battery being left standing for a long period at a low charge, or the battery has been under charged repeatedly. Regular charging of the battery will prevent sulfation.