A chemical reaction in which metal is decomposed, in batteries an undesirable aging process.
Corroded battery terminals, battery clips and terminal adapters conduct the current only very poorly or not at all. To avoid battery failure, it makes sense to check the terminals regularly and remove any corrosion that may occur.
Also the grids of the positive plate in a battery can corrode and even break. This usually happens when the charging voltage is too high, when the temperature is too high, when the acid density is too high, or when there is acid stratification.