Battery charging is a process whereby the cell of a battery is recharge to bring it back approximately to its initial stage. Battery can be classified as primary and secondary cells. The chemical in primary is dry cell when it is used up cannot be restored. As the accumulator is being used, discharged take place i.e. the chemical is used up and the E.M.F. and relative density of the cell falls. Charging battery is done by passing a DC through the battery opposite that of discharge. It is necessary to reduce a mean of charging (converting) from AC to DC in a process called rectification. The rectifying circuit is very important in the operation of a battery charger. There are different kinds of battery chargers, constant voltage, constant current, trickle charger and float charger. The best type of battery charger is the trickle charger in which a little current is passed into the battery for a long time.