Mainly there are three types of charging of battery.

a. Constant current charging system. 

In this system the charging current is kept to constant by varying the supplied DC voltage by the help of rheostat or filament lamps in series with the battery, so as to over come the increased back emf of the battery or of the cell.

Charging current = V – Eb / R + r amps. 

b. Constant voltage or potential charging. 

In this system the voltage is kept to constant, so the charging current in the beginning will be high when the back emf or counter emf of the battery is low and current will be small when the back or counter emf increases as the battery gets charge. 

c. Trickle charging system. 

The continuous charging of a battery at a very low rate for keeping the battery ready in good working condition is called the trickle charging. This is to maintain the losses occurring at the idle period. The value of the trickle charging current is approximately 2% of the full charging current of the battery