Abstract
A low cost battery charger is introduced in this paper. The charging feature meets the requirement of a Li-Ion rechargeable cell designed for electric vehicles and manufactured by E company. The charger is capable of constant current/constant voltage charging strategy, double over current/voltage protection and automatically offloaded with a sound alarm when the charging current is smaller than about 40mA. A detail circuit diagram and its operation principle are proposed and some experimental results are also given. All devices used in the charger circuit are very common and easily purchased. Because of its simple structure only a few modifications are needed to make one’s own specific charger.