Abstract: In a secondary battery charging system and charging apparatus, when using either a step-down method or a constant-current/constant-voltage method of charging a secondary battery, a switching regulator is used to vary the charging current supplied to a secondary battery in accordance with the duty cycle of one pulse, so that a voltage that exceeds a pre-established voltage value is not applied to the secondary battery.

Abstract: A high-speed secondary cell charging system is provided which accurately measures the amount of time to achieve a full-charge condition in a secondary cell. In this system, when charging a secondary cell while detecting a charging characteristic of the secondary cell, charging is performed of the secondary cell using a prescribed amount of charging current. Then, when a prescribed condition with regard to the secondary cell is detected, the secondary cell is charged once again, this time with a current that is smaller than the previous charging current. When a condition indicating the completion of the charging of the secondary cell is detected, the charging is stopped. If this condition is not detected, a yet smaller charging current is set and the charging of the secondary cell is performed once again, the above operations being repeated until a condition which indicates that the charging of the secondary cell is complete is detected.