Secondary battery charging method and apparatus which controls protecting voltage level of battery protecting circuit

摘要

A secondary battery is connected to a protecting circuit. The protecting circuit interrupts charging of the secondary battery when the battery voltage of the secondary battery reaches a first protecting voltage which is higher than a first voltage, the first voltage being the full charge voltage of the secondary battery. After constant current charging of the secondary battery, the secondary battery is charged until the battery voltage of the secondary battery becomes higher than the first protecting voltage for achieving rapid charging of the secondary battery. When the secondary battery is charged in this condition, the protecting voltage of the protecting circuit is changed over to a second protecting voltage which is higher than the first protecting voltage for this preventing the protecting circuit from operating.