PURPOSE: To preferably quickly charge a battery by repeatedly charging and discharging the cooled battery, then shifting it to a large current-charging, switching to a small current charging if the voltage starts abruptly rising, pausing the charging at the peak voltage point, and setting an additional charging time by a timer.

CONSTITUTION: When a start switch is closed, the temperature of a battery is detected by a temperature sensor. When it is lower than an ambient temperature, a temperature rising circuit is operated, discharging by a discharging circuit and charging by a constant-current circuit are repeated to raise the temperature to the ambient temperature. When the sensor detects that the temperature becomes the ambient temperature, it is charged by a large current set by a constant-current setter. If the temperature starts quickly rising to become a predetermined voltage, it is charged by the normal charging current set by the constant-current setter. When the voltage arrives at a peak, a delta peak detector detects it, and when the battery temperature is higher than the ambient temperature, the charging is temporarily stopped. Then, when the temperature falls, the time of the additional charging is set by a timer, and the charging is conducted. In this manner, it can prevent it from overcharging and quickly charge it.