Device and method for controlled charging of a secondary battery
A device and method is provided that can detect overcharge reliably by separating heat generated by internal resistance and heat chemically generated upon overcharging in a secondary battery. Based on the temperature of the secondary battery (10) detected every first predetermined time by a battery temperature detection section (12), a temperature gradient operation section (14) calculates a temperature gradient indicating a temperature increase per unit time for every second predetermined time that is longer than the first predetermined time. When a temperature gradient determination section (16) determines that the temperature gradient is larger than a predetermined temperature gradient threshold, which is preset according to the charged state of the secondary battery,  N  times in a row (where  N  is a natural number), a fully charged state of the secondary battery is detected.