Patent ID: 6917505
Filing Date: 2005-07-12
Classification: H01H,H01M,H02H,Y02E

Abstract:
1. A secondary battery comprising an accumulator, a protective circuit and external connection terminals; wherein the protective circuit includes a heater that generates heat when a voltage is applied, a main fuse connected in series with the heater, so that the main fuse is heated by the heater and breaks at a specified blowout temperature, and a thermistor connected in parallel with the heater and having a resistance value that is increased by heating; wherein when the external connection terminals are connected to a DC voltage source, a current supplied from the DC voltage source charges the accumulator through the protective circuit, and when the external connection terminals are connected to an electronic apparatus, a current discharged from the accumulator is supplied to the electronic apparatus through the protective circuit; and wherein the main fuse does not reach the blowout temperature under the current passing through the protective circuit when the external connection terminals are short-circuited, but the main fuse heats up to or above the blowout temperature when the external connection terminals are connected to a voltage source 1.5 times or more the rated charging voltage of the accumulator, provided that the accumulator is not charged to the full charge voltage.