BATTERY SYSTEM

摘要

Disclosed is a battery system in which overcharging during charging can be prevented, and in which appropriate charging performance and output performance of a secondary battery can be demonstrated even when the battery system is employed in a low-temperature environment. The battery system includes a secondary battery and a protection circuit. The protection circuit is provided with a bypass circuit which links an upstream-side main circuit connected to the positive terminal of the secondary battery and a downstream-side main circuit connected to the negative terminal side. The system is constructed so that, if the voltage of the secondary battery becomes higher than a prescribed voltage during charging, the current flowing through the secondary battery is reduced and the current flowing through the bypass circuit is increased, and if the voltage of the secondary battery becomes lower than a prescribed voltage during charging,the current flowing through the secondary battery is increased andthe current flowing through the bypass circuit is reduced. The bypass circuit is provided with a heater which generates heat from current flowing through the bypass circuit, and the heater is arranged close to or in contact with the secondary battery so as to subject the secondary battery to the effect of heat.