SECONDARY BATTERY WITH PROTECTIVE CIRCUIT

A secondary battery 101 of the present invention is comprised such that a heat-sensitive element 133 which varies in resistance value due to change of temperature is not placed on a path through which a charge or discharge current flows into or out of a storage battery device 111. Accordingly, when a main switch element 114 generates heat due to an overcurrent, a change in resistance value of the heat-sensitive element 114 resulting from the heat will allow an auxiliary switch element 122 to be turned ON, thereby causing first and second auxiliary fuse elements 135a and 135b to be blown. The charge or discharge current causes no power consumption at the heat-sensitive element 133, thereby providing high efficiency. The heat-sensitive element 133 can be reduced in current capacity for use and it is suitable for compact design.