BATTERY PACK

PROBLEM TO BE SOLVED: To install, within a battery pack, a self-reset protection circuit for protecting unit cells by means of a temperature control as a system separate from a voltage control. when an abnormal temperature is reached due to overcharging overdischarging or the like. SOLUTION: This battery pack includes a control means 2 having an overcurrent detecting function for detecting an overcurrent flowing through a charging/discharging line, a first switch means 5 for opening/closing the charging/discharging line according to an output signal from the control means 2, a temperature detection means 3 including a non-linear temperature element disposed in contact with a secondary battery or disposed near the secondary battery, and a second switch means 4 opening/closing according to an output signal from the temperature detection means 3, and this battery pack is characterized in that, when the temperature of the secondary battery has risen beyond a fixed temperature, the second switch means 4 closes according to a signal from the temperature detection means 3. thereby causing an overcurrent to flow through the charging/discharging line, and that the first switch means 5 opens according to a signal from the control means having detected the overcurrent, thereby opening the charging/discharging line.