| 摘要 |
PROBLEM TO BE SOLVED: To surely prevent that damage is given to a battery due to overcurrent.SOLUTION: A thermostat 12 with PTC (Positive Temperature Coefficient) is inserted into a discharge current path of a battery cell. The thermostat 12 with the PTC is formed by connecting a current path going through the thermostat with a current path going through a PTC element in parallel. In an ordinary state, discharge current flows via the thermostat. An overcurrent I1 heats bimetal, so that contacts of the thermostat are separated from each other and the overcurrent is bypassed to the PTC element. In addition, resistance of the PTC element becomes higher, and the current flowing through the PTC element is limited or shut down. An off state of the thermostat is maintained, as long as the over-current is flowing. When the overcurrent is lost, the resistance of the PTC element becomes smaller, so that the thermostat is turned on to return to the ordinary state. A characteristic of the thermostat 12 with the PTC is set so that the overcurrent is limited to prevent some damage from being given to the battery cell. |
