Battery pack having a protection circuit
View Patent ↗The battery pack according to the present invention is to avoid any trouble or the like of the primary or secondary battery inside the battery pack with a simple mechanical construction when a load is intermittently connected between the external terminals of the battery pack. For this end, the battery pack includes at least the battery cell and a protection circuit for shutting off overcurrent discharge and features in the provision of shut-off holding means and releasing means. The shut-off holding means maintains discharge shut-off condition after abnormal discharge shut-off by shorting or connecting a low resistance between the external plus terminal and the external minus terminal from outside of the battery pack. The releasing means releases the shut-off condition of the shut-off holding means when a predetermined voltage is applied between the external plus terminal and the external minus terminal.
1. A battery pack including at least a battery cell and a protection circuit for shutting off overcurrent discharge to a load, said protection circuit comprising:
an integrated circuit including a overvoltage detection unit;
a discharging shut-off switch controlled by the integrated circuit and connected in series with the load;
a diode wired in parallel to said discharging shut-off switch; and
a shut-off holding unit connected between the battery cell positive terminal and an external negative terminal of the protection circuit, comprising (a) resistor block of resistance larger than 1 kΩ and smaller than 200 kΩ; and (b) a detector in parallel with the resistor block for detecting voltage between an external plus terminal and the external minus terminal,
wherein,
the overvoltage detection unit detects an abnormal discharge of the battery caused by shorting or connecting a low resistance between the external plus terminal and the external minus terminal,
the discharge shut-off switch opens in response to a abnormal discharge, the shut-off holding unit maintains the discharge shut-off in the open position, and
said discharge shut-off switch closes to recover discharge upon detection by the shut-off holding unit of a predetermined voltage between the external plus terminal and the external minus terminal of the battery pack.
2. The battery pack as cited in claim 1 , wherein said detector is one of a charger detector, a voltage detector, a voltage change detector, an A.C. resistance detector, and a voltage dropper.
3. The battery pack as cited in claim 1 , wherein said detector is connected to one of a differentiation circuit, and an one-shot circuit.
4. The battery pack as cited in claim 1 , wherein said discharging shut-off switch is connected between the battery cell negative terminal and the external minus terminal.
5. The battery pack as cited in claim 1 , wherein said discharging control switch is connected between the battery cell positive terminal and the external plus terminal.