Patent ID: 6222346
Filing Date: 2001-04-24
Classification: H02J

Abstract:
A battery protection device incorporated in a rechargeable battery, comprising:a first switching means and a second switching means connected in series in a charge/discharge circuit for connecting a positive electrode of the rechargeable battery to a positive input/output terminal and a negative electrode of the rechargeable battery to a negative input/output terminal; anda control means fordetecting (i) a battery voltage between the positive electrode and the negative electrode of the rechargeable battery and (ii) a terminal voltage between the positive input/output terminal and the negative input/output terminal;turning on the first switching means when the battery voltage is below a charge-prohibiting voltage above which charging of the rechargeable battery must be prohibited, and turning on the second switching means when the battery voltage is above a discharge-prohibiting voltage below which discharging of the rechargeable battery must be prohibited;turning off the first switching means when the battery voltage is higher than the charge-prohibiting voltage and the terminal voltage is higher than the battery voltage, and turning on the first switching means when the battery voltage is higher than the charge-prohibiting voltage and the terminal voltage is lower than the battery voltage; andturning off the second switching means when the battery voltage is lower than the discharge-prohibiting voltage and the terminal voltage is lower than the battery voltage, and turning on the second switching means when the battery voltage is lower than the discharge-prohibiting voltage and the terminal voltage is higher than the battery voltage.