Battery pack, battery protection processing apparatus, and startup control method of the battery protection processing apparatus

It is aimed at providing a battery pack which stably implements a protection function of a secondary battery mainly under software control and reduces a circuit installation area and parts costs. The battery pack has a discharge current cutoff means and a charge current cutoff means for selectively cutting off discharge and charge currents of the secondary battery. The battery pack has a protection process means for controlling operations of the discharge current cutoff means and the charge current cutoff means in accordance with an inter-electrode voltage between positive and negative electrodes of the secondary battery. The battery pack executes an initialization process for the protection process means at a timing (T42) when a power supply voltage supplied to the protection process means reaches lowest voltage Vpor to start the protection process means. Further, the battery pack sets a threshold voltage needed for operation control of the discharge current cutoff means and the charge current cutoff means to start the protection process at a timing (T43) when the power supply voltage reaches voltage Vpfw that is higher than lowest voltage Vpor and is smaller than or equal to a voltage for stable driving.