Abstract: A battery pack includes a secondary battery, a discharge controlling circuit configured to discharge the secondary battery and control an output current supplied to battery driven equipment, a wake-up current detection circuit configured to, in a power saving state in which the output current supplied to the battery driven equipment by the discharge controlling circuit is reduced from a normal non-power saving state, detect that the output current exceeds a wake-up current threshold to make the battery pack transition from the power saving state to the non-power saving state, and a calibration member configured to calibrate a reference point of the wake-up current detection circuit. The wake-up current detection circuit is configured to operate in the power saving state and stop its operation in the non-power saving state, and the calibration member is configured to execute a calibration operation at a predetermined timing in the power saving state.

Abstract: A battery pack includes a secondary battery, a discharge controlling circuit configured to discharge the secondary battery and control an output current supplied to battery driven equipment, a wake-up current detection circuit configured to, in a power saving state in which the output current supplied to the battery driven equipment by the discharge controlling circuit is reduced from a normal non-power saving state, detect that the output current exceeds a wake-up current threshold to make the battery pack transition from the power saving state to the non-power saving state, and a calibration member configured to calibrate a reference point of the wake-up current detection circuit. The wake-up current detection circuit is configured to operate in the power saving state and stop its operation in the non-power saving state, and the calibration member is configured to execute a calibration operation at a predetermined timing in the power saving state.

Abstract: A MOSFET 61 is connected between a power supply IC6 and a 3.3-V power supply terminal. When the MOSFET 61 is turned OFF, a control circuit board 100 is shut down which includes a control portion 5 for calculating RSOC (remaining capacity ratio). When the control circuit board 100 returns from shutdown, the maximum cell voltage is detected as OCV (open circuit voltage). RSOC can be calculated based on the maximum cell voltage by using the discharge characteristic which relates OCV to RSOC. In this case, a quadratic curve line segment is selected from an approximate curve line which approximates the discharge characteristics. RSOC can be calculated by substituting the detected maximum cell voltage into the quadratic function which is represented by the selected quadratic curve line segment.