In a battery pack manager that manages series-connected rechargeable unit cells, a cell equalizer equalizes the cell voltages by individually discharging the unit cells according to deviations from reference voltages. An overcharge/overdischarge detector detects an overcharge and an overdischarge state of each unit cell. An inhibit circuit prevents the cell equalizer from discharging the unit cells when the overcharge/overdischarge detector is activated to reduce the cell voltage variability, which would otherwise occur as a result of interference from the overcharge/overdischarge detector, so that the overcharge/overdischarge states of all unit cells can be determined with precision. Connecting lines of the unit cells are monitored to detect a line-cut. The inhibit circuit further inhibits the cell equalizer when the connecting lines are being monitored to reduce the cell voltage variability, which would otherwise occur as a result of interference from the line-cut detection, so that false line-cut detection is avoided.