Battery pack malfunction detection apparatus and battery pack malfunction detection method

A battery pack malfunction detection apparatus that detects a malfunction in a battery pack constituted with a plurality of chargeable/dischargeable cells, comprising:

• malfunction detection devices each provided in correspondence to a predetermined number of cells to detect an overcharge malfunction in the corresponding predetermined number of cells during an overcharge detection period and to detect an over-discharge malfunction in the corresponding predetermined number of cells during an over-discharge detection period;
• a decision-making device that makes a decision as to whether or not a cell in an overcharge malfunction state or a cell in an over-discharge malfunction state exists based upon a signal input from each of the malfunction detection devices through a single signal line;
• a clock signal generator;
• and
• a switch, wherein:
• each of the malfunction detection devices outputs a first signal if an overcharge malfunction is detected in any of the corresponding predetermined number of cells and outputs a second signal if no overcharge malfunction is detected during the overcharge detection period, outputs the second signal if an over-discharge malfunction is detected in any of the corresponding predetermined number of cells and outputs the first signal if no over-discharge malfunction is detected during the over-discharge detection period, and the clock signal generator controls the switch to repeatedly select the output signal to the single signal line during the overcharge detection period and the output signal to the single signal line during the over-discharge detection period to the decision-making device.