Patent ID: 7394222

Claim:
A power supply apparatus comprising: a battery that is composed of n, where n is an integer equal to or greater than 2, battery modules connected in series; a voltage detection circuit that detects voltages of the individual battery modules of the battery; and an electronic control unit that controls charging and discharging of the battery based on the voltages of the individual battery modules as detected by the voltage detection circuit, wherein the voltage detection circuit comprises: a voltage detector that detects relative voltages between a predetermined reference node within the battery and each of nodes between the battery modules connected in series; an erroneous detection checker that checks whether each of the relative voltages detected by the voltage detector is an erroneously detected voltage or a normally detected voltage; and a calculation circuit that calculates the voltages of the individual battery modules based on the relative voltages judged to be normally detected voltages, wherein, if one of the nodes is recognized as an erroneous detection node as a result of the corresponding relative voltage being judged to be an erroneously detected voltage by the erroneous detection checker, the calculation circuit calculates, based on the relative voltages detected at the two nodes located adjacently on positive and negative sides of the erroneous detection node, a recovery voltage for the erroneous detection node, and then, by replacing the relative voltage detected at the erroneous detection node with the recovery voltage, calculates the voltages of the battery modules.