Patent ID: 8269462

Claim:
A state monitoring apparatus for an assembled battery constituted of a series connection of a plurality of battery cells comprising: a high-voltage side monitoring section disposed in a high voltage system having the assembled battery to monitor a state of the assembled battery; and a low-voltage side monitoring section disposed in a low voltage system insulated from the high voltage system and configured to monitor the state of the assembled battery through communication with the high-voltage side monitoring section; the high-voltage side monitoring section including: a voltage measuring section configured to measure battery voltages of unit batteries each constituted of one or neighboring ones of the plurality of the battery cells; a determining section configured to make a determination whether or not the battery voltages of all of the battery units measured by the voltage measuring section are within a predetermined range; and an informing section configured to transmit to the low-voltage side monitoring section a notification that the battery voltage of at least one of the unit batteries is abnormal if the determination made by the determining section is negative; wherein the low-voltage side monitoring section is configured to obtain, upon reception of the notification, at least one of the battery voltages having been determined to be abnormal through communication with the high-voltage side monitoring unit.