Patent ID: 8058878

Claim:
A battery information acquiring apparatus that acquires battery information of a battery cell in a battery pack including a plurality of battery cells connected in series and transmits the battery information to a management unit that manages a state of the battery pack, comprising: a voltage acquiring unit configured to acquire an inter-terminal voltage of the battery cell; a battery information acquiring circuit configured to acquire battery information of the battery cell, the battery information acquiring unit being supplied with the voltage acquired by the voltage acquiring unit as a first power supply voltage and; a transformer configured to have a primary winding and a secondary winding, the primary winding being connected to a common wire to which the management unit and other battery information acquiring apparatuses that acquire battery information of different battery cells out of the battery cells are commonly connected; a communication circuit connected to the secondary winding of the transformer, which transmits a signal of the battery information to the management unit via the transformer and the common wire, the communication circuit being supplied with the voltage acquired by the voltage acquiring unit as a second power supply voltage; a rectification circuit connected to the secondary winding of the transformer, which receives a signal of a predetermined frequency transmitted from the management unit via the transformer, and rectifies the signal of the predetermined frequency to generate a DC voltage; and a control circuit connected to the secondary winding of the transformer, which controls the supply of the first and second power supply voltages to the battery information acquiring circuit and the communication circuit, the control circuit being supplied with the DC voltage generated by the rectification circuit as a third power supply voltage, wherein the control circuit comprises: a first receiving unit configured to receive a first command signal indicating whether or not to supply the first power supply voltage to the battery information acquiring circuit from the management unit via the common wire and the transformer; a second receiving unit configured to receive a second command signal indicating whether or not to supply the second power supply voltage to the communication circuit from the management unit via the common wire and the transformer; a first controller configured to control supply of the first power supply voltage to the battery information acquiring circuit according to the first command signal; and a second controller configured to control supply of the second power supply voltage to the communication circuit according to the second command signal.