Patent ID: 8427110

Claim:
A battery system which manages a plurality of battery cells of an assembled battery, comprising: a plurality of battery cell management units which is connected to the battery cells and manages connected battery cells, wherein the battery cell management units are electrically connected to each other, each of the battery cell management units comprises: an operation mode switching unit which selectively switches an operation mode of the battery cell management unit to a slave mode in which the battery cell management unit manages the battery cell connected thereto or a master mode in which the battery cell management unit manages the battery cell connected thereto and controls other battery cell management unit; a parameter-related data generating unit which acquires a parameter of the connected battery cell and generates a parameter-related data; a parameter data transmitting unit which transmits the parameter-related data to other battery cell management unit which is operated in the master mode in case that the battery cell management unit is operated in the slave mode; a parameter data receiving unit which receives the parameter-related data acquired by other battery cell unit from other battery cell management unit which is operated in the slave mode in case that the battery cell management unit is operated in the master mode; a minimum value specifying unit which compares the parameter-related data generated by the parameter-related data generating unit with the parameter-related data received from other battery cell management unit by the parameter data receiving unit and specifies minimum parameter-related data in case that the battery cell management unit is operated in the master mode; a switching command data transmitting unit which transmits a switching command to other battery cell management unit if the parameter-related data specified by the minimum value specifying unit is received from other battery cell management unit, in case that the battery cell management unit is operated in the master mode; and a switching command data receiving unit which receives the switching command from other battery cell management unit which is operated in the master mode in case that the battery cell management unit is operated in the slave mode, wherein in the master mode, if the switching command data transmitting unit transmits the switching command to other battery cell management unit, the operation mode switching unit switches the operation mode of the battery cell management unit to which the operation mode switching unit belongs from the master mode to the slave mode, and wherein in the slave mode, if the switching command data receiving unit receives the switching command from other battery cell management unit, the operation mode switching unit switches the operation mode of the battery cell management unit to which the operation mode switching unit belongs from the slave mode to the master mode.