Patent ID: 8299757

Claim:
A battery system comprising: a battery module having an assembled battery formed by electrically connecting a plurality of cells; and a battery controller configured to detect states of the plurality of cells of the battery module, control the plurality of cells of the battery module, and transmit and receive information to and from a controller of a host system, wherein the battery module includes: a storage device adapted to have stored therein at least one of electrical characteristic information and usage history information on the cells or the assembled battery, as battery information, a battery controller communication interface circuit configured to communicate with the battery controller, and a storage device control circuit configured to, in response to an instruction from the battery controller, read the battery information stored in the storage device and transmit the read battery information to the battery controller via the interface circuit, and receive the battery information transmitted from the battery controller via the interface circuit and write the received battery information into the storage device, wherein the battery controller includes: a battery module communication interface circuit configured to communicate with the battery module, means for transmitting to the storage device control circuit of the battery module an instruction to read the battery information stored in the storage device of the battery module and the battery information to be stored in the storage device of the battery module via the battery module communication interface circuit, means for receiving the battery information via the battery module communication interface circuit, the battery information having been read from the storage device of the battery module in response to the instruction to read the battery information, and transmitted from the storage device control circuit of the battery module, and a host system communication interface for communicating with the controller of the host system, and wherein the battery module and the battery controller are configured to be separable.