Patent ID: 8912756

Claim:
A battery system, comprising: a unit lithium battery cell assembly including a plurality of unit lithium battery cells that are electrically connected in series and each include a plurality of lithium battery cells that are electrically connected in series; a plurality of integrated circuits that are provided to respectively correspond to the plurality of unit lithium battery cells, each detect voltages of a plurality of lithium battery cells of a corresponding unit lithium battery cell, and each adjust a state of charge of each of the plurality of lithium battery cells, wherein: each of the plurality of integrated circuits includes a plurality of voltage terminals that are provided to be used to electrically connect with terminals of the plurality of lithium battery cells of the corresponding unit lithium battery cell, a voltage detection unit that detects terminal-to-terminal voltages of the plurality of lithium battery cells of the corresponding unit lithium battery cell that are taken in from the plurality of voltage terminals, a plurality of state-of-charge-adjust terminals that are provided to be used to adjust a state of charge of each of the plurality of lithium battery cells of the corresponding unit lithium battery cell, a plurality of switches that are respectively and electrically connected with the plurality of state-of-charge-adjust terminals, and each form a discharge circuit at each of the plurality of lithium battery cells of the corresponding unit lithium battery cell, a driving unit that drives each of the plurality of switches, a communication unit that inputs/outputs a signal, a signal input terminal that is provided to be used to input a signal to the communication unit, a signal output terminal that is provided to be used to output a signal from the communication unit, a switch abnormality detection unit that detects an abnormality of each of the plurality of switches, wherein: the switch abnormality detection unit detects an abnormality of each of the plurality of switches by judging whether or not the switch is operated according to driving operation of the driving unit, and outputs an abnormality detection result from the communication unit via the signal output terminal.