Patent ID: 7962297

Claim:
A failure determination device for a cell voltage monitor which detects cell voltages of a plurality of single cells connected in series at a predetermined interval, the device comprising: a memory for storing the cell voltages detected by the cell voltage monitor; a minimum value determination unit for determining whether or not a present cell voltage detected by the cell voltage monitor is equal to or lower than a minimum value cell voltage which is in a detectable range of the cell voltage monitor; and a failure determination unit for determining that the cell voltage monitor has a failure when the minimum value determination unit determines that the present cell voltage is equal to or lower than the minimum value cell voltage, and a cell voltage detected by the cell voltage monitor in a past and stored in the memory is higher than a determination cell voltage; and a determination cell voltage setting unit which sets the determination cell voltage on a basis of a total output or a temperature of the plurality of single cells as a whole, and further on a basis of a timing at which the cell voltage monitor detects the cell voltage and a decreasing ratio of the cell voltage of one of the single cells or a pair of the single cells in the process of a normal voltage drop, wherein the determination cell voltage is higher than the minimum value cell voltage by a predetermined value, and wherein the determination cell voltage setting unit sets the determination cell voltage to be lower if the total output is greater, or sets the determination cell voltage to be higher if the temperature of the plurality of single cells as a whole is higher.