DISCONNECTION DETECTION DEVICE AND DISCONNECTION DETECTION METHOD

A disconnection detection device includes CR filters, discharge circuits, and a detection unit. The CR filters are provided for respective battery cells of a battery pack in which the battery cells are connected in series. Each of the discharge circuits is connected between the battery cell and the CR filter and discharging the battery cell when cell voltages of the battery cells are made balanced. The detection unit successively discharges two of the battery cells connected in series, successively detects voltages of detection lines detecting contact voltages of the two battery cells after a predetermined time has passed from finish of discharge of each of the battery cells, and detects disconnection of each of the detection lines on the basis of a difference between the two detected voltages.