Troubleshooting methods for energy storage devices and current interruption devices

Abstract

To provide a current cutoff device capable of improving failure diagnosis accuracy due to improvement in current measurement accuracy, and the failure diagnosis method thereof.SOLUTION: A power storage device 50 comprises a current cutoff device 53, a resistor 54 for current measurement provided in a second power line 55N for connecting a plurality of cells 62 and others of an external terminal; a discharge circuit 120 connected in series to the plurality of cells 62 and the current cutoff device 53, and a control device 130. The discharge circuit 120 comprises a discharge resistor 121 and a discharge switch 123. While the control device 130 controls the current cutoff device 53 to open, it measures current I with a resistor 54 in a state in which the discharge switch 123 is controlled to close and in a state in which the discharge switch is controlled to open, and diagnoses a failure of the current cutoff device 53 on the basis of a difference ΔI between a current value I measured in a state in which the discharge switch 123 is controlled to close and a current value I measured in a state in which the discharge switch is controlled to open.SELECTED DRAWING: Figure 5