BATTERY STATE DETERMINATION DEVICE

摘要

This battery state determination device (10) is provided with: a voltage detection unit (13) that detects the voltage (V) of a secondary battery (M) to be evaluated; a current detection unit (12) that detects the current of the secondary battery (M); a charge state detection unit (11) that detects the state of charge (SOC) of the secondary battery (M); and a determination unit (11) configured so as to calculate the absolute value of the voltage gradient (G), which indicates the change in voltage with respect to the discharge amount (Ah), when the state of charge (SOC) of the secondary battery (M) is less than 40%, compare the absolute value of the voltage gradient (G) to a pre-set upper limit value (Gmax), and, when the absolute value of the voltage gradient (G) is greater than the upper limit value (Gmax), determine that a small short circuit has occurred in the secondary battery (M).