BATTERY SYSTEM AND BATTERY EVALUATION METHOD
A battery system (1) provided with: a secondary battery (10) having a positive electrode (11), a negative electrode (15) and electrolytes (12, 14)
a storage unit (23) for storing pre-measured characteristic information regarding the secondary battery (10), including the initial resistance value and the evaluation frequency
a power unit (20) which applies an AC signal having the evaluation frequency stored in the storage unit (23) to the secondary battery (10)
a measurement unit (22) which measures the impedance of the solid electrolyte interface film (17) of the secondary battery (10) from the AC signal
and a calculation unit (24) which calculates the degree of deterioration and/or the depth of charge of the secondary battery (10) from the impedance and the characteristic information.