| CPC G01R 31/389 (2019.01) [G01R 31/3842 (2019.01); G01R 31/392 (2019.01)] | 14 Claims |

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1. A diagnosis method of a battery, comprising:
determining, based on a measurement result of a first impedance that is an impedance of the battery at a first frequency, whether an absolute value of a change ratio of the first impedance to an SOC of the battery is not more than a reference value, for each of a plurality of SOC values of the battery;
measuring, for a target SOC value for which the absolute value of the change ratio is not more than the reference value in the plurality of SOC values, a second impedance that is the impedance of the battery at a second frequency higher than the first frequency in addition to the first impedance; and
performing determination concerning a state of the battery based on measurement results of the first impedance and the second impedance for the target SOC value.
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