METHOD FOR DETECTING BATTERY CAPACITY OF SECONDARY BATTERY

A method of detecting a battery capacity of a secondary battery, in which a charging mode when the secondary battery is charged includes a first mode including only an ON state in which a power transmission of a charging power is performed, and a second mode including the ON state and an OFF state in which the power transmission is temporarily stopped, the method includes: a charging mode selection process of selecting the charging mode while the charging is performed; an internal resistance calculation process of calculating an internal resistance of the secondary battery when the ON state and the OFF state are switched from each other; a remaining capacity calculation process of calculating the remaining capacity of the secondary battery based on the internal resistance; a remaining capacity variation amount calculation process of calculating a variation amount of the remaining capacity from a most recent full charge capacity calculation time; a charged electricity amount calculation process of calculating an amount of charged electricity in accordance with an integrated value of the current that flowed from a point of time at which the most recent full charge capacity is calculated; and a full charge capacity detection process of detecting a full charge capacity of the secondary battery based on the variation amount of the remaining capacity and the amount of the charged electricity.