Patent attributes
A charging system that includes a charging device and a secondary battery device with improved safety is provided. When the secondary battery device has been connected to a charging terminal of the charging device, a DC voltage for inspection is supplied from a DC power supply unit to the charging terminal to detect a DC signal by a DC signal detection unit, and an AC voltage for inspection is supplied from an AC power supply unit to the charging terminal to detect an AC signal by an AC signal detection unit. The secondary battery device is started to be charged only when the value of the DC signal falls within a reference range defined by a resistance value of the secondary battery device and the value of the AC signal falls within a reference range defined by an impedance value of the secondary battery device.