A charger for charging a second battery is provided. The charger includes a charging circuit, a charging interface, the charger further comprise an audio interface, a switch and a sound output device. The switch used for connecting an audio interface to a charging circuit or a sound output device. When the sound output device connects to the audio interface, the sound output device plays the audio signals outputted by the audio player via the audio interface; when the charging circuit connected to the audio interface, the audio player output energy to the electronic device via the charging circuit and the charging interface, thereby charging the electronic device.