US Patent 7898215 Electric power charge and discharge system

An electric power charge and discharge system for an electronic device having a battery, by which the electronic device can be used for a long period of time. In a wireless communication device including a wireless driving portion including a first battery and a wireless charging portion including a second battery, the first battery is charged by electric power from a fixed power supply and the second battery is charged by using electromagnetic waves existing in an external space. Further, the first battery and the second battery are discharged alternately, and during a period in which the first battery is discharged, the second battery is charged.