Patent ID: 8896155

Claim:
An electric power supply system comprising: a battery section having a plurality of rechargeable batteries having a difference in discharge capacities, charge capacities, or maximum charge capacities for outputting a source voltage obtained by connecting said plurality of rechargeable batteries, wherein said battery section comprises: a switch group that switches based on a control signal to select one or some of said plurality of rechargeable batteries to output said source voltage; and a remaining-content measurement section that measures remaining contents of said plurality of rechargeable batteries by measuring voltages of said plurality of rechargeable batteries during a discharge operation and determining remaining contents of said plurality of rechargeable batteries based on said voltages, and outputs said control signal based on a result of comparing said remaining contents, where said switch group selects one of said plurality of rechargeable batteries having the largest remaining content that outputs said source voltage based on a result of measurement by said remaining-content measurement section.