US Patent 10523026 Electric power supply system

An electric power supply system includes a charger, first and second high electric potential side lines, first and second diodes, a first battery and a first load, a second battery and a second load, a first switch, a second switch, and a control device. The control device is configured to switch the first switch to an open state and maintain the second switch in a close state when the first battery reaches a predetermined level or higher of a state of charge earlier than the second battery after the control device starts charging the first battery and the second battery.