VEHICLE POWER SUPPLY SYSTEM

A power supply system for a vehicle includes a high-voltage battery that supplies electric power to an on-vehicle motor, a low-voltage battery that supplies electric power to a plurality of on-vehicle auxiliary machines, a DC/DC converter that changes voltage of an output from the high-voltage battery and supplies the resulting output to the low-voltage battery, and a controller that detects a working state of at least one of the plurality of on-vehicle auxiliary machines and controls operation of the DC/DC converter in accordance with the detected working state.