Power supply system

A power supply system configured to be mounted on a vehicle, the power supply system comprising:

• a first battery;
• a second battery having the same configuration as the first battery;
• an auxiliary battery having a voltage lower than a rated voltage of the first battery;
• auxiliary equipment connected to a low-voltage power line connected to the auxiliary battery;
• an in-vehicle power generator connected to the low-voltage power line;
• a series-parallel switching circuit including a plurality of relays, the series-parallel switching circuit being configured to switch connection of the first battery and the second battery between series connection and parallel connection by turning on and off the relays;
• a power converter connected to the series-parallel switching circuit and the low-voltage power line;
• and
• a controller configured to drive and control the relays of the series-parallel switching circuit and to control the power converter,
• wherein the controller is configured to, when the first battery and the second battery are to be charged with power from the power generator,
• perform series connection charge control when power consumption of the auxiliary equipment is equal to or greater than predetermined power, the series connection charge control being control in which the controller controls the relays and the power converter such that the first battery and the second battery are connected in series and are charged with the power from the power generator, and
• perform non-series connection charge control when the power consumption of the auxiliary equipment is less than the predetermined power, the non-series connection charge control being control in which the controller controls the relays and the power converter such that the first battery and the second battery are not connected in series and are charged with the power from the power generator.