POWER SUPPLY SYSTEM AND OPERATION METHOD THEREOF

A power supply system P is provided with a fuel cell and a battery unit connected to the fuel cell The battery unit is provided with a first battery connected to the fuel cell so as to supply power to an auxiliary machine of the fuel cell 1 and to be able to be charged with generated power of the fuel cell a second battery connected to the auxiliary machine of the fuel cell through a path p different from that of the first battery so as to be able to supply power, and switchers R R configured to switch the power supply source to the auxiliary machine of the fuel cell between the first battery and the second battery