POWER SOURCE CONTROL SYSTEM FOR VEHICLE

A power source control system for a vehicle is provided, which includes a traction motor, the system including a first battery that is a bipolar battery and is to be used as a power source for the traction motor; a second battery that is a bipolar battery different from the first battery; a mirror current generator circuit configured to generate a mirror current based on a current flowing through the first battery; a mirror current supply source circuit configured to cause the mirror current to flow through the second battery; and a diagnostic circuit configured to perform degradation diagnosis on the second battery on a basis of at least one of a voltage or a temperature of the second battery.