Power source device for vehicle

A vehicle power supply apparatus comprising:

• a generator installed in a vehicle;
• a high-voltage first battery that is connected to the generator and stores an electric power generated by the generator;
• a DC-DC converter located between an electrical equipment, and a node between the generator and the first battery;
• a second battery that is connected to the first battery via the DC-DC converter, and that has a lower voltage than the first battery;
• a control section configured to cause an increased current flow through the first battery and to detect a deterioration of the first battery from the increased current flow, wherein the control section controls an operation of the DC-DC converter to cause the increased current flow through the first battery during a battery deterioration detection operation performed by the control section;
• a measurement section that measures the increased current flow through the first battery during the battery deterioration detection operation, in synchronization with the control of the DC-DC converter by the control section that causes the increased current flow through the first battery during the battery deterioration detection operation performed by the control section;
• and a determination section that determines the deterioration of the first battery using a measurement result of the measurement section, wherein the measurement section measures the increased current flow through the first battery after the control section has, during the battery deterioration detection operation, temporarily stopped the DC-DC converter during a vehicle deceleration.