US Patent 10946751 Power supply device for vehicle

A power supply device for a vehicle includes first and second power supply systems, a switch, and first, second, and third mode controllers. The first power supply system includes: a first power supply including a first power storage and a first generator, and an electrical apparatus. The second power supply system includes a second power supply. When an SOC of the first power storage exceeds a lower limit, the first mode controller supplies electric power from the first power supply to the electrical apparatus. When the SOC decreases below the lower limit, the second mode controller supplies electric power from the second power supply to the electrical apparatus via the switch. When an abnormality is detected to have occurred in the switch during the second power supply mode, the third mode controller supplies the electric power from the first power supply to the electrical apparatus.