ELECTRICAL POWER SUPPLY DEVICE

An electrical power supply device is configured to communicate with a start-stop controller that automatically shuts down and restarts an internal combustion engine in a vehicle. The device includes a DC-DC power convertor and a device controller. The DC-DC power convertor is configured to produce a first voltage or a second voltage that is less than the first voltage. The device controller causes the DC-DC power convertor to produce the first voltage in response to a first signal from the start-stop controller indicating that the input voltage will remain equal to or greater than the threshold voltage and also causes the DC-DC power convertor to produce the second voltage in response to a second signal from the start-stop controller indicating that the input voltage may become less than the threshold voltage.