An electrical power supply device configured to interface with a start-stop controller of an internal combustion engine within a vehicle , comprising: a DC-DC power convertor configured to receive an input voltage from a vehicle battery and produce a first output voltage or a second output voltage that is less than the first output voltage provided to a consumer USB device; and a device controller in communication with the DC-DC power convertor and the start-stop controller , said device controller having one or more processors and memory, characterized in that the memory includes instructions which cause the device controller to command the DC-DC power convertor to output the first output voltage in accordance with the device controller receiving a run signal from the start-stop controller indicating that the internal combustion engine is running and wherein the memory further includes instructions which cause the device controller to command the DC-DC power convertor to output the second output voltage in accordance with the device controller receiving a stop signal from the start-stop controller , indicating that the internal combustion engine is not running, wherein the electrical power supply device is disposed within a universal serial bus, USB, port in communication with a USB hub which is in communication with the start-stop controller , wherein the memory further includes instructions which cause the device controller to command the DC-DC power convertor to output the first output voltage in accordance with the device controller receiving a first USB signal from the USB hub indicating that the start-stop controller has transmitted the run signal, and wherein the memory additionally includes instructions which cause the device controller to command the DC-DC power convertor to output the second output voltage in accordance with the device controller receiving a second signal from the USB hub indicating that the start-stop controller has transmitted the stop signal. a DC-DC power convertor configured to receive an input voltage from a vehicle battery and produce a first output voltage or a second output voltage that is less than the first output voltage provided to a consumer USB device; and a device controller in communication with the DC-DC power convertor and the start-stop controller , said device controller having one or more processors and memory, characterized in that the memory includes instructions which cause the device controller to command the DC-DC power convertor to output the first output voltage in accordance with the device controller receiving a run signal from the start-stop controller indicating that the internal combustion engine is running and wherein the memory further includes instructions which cause the device controller to command the DC-DC power convertor to output the second output voltage in accordance with the device controller receiving a stop signal from the start-stop controller , indicating that the internal combustion engine is not running, wherein the electrical power supply device is disposed within a universal serial bus, USB, port in communication with a USB hub which is in communication with the start-stop controller , wherein the memory further includes instructions which cause the device controller to command the DC-DC power convertor to output the first output voltage in accordance with the device controller receiving a first USB signal from the USB hub indicating that the start-stop controller has transmitted the run signal, and wherein the memory additionally includes instructions which cause the device controller to command the DC-DC power convertor to output the second output voltage in accordance with the device controller receiving a second signal from the USB hub indicating that the start-stop controller has transmitted the stop signal. <EOS>