A power inverter is a device that hooks to the tractors battery supply and switches the tractors DC current and turns it into usable AC current. Some tractors have power inverters already pre-installed by the manufacture. When the tractor does not come equipped with an APU from the factory after market power inverters can be installed in order to provide the driver with a usable source of power. Drivers use power invertors to supply power to coffee makers, microwaves, TV’s, Etc.
Some trucking companies prohibit the use of power inverters in their tractors or they will restrict the wattage limit of the device in their tractors. If you are a driver looking for a new carrier to work for then be sure to ask the company if they allow power inverters and what their limit is on the device.