I installed a high capacity inverter in the cars. So I have 120 volt power available. I also had to change to a deep discharge battery. Now we have enough power on board to run the multi task machines and keep the laptops powered up. But don't waste your money on those little inverters that plug into the cigar lighters. They just don't have the power. You will need to run heavy guage wire directly from the battery to the inverter which can be located inside the car.