How can you run a 16 volt in-car DVD in car with 12 battery?

You would need to use an inverter to convert your car's 12 volts of DC power to 16 volts of alternating current (AC). AC power is what most devices, including in-car DVD players, use to operate. Inverters are available in a variety of different wattages, so you will need to choose one that is powerful enough to handle the wattage requirements of your DVD player. Once you have chosen an inverter, simply plug it into your car's cigarette lighter or 12-volt power outlet, and then plug your DVD player into the inverter.