Porsche Porsche 356 USB Power Adapter for all 356 models. Years 1950-1965. Finally, an efficient way to power your cell phone or small electronics! Most USB chargers will not work in a Porsche 356. They require 12-volt input power and they donâ™t fit snugly in the 356 6 volt cigarette lighter socket. Unlike many USB chargers for cars, this unit accepts 6-volt power. It should also work in a 356 converted to 12 volts (or Carreras). Also included is a hardwire for a possible permanent power supply.