I am finding this hard to believe it's a simple question. "How much voltage does this GPS use" I e-mailed the techs at garmin 3 times, answer was it uses 3 volts battery (2-AA) or 12 volt adapter. I didn't want the adapter wiring nightmare I already have an adapter for the heat visor. Ram makes a direct wire harness that puts out 5 volts and that's what I want to use if the hcx doesn't need more. I'm assuming the Garmin adapter voltage is reduced but to what voltage?