12 Volt heaters Options

[Tom]

Hey, has anyone ever tried to use these small heaters to keep the wind shield defrosted and to provide a little warmth on those chilly mornings? If these would work, no more heat exchangers and ducting. Wonder what we could lose in weight and what could be run through the tubes instead of hot air?
Just wondering,
Tom

[jsteele22]

I'd stay away from electric on basic principles. As mentioned, you need a lot of current to get a little heat. The one davep mentioned draws 15 amps and since P=V*I, thats 12*15=180 Watts, which isn't much -- about the same as 3 people generate just sitting around.

For comparison, a dinky little hairdryer is about 1200 watts. If you feel this would be enough heat, don't forget that that (electric) power is coming from somewhere. The alternator has to take power from the engine to make A/C power, which has to be rectified. The efficiency is pretty dismal, maybe 50-60%. So with 746 Watts = 1 HP, you end up using around 3 HP, assuming your alternator could provide an extra 100 amps, which it can't.

The beauty (?) of conventional heat in air- or -water-cooled cars is that the heat is already being produced for "free", all you need to do is move it to the cabin.

One way to solve the heat problem without all that bothersome plumbing (J-tubes, flapper boxes, etc.) and without having to sacrifice valuble trunk space for a gas heater, would be to ditch the passenger seat (you are single, right ?) and stick in a propane barbeque grill. They're simple, reliable, and spare parts are easy to come by. And imagine the savings on road food !