Need a small 12VDC heater
I have a 2005 Fleetwood Excursion 39S DP with good front air conditioning and heat. Having said that, there's a cold spot under the dash where my feet are so I'm looking for a small 12VDC heater to mo...
Forum Discussion
KD4UPL wrote:
You could try just wiring up a standard little 120v electric heater. Resistance heating elements don't care if they have AC or DC flowing thru them. A 1500 watt heater on 120v would be roughly a 150 watt heater on 12v. I would think that might be about right to warm up the foot area under the dash.
The problem might be the fan in the heater. Ideally you'd find one with no fan but that would probably be kind of large. You might be able to swap out the fan motor for a 12v DC model.
A 1500W 120V heater uses 12.5A and so has a resistance of about 9.6 ohms. Assuming the heating element resistance is constant with temperature (which is not exactly true), this would mean 1.25A at 12V, or a power of 15W. That's not enough heat to really be noticeable.
In more general terms, for a purely resistive load, power varies with the square of applied voltage. For a factor of ten difference in voltage, the power consumption changes by a factor of one hundred.
More readily practical might be installing an inverter and using a low-powered 120V heater off of that. A heating element would be just fine with an MSW inverter, though the shaded pole fan motors used in many heaters might not run quite as well.
