Instructables

Cordless Car Heater

Hi all,

I am camping in my SUV in northern CA. It's a bit cold at night and in the morning, and can stay warm with blankets and a sleeping bag, but, when I get up, and want to change clothes or just sit, it is really cold.

It's a 1999 Ford Explorer V6, and I am trying to find or make a device that would heat the interior without turning the engine on. 

I've seen handwarmers on amazon and ebay, but I don't see anything that warms that much space without a plug and without CO2 emission.

Any ideas?

Toga_Dan8 months ago
i tend to shy away from inverters in cars, since 120v can be risky when you might be dealing with damp. However, I have chopped xmas lites into 1/10th their original length in order to run em at 12v. One might do something similar with filament from a space heater. I'd suggest rigorous testing to be sure it's not gonna spark, etc.
eadmati (author)  Toga_Dan8 months ago

Thanks all. Good ideas. Had a few warm days, hoped it would be the trend. But, had a cold one last night, and made me wish wish for a warmer climate.

Had an idea. Since my SUV (and most cars) already has a heater, wondering
if I can use that, a switch and a second battery, to run it at night, when my vehicle is turned off.

A few questions come up:

1. How can I rig it up? I know a little about wiring, have
an engineering background, but it's been years since my Circuits class.

2. Since running it at night would add a lot of 'mileage' to
said current heater, how hard or expensive is it to replace in the event it gets overused?

3. Using an extra battery - I've been reading up on getting one, another 12V or 2 6V ones. How would I handle recharging it/them - alternator or via a solar panel? How would I hook it up?

4. Thermostat - to keep it from running constantly.

5. Granted it all went well... and I hooked it up, ...
wondering, if it would make noise, as some nights, I will be doing this in nicer neighborhoods I am considering living in, don't want to pay for hotels, so I want to keep quiet...

Toga_Dan eadmati8 months ago

re your question 3, I would be inclined to put the spare battery under the hood. I'm not sure if a relay is available to dsconect the kinds of amps we're talking about from the car's charging system. There are, however, heavy duty switches designed for disconnecting a car battery.

Toga_Dan eadmati8 months ago

re your question 3, I would be inclined to put the spare battery under the hood. I'm not sure if a relay is available to dsconect the kinds of amps we're talking about from the car's charging system. There are, however, heavy duty switches designed for disconnecting a car battery.

Toga_Dan eadmati8 months ago
A car's heater uses waste heat from the engine. Cooling water circulates through the engine, and then through a small radiator which transfers heat to you. I 've considered some method to use the residual heat in the engine once the engine is shut off. Most cars have a mechanical connection from the engine to the water pump. Once you shut off the engine, water stops flowing, and running the heater no longer produces heat. Its not trivial to disconnect the mechanical linkage and run the water pump electrically. Even if you did so, the heat would only last until the engine cooled.
caitlinsdad8 months ago
They do have those tiny car heaters/defrosters that work off of 12V cigarette lighter plug. You might want to throw an extra car battery into the back to power those little "hair dryers". I think the big problem is that cars are not really insulated. Maybe you should make a big thermal blanket to throw over the car when it is parked and camping. Good luck. (I also think you are looking for something that does not throw off CO - carbon monoxide, anything that burns fuel for heat like a gas stove or candle)
If you have a battery in the back of the SUV, I suggest a sealed one. Battery acid can be a mess. You could probably find room for a 2nd batt under the hood, too. I'd recommend a cutout switch between your 2nd batt and the main electrical system. that way, the system will charge your heater batt while you drive, but your not draining your main battery with your heaters.
Toga_Dan8 months ago
insulate windows while you sleep. roof is somewhat insulated already. maybe a curtain between sleep area and "cab" too.