DIY electric car heater


[lgtngstk] was tired of driving his cold Honda Civic to work. He built an instant on electric heater for his car from a toaster and an ATX power supply. The toaster elements were mounted to one half of the case, while the fan was left in it’s stock location.To get the fan blowing hard enough, he whipped up a DC voltage doubling circuit. To finish it out, he added relay control and plenty of new holes in the case.

45 thoughts on “DIY electric car heater

  1. The only addition I would make would be some sort of heat control to turn off the electric when the actual car heater caught up. thermocouple or some such.

  2. At this point, you may be asking yourself, “Why would I want to make a car heater when I could just order one from XXX?” If so, you may also be saying other things like: “This is too dangerous,” or, “Why does my diaper always get so soggy?” If that’s the case, then you should stop reading now and go back to marthastewart.com.

  3. “If that’s the case, then you should stop reading now and go back to marthastewart.com”

    you know, that excuse formula doesn’t work for *every* idiotic thing someone might do.

    jury-rigging toaster guts into your beat-up civic isn’t exactly “we’re going to the moon because it’s there” material.

  4. The cars heater takes the heat from the radiator/engine, and redirects it to the passengers. As he said, his engine takes a while to warm up, so it blows cold air at you until it does. IDK why they dont just stick an electrical heater in the tube if the temp isn’t high enough…

  5. @lgtngstk: First, I’d suggest changing the wallpaper to something MUCH more neutral. Solid colors really seem to be the prevailing aesthetic these days…

  6. My friend’s volvo 850 had an electric heater from the factory. The vent air was instantly warm as soon as you needed it to be, then it shut off and the engine coolant kept the car warm. It worked great, it just smelled like electronics when you turned it on.

  7. The detailed instructions in this post suggest using 1N914 or 1N4148 diodes in the voltage doubler. There is *no way* that a 1N914 or 1N4148 diode can carry 4 amps, For example, the max current spec for the 1N4148 is 450mA (0.45 A) about ten times too small.

    If you use those parts and the current load is 4 amps, you can expect flaming debris. Please wear eye protection.

  8. Good idea with some bad choices. Either Martha Stewart or Rachel Ray could tell the author that most 90mm computer fans are of cheap construction, and will fail quickly being driven at twice the intended voltage.

    Should the fan fail, or become obstructed as a result of something falling through any of the excessively large holes cut in that thing, you have a problem. Especially if the heater is left unattended while waiting for the car to heat up.

    I’d recommend:

    1) Mount a thermal cutout to the casing/heatsink.
    2) Replace the fan with one with sufficient airflow at 12v (cheaper, easier, and more reliable than this voltage doubler nonsense).
    3) Use some aluminum window screen to cover the holes.
    4) Bonus: Add a heavy-duty relay to control power to the heater. The coil should be actuated only when the car is actually running. Avoids the possibility of accidentally leaving this on and destroying your battery/car.

    Martha also has a few aesthetic recommendations, but I’m leaving those out. :)

  9. I added a picture of the unit in operation and removed the background image everyone was complaining about, though I may bring it back in some sort of css page centering thingy.

  10. if you chose, you can make this more efficient by heating up larger pieces of thin metal (crap thin aluminum, but not foil) at an angle, so the air is forced across it (radiator.) it will transfer more heat directly to the air and less to the atx chassis. ill leave it to you to figure out how to insulate it electrically but not thermally :)

  11. “Any constructive comments about how to improve my website?”

    Sure thing.

    Center a navigation at the top or bottom-stylized text is great. Trash the splash page. Learn CSS and make a couple standard layout pages.

    Or you could install WordPress. It looks like what you would be great on a blog-type interface and system. Updates are easy, install is easy.. these are thousands of styles to choose from, and a fair amount of customization can be done by switching images in the designs out.. good luck.

  12. Extra points for anyone that fits one that retains the ability to make toast. Kill 3 birds with one stone by heating up some breakfast pop-tarts on the way to work for that internal and external glow.
    How about the George Foreman grill/window de-icer too :D

  13. you’d probably need to add more coil if you wanted to still make breakfast with it since it would be blowing out most of it’s heat. in any event, it’d beat the hell out of onstar if you ask me.

  14. Honestly… his car should heat up within 5 minutes. Is it worth the extra current draw/fire risk from this? I seriously doubt it.

    If the car isn’t heating up… fix it :p

    (I have that year/make/model car…. it heats up quite quickly and has a great heating system)

  15. Wow, y’all a bunch of girlie-girls… ooh, it’s going to catch on fire… ooh, it’s going to damage the altenator…

    and you guys (gals) call yourselves hackers. you should be ashamed. ashamed, I say.

    perhaps you don’t know the retail products are basically the same thing. they’ve sold electric car heaters for many years, it’s not new. or that not everbody desires to wake up 45 minutes early to allow their car to thaw out before they can go to work. or that old vw’s used _gas-fired_ heaters, but your parents survived to have you.

    it’s a cool hack. get over the website.

    and be sure to have parental supervision before you make some pop-tarts…

  16. @Jentulman: Both of those ideas are just begging to be hacked, or at least photoshopped.

    Of course with the toaster/heater combo you’d also have the side effect of making the entire car smell like whatever you were toasting. It could be a huge plus for older cars that smell, well, “broken-in”. I know i’d take “brown sugar and cinnamon” over “mildew and road-tar” anyday.

    The foreman grill de-icer, I’m not sure how you’d do that; does the heating element come out of those? It might be best kept intact as a roof-top unit that allows hot grease to drip-down and de-ice the windshield (wet-naps not included) while your breakfast sausages cook.

  17. I dunno why the other parts were deemed “un-needed”. The thing would make a rather good bagel toaster for the drive in to work.

  18. I had a 79 Honda AccordLX that had from the factory electric heat in the vents. It also shut off when the incoming air was warm enough.

    Also had a coworker that made something like this 15 years ago when he heard me talking about my Honda. What he did, though, was to use little 12V heating elements (kinda like 4″x8″ heating pads) that came out of military battery packs. He wired them to the car’s 12V system with a dashboard switch and put a thermal switch in the vent before the heating pads to shut them off when the incoming air got to something like 100 degrees.

    Worked great! The heating elements could not get hot enough to damage anything since they were designed to go up against batteries in a plastic enclosure, but got plenty warm enough to get his big old Ford LTD warm right away in Michigan winters.

  19. why didn’t he just use a blow dryer? they are designed to blow air over the coils, most likely have a thermal cutoff switch to keep the air from getting too hot (like say, a temperature you could make toast with) and you could keep the entire “barrel” assembly (think of the blow dryer in gun terms) because the coils are already mounted and electrically insulated from each other

    youre using a flamethrower to do the job of a flyswatter. a flamethrower has more power, but a flyswatter won’t burn your house down. choose the right tool for the job

    used a propane space heater (the ones that mount on the little bottle you use camping) to heat my truck when it was -5f once

  20. I think we’re all looking at the problem the wrong way. Under the hood there is an item that warms up straightaway – the engine exhaust pipe. Put your hand on it if you don’t believe me!
    Air cooled Porsche cars have a hot box – a steel box that fits around the top of the exhaust where it meets the engine. Air is blown over this and it heats up instantly. Not that I’ve got a porsche, the 1970 440 cu inch roadrunner in my garage warms up PDQ without the aid of a heater anyway!

  21. you are a genius dunkoriffic… actually whoever thought of that… but thank you.

    once i get access to a mig (or get around to fixing mine, if possible) i’m going to weld a box around the tailpipe with a couple hose fittings on it, and hook that up to a y-mixer, one side from the hotbox and the other to ambient air, add a thermistor to the outlet to adjust the mix ratio so i don’t get air hotter than 120 or so (thats what water heaters are set to to prevent burns) and add that into the air system. thats a great idea!

  22. Actually… i have a 911 that needs heating/demisting, as the exhaust/heater component has been removed, (different exhaust)
    I actually need an electric heater..
    any best recommendations

  23. Darn it
    I just entered a long and comprehensive comment, but when I tried to send it my Internet Explorer crashed.
    Did it come though or is it lost and I have to do it again?

  24. It may be easier to just put some cardboard in front of your radiator. This will cause the engine to warm up faster as the coolant is unable to cool as well. I used it in a Geo Metro & it worked fine. Much safer, just make sure you don’t overheat the engine.

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