Wednesday, May 13, 2009

Low Voltage Heating Element (4,000 Watts) for $10

by Richard Lewis

Some of you have read my ebook Homemade Amp Meters. In it I talk about using cheap metal such as zinc plated or stainless steel "all thread" or "ready rod" as a shunt for measuring amps. You can run the current through this all thread and take a cheap multimeter and connect the two leads at a very precise distance apart, then the milivolt reading would equal the amps. I include free software with the ebook that computes that distance among other things.

But, what I don't say in the book is that you can use stainless steel all thread as a heater element. For instance, if you were to put in the calculator "shunt calculator" 1/4 inch stainless steel and you have the 1 milivolt (mv) setting, then it would show 1.027 inches as the result. What that also means is that every 1.027 inches of 1/4 inch stainless steel all thread would be 0.001 ohms in resistance at room temperature.

If you take the equation Power = Voltage ^2 / Resistance, and took a 36 inch piece of all thread, then...

12 volts ^2 / (36/1.027) * 0.001 = 4,108 watts. After the stainless steel gets very hot, it increases the resistance and then puts out about 3,000 watts or so. If you were to put cooling fins of some sort that were painted with flat black high temp paint, you could keep it at 3,500 to 4,000 watts or so. Same is true if it were in water.

I know it sounds crazy, but people are spending lots of money on heating elements or some other load for their windmill (when the batteries are charged but the windmill is still spinning). I've seen $25 to $80 per 12 volt heating element and they are only 600 watts. You would have to buy 7 of these and spend $175 to $560 plus shipping just to get 4,000 watts of heating. And those heating elements will burn up if they aren't exposed to water. With the stainless steel, you can use it in the air for an air heater system or you can use it in water. Coolest part is, you can go to the local building supply store to pick it up. I found it at Home Depot. But, make sure it is stainless, not galvanized.

I've also seen the use of light bulbs. But remember, a 100 watt light bulb is meant for 120 volts. If you put 12 volts through it, then you will only be at 1 watt (NO, that isn't a typo, it is really only 1 watt). So, that wouldn't work. You could take car headlamps. They are about 2 to 3 amps. So, that would be 24 to 36 watts each. You would need more than a hundred of them (to equal the stainless steel option) at $5 each. Hmmm, still not a good solution.

You could try a 120 volt heater. But, at 12 volts you would be at 1/10th the voltage and therefore 1/100th the power. So, a 1500 watt space heater would put out 15 watts of heat at 12 volts.

Anyway, I hope you can see the merit of using a simple all thread stainless steel rod as a heating element.



  1. Hi, I'm very interested in making this heater element. I don't how to though. You said it's very cheap and easy, but if you could show me a small drawing or write up on how to make this heater element that would be awesome.
    Ken Orefice

  2. Hello Richard,

    I am also interested in making one of these heaters. Could you please send me the same information as Ken requested? Thank you.



  3. I'm trying to hook a solar panel up to a vegetable oil storage tank (fuel for my '82 VW) so that it won't be frozen in Northern MN winters. What do you think would work for this plan?

    I was trying to envision a solar panel's energy being fed into a piece of metal that would drop down on the inside of the tank. I do not know how to technically do this.

    Any ideas?

  4. This sounds like exactly what I have been looking for. If you could please send me more information on this device it would be very much appreciated. You can contact me at

    Kind Regards,
    Nicholas Rodriguez

  5. Hi Richard

    I was looking to make an outdoor oven, what would the best way be to connect power to the steel rods,would a single copper screw work inserted in the rod.
    I would be grateful if you could send me the same information as Ken and James requested.

    Thank you


  6. it occurred to me that one could, with a suitable means of making electrical connections, use a stainless steel skillet as low voltage cooker. Something like drilling the sides of the skillet and inserting stainless bolts & nuts to secure wires. Could this work?

  7. Joe, you could do that, but I"m not sure what the resistance would be. It would probably be "red hot" at 12 volts and actually get wayyyyy tooooo hot. You would have to test it to see though.

  8. hi richard, i know this is an old thread but i cant find anything else on this.can u tell me where i can find this information on this element as it sounds perfect for an air heater.

  9. This comment has been removed by the author.

  10. The simplest way to connect this would be to take a 12 volt battery and use jumper cables to connect to each end of the stainless steel rod. The longer and the thinner the rod, the less power, heat and amps it will draw. You can also use stainless steel cable and make a coil.


  11. I to need basic info on how to make this.perfect for my e cig project in wich I'm trying to get around a 2700 watt vape at around 90 volts.this is assumeing the element ohms out at 3.38 these are max figures and I'm useing a potetiomiter to adjust volts and watts up or down.a little help please.the stainless allthred would be perfect fit for my plans just need info

    anybody with info can email me

  12. Richard, I am starting up a small project myself, in where I am using Aeroponics in a climate not readily friendly to such an attempt.

    I have looked around and I am rather annoyed at the high costs of a room heater, I am attempting to build a mini one, attached to a small thermostat.

    Your concept sounds interesting, but if you could please contact me and attempt to explain how to make this work it would be greatly appreciated... (schematics, etc)...

    I am working with a space that is probably going to be at this time 2 feet by 3 feet in total space, and about 4 feet tall, perhaps 6 if I can push it... and make it to have a year round food production system.

    What I need is a heating element that will warm the space up, without melting or destroying any of the plants, it's containers, or anything else...

    If you could help me out it would be greatly appreciated. Thanks.

    mpridge (at)

    1. Another question is, would it be possible to convert this wattage into a working power supply?

  13. hi I tested the all threaded stainless idea, well mybe overkill but some cool results. I dead shorted to a 1000cca auto type battery and it took about 15 sec to glow red and continued until the battery when dead. this took about 15 min. amazing , if found my new and only dump load. thanks so much for the amazing idea.