# How to make a 12VDC 2Amp water heater(2 3 L)Which element to use.?

HI,
I want to make a 12VDC 2Amp water heater which can heat 2 3 liters of water easily.Actually i havent be able to find any perfect element for that once i torn my old soldering iron and got an element from that and i cut it into half and tried it but didnt get the result.Can anybody help me to make a perfect one.I m not got in electronics and stuff so kindly suggest me which stuff will be use to protect my wire from overheating or short circuts.Waiting for answers!]

Regards,
Muneeb

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iceng24 days ago

Get two of these 1A CAR-CUP-HEATER from Bed Bath and Beyond \$9.97 or eBay \$3.47 with free shipping.

21 days ago

I must admit, an immersion heater made to plug into the car's cigarette lighter socket, is definitely something I would characterize as beyond the bedroom and the bathroom.

Many miles beyond, or as far as the car will travel.

;-)

24 days ago

So for \$35 you could get ten heaters :-)

Jack A Lopez24 days ago

I think you're going to want more power. Or maybe less water. Or less hot.

I mean, the amount of energy needed to heat water from 25 C to 100 C, is about 300 joules, per gram of water ( 300 J/g).

If you actually wanted to boil, make into vapor, that gram of water it would take an additional 2400 J/g.

Merely making water warm, e.g. heat it from 25 C to 50 C, that would only take about 100 J/g.

Anyway, suppose you have a liter ( = 1 kg = 1000 g) of water, and you want to make it merely warm. That will require about (100 J/g)*(1000g) = 100 000 J of energy.

A 24 watt heater (same as 12V * 2 A) supplies 24 J/s, so the amount of time it would take to make 1 liter of merely warm water is (100 000 J) /(24J/s) = 4166 s, which is like, 1 hour +10 minutes.

Also note that this calculation ignores heat lost to surroundings. In other words, I simply assume all the heat from the 24 watt heater is going into, and staying in, the 1000 g mass of water.

The math will get better, if you use a more power heater, e.g. 240 W, 2400 W, etc, or use less water e.g. 100 g, 10 g, etc.

Regarding the problem of designing a heating element, the usual way to do that is to start with some desired amount of power dissipation, like 24 W, 240 W, etc, and then assume your heating element is a resistor, and use Ohm's law to solve for the size of resistor needed for a particular voltage or current.

As an example, for calculating the resistance of a 12 volt, 24 watt, heater, use the formula P =V*I = V*(V/R) = V^2/R

P = 24 W. V =12 V. Solve P = V^2/R for R. Get R = V^2/P

R = V^2/P = (12V*12V)/(24 W) = 6 ohm

For building a resistor from resistance wire, (e.g nichrome or kanthal, et al.) the resistance of some length of wire is proportional to its length, for a particular kind, and thickness, of wire, and there are tables and stuff, for figuring this out.

For a heater to be immersed in water, usually this requires some kind of jacket, like a stainless steel, or copper, tube, to keep the heating element dry. Also some kind of thermally conductive electrical insulation, like fiberglass, or sand, or something, is required to keep the heating element from electrically shorting itself through the metal tube it is enclosed in.

It might be easier to just buy one. They're called, "immersion heater",

https://en.wikipedia.org/wiki/File:Immersion_heate...

and I know the ones made for use with mains power are pretty easy to find, although I am less sure about immersion heaters intended for a 12 volt supply. They're probably out there though.

One thing to keep in mind about immersion heaters, is the water surrounding them is necessary for keeping them cool. If you turn one on while it is dry, it will just melt, or burn itself up, and usually the documents that come with, have some warnings about that.

Downunder35m24 days ago

You can buy 12 and 24V water heaters, if not in your camping store then check where the local truckies buy their supplies ;)
With less 5amps I see little to no success here.
Keep in mind your home water kettle uses 1800-2200W to bring your amount of water to a boil.
And as already pointed out you need an insulated heating coil as otherwise you not only risk a short but also that your heating element fails after a few uses.

rickharris24 days ago

Wrong way to do this (If there is a suitable DIY way).

You need an insulated element. At least 25 watts although 25 watts will be really too small to boil 2/3 ltrs of water quickly and will need a VERY well insulated pot to heat it much at all.

A typical household kettle may be 2 to 3000 watts -

https://www.amazon.co.uk/Streetwize-SWHE-Water-Hea...

you can buy one from amazon in the Uk for £2.99 it really isn't worth making one. Most 12 volt models seem to be about 800 watts which will require much more current than your 2 amps.