12 volt DC water heater

[mep1811]

I am planning to install a 12 volt heater element into my shower system. Has anyone tried this? The element is a 600 watt = 50 amps but it will be only heating a gallon of water so I don't think it will draw the battery down. .

I will have quick disconnects so I'm not dragging wires into the shower. The element came in and I drilled a hole in the tank being careful to avoid the pump mechanism. The tank was too thick to screw a retaining ring on the inside of the element but the element threaded into the hole very snuggly. I did find the supplied gasket not seating evenly and in trying to make it work I torn the gasket. Next up is a trip to Lowes.

 

[woody]

Interesting concept, curious how long it will take to heat the water. Please keep us up to date on your findings!!

 

[Herbie]

Interesting concept, curious how long it will take to heat the water. Please keep us up to date on your findings!!

I'm curious too. Let's do the math:

1 Gallon of water (stated volume) = 3780 grams
600watt heater (assuming 100% efficiency) = 143.31 calories/second (http://www.kylesconverter.com/power/watts-to-calories-per-second)
(1 calories warms 1g of water 1°C)

So, the heater should be able to raise the water temp 1°C in 3780/143.31 = ~26 seconds.
In 'murican units, that's 1°F in ~14.5 seconds

Assuming you want to take 1 gallon of ~60°F water up to ~100°F ( for bathing or dishes), you need ~10 minutes.

Now, that's assuming 100% efficiency of the watts CONSUMED (600w) into calories. In truth, you won't get 100% efficiency, but DC elements are pretty good, so you're not too far off these numbers.

The real question is whether or not your power system can really source ~50 Amps for 10+ minutes. That's a pretty rocking amount of current. You could probably weld with that current. In battery terms, that's like 8 or 9AH. And drawing at that rate puts the battery into a very inefficient state. (Remember that most batteries are rated at a 20-hour draw rate, i.e. a 100AH battery is rated at 5A for 20 hours.) Drawing 10x the nominal draw rate will not net you anywhere near the same total amp-hour capacity from the battery.

I'm not saying this won't work, but I think you might find that using a hydrocarbon fuel would allow you to heat more water, faster, and with less penalty to your wallet and battery bank.

 

[woody]

Wow....

 

[Andy]

For some reason this popped in my head.

[video=youtube;rGWmONHipVo]http://www.youtube.com/watch?v=rGWmONHipVo[/video]

Sounds like it could work, just might be very inefficient. A temp switch to cut off the power and plug it in while your engine is running, maybe?

 

[mep1811]

I sealed the element and filled the tank with 60 degree water. I was wrong the tank is a two gallon tank.


I applied power at 1750 with 60 degrees


1825 hrs = 100 degrees
1835 hrs= 110 degrees
1840 hrs= 120 degrees


So almost an hour to get to 120 degrees. Obliviously as the temp got higher the faster it kept heating.


The process brought the battery down to 11.5 volts but the water kept getting hotter.


So I am thinking the best way to manage this system is to plug the tank in while driving (an hour before stopping) it will heat at 13.9 volts and get the water nice and hot with out any expenditure of power other than the alternator charging the battery.

 

[Phulcrum]

i like the idea of turning it on while you're driving.

i use an eccotemp on demand 12v/propane heater because i didnt have the option of running a motor while heating the water. (its in a trailer)
the 12v element route is how i wanted to heat the water in my trailer but i couldnt get past the battery death problem.

 

[mep1811]

I forgot add the temperature outside was 45 degrees.

 

[Borrego60]

Interesting idea. I have a 13gal water tank in the back of my vehicle and run a water cirulating pump to a helton while I drive around ECO friendly and I have hot water when I get to camp. I does not take long to heat up 13 gals of water. When driving from 50 to 120 in about 15min.

 

[mep1811]

Interesting idea. O have a 13gal water tank in the back of my vehicle and run a water cirulating pump to a helton whhile I drive around ECO friendly and I have hot water when I get to camp.

Great Idea.

 

[TangoBlue]

Interesting idea. O have a 13gal water tank in the back of my vehicle and run a water cirulating pump to a helton whhile I drive around ECO friendly and I have hot water when I get to camp.

Smart idea!