DIY 12V water heater (+advice/thoughts?)

ewerbos

Songster
6 Years
May 14, 2016
109
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Gaithersburg, MD
My husband and I just started with chickens this year, and we plan to be away from home for the first time over Christmas (Dec. 23rd to 26th). We have 6 chickens in a 8x10 coop, which they like, so we're pretty comfortable there, but we still don't have a watering solution. It's been a little cold--Their water has only frozen a couple of times, usually when the level is low (they are using a 1 gallon fountain waterer right now). However, if it's cold over Christmas, we're going to need to do something to keep their water unfrozen. Our coop is 200'-250' from the house, so there's no way we can run an extension cord. I got a deep cycle car battery (will add solar, but I believe it should be enough for a couple of days at a time). We don't want to use an inverter and crank it up to A/C and high voltage, because of the risk of fire and efficiency losses.

Thus, the requirements for our heater:
-12V
-Low-power (to reduce fire risk)
-Immersible but safe when water is empty

I looked around but didn't actually find anything I liked. There are immersible heating elements on amazon, but they're typically pretty high power (150W+), which is an increased risk for fire or overheating.

The solution I am trying now is DIYing a heating element with nichrome wire. I used a nichrome wire calculator http://www.jacobs-online.biz/nichrome/NichromeCalc.html to determine that 42" at 28 gauge should do 15W and stay below 200F at room temperature (obviously I'd expect the water to be typically much less than that, but safety). I took a pizza tray that would fit in the bottom of a 5-gallon bucket and slathered it with food-grade high-temperature silicone sealant, placed the nichrome wire on top (with silicone-coated ordinary wire for connections already attached) & waited for it to cure (using a multimeter to make sure the wire wasn't shorted to the pizza tray... I should have waited for the silicone to cure before adding the wire, but I didn't). The wire didn't stick very well, so for the next step I ran silicone sealant just around the wire, covered with wax paper, then clamped another pizza tray on top to keep it flat. I let it cure for a bit, then pulled off the pizza tray and the wax paper (slightly before it was fully dry, so it stuck a little). I then waited for it to cure, then ran some more silicone sealant over to make the top waterproof as well. At this step, I also put the connection wires through silicone tubing to make them more waterproof/less likely to pull/break (not sure how necessary that is) and sealed the tubing to the overall object.

I waited for it to dry, and immersed it in water, testing with the multimeter to make sure it wasn't shorting to the water and that nothing wacky was going on. So far, so good--Now I need to actually hook it up to a power supply, and test and configure the temperature controller I got to keep it at just above freezing. I also need to put the horizontal waterers in the bucket (...and teach chickens to use horizontal waterers...).

The multimeter measures the heating element at 10 ohms, which at 12V comes to ~14.4W, which is about what I was aiming for.

Here's a photo of the object on the counter:
IMG_20171210_231300.jpg

And here it is immersed in the bucket for the first test:
IMG_20171210_231000.jpg

Any thoughts? Is this crazy? Will it work? I'll see with tests, probably (actually powering it is key of course). Please let me know of any safety concerns, in particular (I already purchased fuses and fuse holders for connecting to the battery [planning on using 3A] to reduce the risk if anything goes wrong).
 
I saw threads with that suggestion, but that's not going to work, since we haven't made the large run yet and they'll be inside (coop is 8x10 for 6 chickens, so no space issues), and thus nowhere to dig a hole where they have access.

And I don't have manure lying around that I could fill a tire with it. Or a tire, come to think of it.
 
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That’s a cool project, nice job!
Keep us up to date on how it works out.

May I suggest getting a solar panel that is far larger than the minimum you anticipate needing. There will probably come a time when it’s cold with little daylight and the panels output will be very low, possibly not keeping up with the demand over a 24hr period.

Your chickens will catch onto horizontals quickly. When I start training chicks I use a red laser pointer, the chicks chase it as I move the dot toward the nipples, once on the nipples their instinct is to peck the nipple, they discover it supplies water and they are away. That’s a little tip from someone on here, thanks whoever you were!
 
My original solar panel idea was getting a 150W one (we'll want lighting eventually), and then all the wires and charge controller and mounting it on the roof with a crazy bracket (I just built that thing waterproof, why would I want holes in it??), and.... I might just buy a 10W-20W guy to start with, depending on how much power the heating element *actually* uses over the course of a cold winter day.
 
Haha wow! So I actually purchased that exact item (it takes a while to ship) as an alternative in case my crazy didn't work. I was going to put it inside the bucket... To make it waterproof, silicone tubing for the wire connections (similar to the thing I already made), and I was planning on putting the circular heating element itself inside glass candle holders and then putting some clear silicone caulk over top to make it waterproof. That one may actually work better than my first version, but the shipping for the heating element from China wasn't guaranteed before Christmas.

I also think I could do the full DIY version much better a second time (e.g., using cheaper/clear silicone caulk that should still work, making thinner layers and letting it seal in between, maybe using something besides a pizza tray for stiffness...).
 
I'm also not sure how hot the heating element will get. Probably not too hot, given wattage and size--I guess I could search for it, but I was going to determine empirically once it gets here. Outside the bucket is a really great idea, if it's not too hot for the bucket (bucket is Polyethylene, so heat tolerant up to like 248F according to googling?). That's lots less effort...
 
The attached file is a BTU calculator I wrote when I was brewing a lot of beer... funny things you do when your not fully overwhelmed with work. May or may not be of some help.

JT
 

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So I performed some leisurely additional testing when objects came, was prepping to get it ready for Christmas--wasn't in a hurry, plenty of time, plus the weather was looking like it wouldn't freeze while we were away anyway, so maybe not even necessary... then I got the flu for a week and the weather looked like it was going to get icy two nights in a row while we were gone, with fairly low daytime temperatures... So, I finished it up quickly today. Tested everything inside, seems to heat, made sure the chickens are drinking from it. No solar is connected, but the battery should last 24 hours of running the thing continuously, and we'll only be away for three days, so hopefully it will work out.

I hadn't soldered in something like ten years, plus am still getting over the flu, so it was somewhat of an adventure! But I'm really happy about how it came out.

All parts assembled and being tested in the basement (Battery is 35Ah deep-cycle battery, sealed inside a battery box). Battery is connected inside of the box with clips attached to a 3A fuse (maximum draw of heater should be about 1.5A). I left it connected set up to heat to a temperature slightly above room temperature long enough to observe that it was, in fact, heating:
IMG_20171222_151343.jpg


Close-up of the temperature controller in its box. It can be set to heating or cooling, with customizable hysteresis and target temperature:
IMG_20171222_151348.jpg

Battery inside coop:
IMG_20171222_160823.jpg

Heater setup on other side of coop--with proof the ladies will use the new waterer! Though it is a bit low. We left their usual waterer in as backup:
IMG_20171222_160756.jpg

We're hoping they won't fuss with the wires too much; we can secure them more if it proves to be an issue.

Next steps: Solar panel and lighting! It will be useful to see how much power was used to keep the water defrosted while we were away (assuming it works)--will give a better estimate of how large a solar panel we will need.
 

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