Ideas for heat using car battery and timer to go on at night


11 Years
Sep 10, 2008
Upper Michigan
Hi folks. I need to figure out a heating option that can be done with a car battery. We are still building and didn't get far enough for power this year. We can get to -20 at night during the winter months and I only need it to heat the roosting area which will be curtained to about a 10'x4' area and heated to about 40 degrees.

I do have a converter that connects to a cigarette lighter to use household things while traveling. I thought about connecting a ceramic heat bulb this way but wonder if that would draw too much power out of the battery to be practical. I'd also include a small florescent bulb for light if I went this way. The battery would only be able to be charged with a generator so I would like to avoid having to charge it too often. I seem to remember seeing a plug in device that turns things on when the temperature gets below 32, I can't remember where I've seen that. Anyone khow?

Any recommendations?
I'm sorry, but what you describe will need much more than just one car battery. A single 250w heat lamp will probably not be sufficient to raise that size area to 40 F (! - see below) unless you have massive insulation; and even just ONE 250-watter will require more than one car battery's worth of charge for the night. Furthermore you will want to be using deep-cycle marine batteries (~$90 canadian last time I bought one) not car batteries, as car batteries are not designed to be drawn way down and become damaged and 'die' that way.

To make your system more practical and do-able, the first thing I would ask is why on earth you want to keep the area at 40 F?! That is WAY WAY warmer than any chicken needs, even something big-combed and not cold-hardy. Seriously. If you have, in the past, gotten frostbite at temperatures near freezing, I will bet you dollars to donuts that you had most or all ventilation openings closed off in a reasonable but counterproductive attempt to keep heat in -- in well ventilated *dry* air, you don't get frostbite til much much colder.

Secondly, insulate the bejeebers out of the area, walls and ceiling both. 6" (well, a six inch stud wall, so that's really 5 1/2") of insulation on the walls, and double that on the ceiling, will allow you to use minimal wattage on whatever electrical appliance I cannot talk you out of using <g> and thus you will require much less battery-bank capacity.

Thirdly, consider building something like a solar popcan heater or the like to get as much supplemental daytime heat as possible.

And finally, you are STILL going to need multiple deep-cycle batteries to keep much wattage of light going overnight, and charge them up probably every single day. So if you can work out a system which does not require you to have so darn much heat, you would be far better off financially as well as practically

(e.t.a -- btw, if you know of a way of putting a timer on a battery-run device, please post a thread on it as there are quite a lot of BYCers who would like to know how, not for heat lamps but to run a 20-40w bulb for a few hours a day for winter lighting for eggs. I assume there is some way to do it but nobody thus far has come up with it, that I know of, and it would be really good to have a thread explaining how to do it!)

Good luck, have fun,

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Why do you need 40F? Not even seramas need 40F and they are the most sensitive to temperature of all the chickens. Even they will do fine down to 20F. All other breeds should do fine down to 0F. Nearly all standards and some of the fluffier bantams with flatter combs won't even notice -20F. My standards were standing in the open doorway of an uninsulated, not heated coop during our -30F plus windchill we had last year. They didn't care.

There are several thermostatically controlled outlets. I have one that comes on at below 0F and one that comes on at 20F and off at 30F. You can find them all over. I got mine off .

There's no way you are going to get to 40F on a -20F night with battery power and without an actual heater unless you completely sacrifice ventilation which is worse than them getting cold. Even my space heater didn't get my coop that warm and it kept flipping the circuit breaker cause I was running off a 300' extension cord. I ended up moving my 5 sensitive bantams into the house for those really cold weeks. This year I'm putting in a small bantam coop near the house so I can run my heater effectively to at least keep it at 0F preferably 20 for the seramas but I'm questioning getting it that high. As a backup we covered the screened porch in plastic and I can definitely get that up to 20. If nothing else I'll open the window to the house and add heat that way.
Our "coop" is a 11'x22' open rafter insulated "house" with insulated crankout windows and a functional coupola. There is a 12" sand floor under about 6" of pine bedding. We do not live there yet. We are building. I can't be there to change frozen water multiple times a day or collect eggs more than once a day hence the "above freezing" temperature I am looking for. This is the first winter with chickens, the "house" is untested. If it wasn't for the water issue or the fear that my roosters would damage their large combs I wouldn't worry too much about them in the insulated house.

The light will only be on a few hours after dark on a timer and will be a small 13w compact florescent bulb. I've seen heat panels on shop the coop that are only 16w. Lets say I had this heat panel to warm just the roost area from dusk to dawn, a 7.5w aquarium heater to keep the water from freezing, and a 13w bulb running for 3 hours a day. Could that be done on a car battery, or two batteries together?
I used an online calculator and it comes to 24.67 total watt hours per day.

You have an error somewhere in your basic assumptions. The panel heater alone is almost 200 watt hours per day.


a) accept that a few eggs may freeze. (Not as many as you may think, if you can collect eggs in late afternoon. It actually takes eggs a considerable while to freeze, first because they start out at a temperature of roughly 100 F, secondly because they are in a nice fluffy deep insulating bed of shavings, and thirdly because they do not actually freeze til, I forget, it's something like 27 F or so [internal egg temperature, that is]. And if you lose a few eggs, Oh Well.

b) use a largeish container (bucket style), make a well-insulated housing for it, and float something on part of the water surface. This should allow you to water them only once a day. Also you might look at the thread discussing the possibility of rigging a solar-powered water heater using an aquarium heater sealed into a water-filled base for a waterer (nobody's tried it, but it might be made to work with a bit of fiddling)

I've seen heat panels on shop the coop that are only 16w.

Yes, but you will only get 16 watts of heat out of it
That might be meaningful in a 2x4x18"h little tractor; it will be absolutely useless in your coop.

You get out what you put in. No way around it. And it would take a LOT of heater, I'm going to say in the 500+watts range depending on your insulation, to get your size coop anywhere *close* to the temps you want. Sorry, but physics is a harsh mistress

But as I say, there are other simpler ways to solve your basic problems, so I do not think you are really in any sort of a bind.

GOod luck, have fun,


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