In between my experiments with an automated coop door, I made a simple LED coop light. Now, I dropped the plans to extend daylight since the chickens are still laying even with the short days. They're a bit inconsistent: some days three eggs, today only one, but I want to see what their natural response is before I try to change it. And to be honest, with almost 5 dozen eggs sitting in the refrigerator (even after giving lots away!), I don't really need to increase production.
Anyway, I do need a light when I go out there after dark to lock things up and check on them. Since there's no AC power out there, I rigged up an efficient light using six standard white LEDs and the 12V lead-acid battery that will eventually also power the auto-door. Works great! There's more than enough light for me to see: in fact when I turn it on, the ducks usually come over to see what I'm doing and the chickens start getting down from their roosts. Back of the envelope calculations are that it could run continuously for about 3 days on that battery, so the 2 minutes/day I use it should be no problem at all. It'll be interesting to see how the battery fares when the temp consistently drops below zero!
I'm considering making this a standard product over at the site so let me know if you're interested. Tentative price is about $15-$20 for the 6-LED light fixture, just needs a 12 volt battery to run.