When it gets cold this winter, i'm afraid my water will freeze everyday. The coop has no electric, and I don't want to run a chord across the yard for a heat source. I have a 3 gallon waterer that usually lasts for a couple of weeks. Are there any options, other than giving them fresh water everyday. Is there such thing as a battery powered heat source? It is a small coop so their body heat may keep the temp above freezing. I'm just not sure. This will be my first winter with chickens. Please help.