I'm looking for an electric fence solution that is battery-powered and small. Very small. As in, I have a chicken coop which is about 8'x16', and I want a perimeter fence to run around the base of the portable coop that is battery-powered to fend off varmints. Has anybody seen or done anything like this? It would need to be relatively cheap, since I'm thinking about using this solution on potentially dozens of such coops. Thanks!