I want to keep an open hole of water on a 1-2 acre (approximately 10� deep) pond for waterfowl. The pond is too remote to have access to electricity. I�m looking for (inexpensive) ideas for a de-icer system that would last for a few days without maintenance (i.e. recharge batteries).
I have �experimented� w/ a trolling motor lower unit attached to a portable metal stand which created a 10�X20� hole outta� 4� thick ice by �directing� warmer water to the surface. The problem was the small marine battery only lasted 2-3 hours before runnin� out of juice.

I�m planning to purchase a couple of large marine deep cycle batteries to provide the system w/ extended longevity, but I don�t know how to properly
wire multiple batteries for this purpose. Also, I think I can double the battery life by using a flasher timer, but don�t have any idea how to set up this system. Any ideas, thoughts, etc. would be appreciated!