Here is a post I had last year.
http://www.iceshanty.com/ice_fishing/index.php?topic=29928.msg286177#msg286177I put this fan in but didn't get a chance to try it out yet. Hopefully we will get some "@#$%!*" ice this year!!
I got a "AA" battery holder from Radio Shack for a couple bucks and wired a small toggle switch to it and it seemed to work OK.
I am not an electrician by any stretch of the imagination so I don't know how long it would actually last on 2 AA batteries but I only want to run it for short periods of time to vent the shanty.