I was wondering which battery would be the best one for trolling and from the research that I came up with was the Delco voyager series, im not sure what the cost of these things are, but seem to be made especially for trolling and long periods of drawing power from the batteries.
If you want, here is a link where you can read a littel about it, read the Choosing A Battery section on this page, and the second link is from the ac delco website. Good luck with your issue.
http://www.activeangler.com/articles.../batteries.asp
http://www.acdelco.com/parts/battery...er-battery.htm