OK, so I got my 40lb thrust Minn Kota trolling motor and in the manual it says nothing more than a 100AH battery is suggested. But I looked into that, and they suggest that for ALL of their 12v trolling motors. I've been looking around and some batteries list AH, some don't. Some are $300 and some are like $80. Some only list "reserve capacity". When you search these things online you get answers all over the place. So what I'm looking for -- a battery that I can take out and run for 2-3 hours. I know I need a deep cycle 12v battery but what all the numbers mean in relation to the longevity of hte run time is beyond me. Anyone have any experience and generalizations of what to look for? Any recommendations on where you buy your battery?