With my Minn Kota RT55/ST/iP running at lower speeds utilizing the Digital Maximizer I get 10-20 hrs runtime from my 2 DieHard Platinum (AGM) Marine Batteries - group 34M (3 year warranty) which works out to about $4 a day @ 30 trips per year! For fishing the GPS Spot-Lock (invisible anchor) is so very sweet - you never move more the 5 feet regardless of wind, current, or depth - great for hovering over reefs and wrecks.
On the other haka goes a Scotty 1106 to get down to the hoos in the heat.
Only one downside - WEIGHT!
That's why I'm selling my 2013 hardened AI and shopping for a TI 2012 or newer!http://miami.craigslist.org/brw/boa/4430738690.html