I use a minnkota auto pilot 55# thrust 12v run it on 2 12 volt batteries hooked parrallell will last daylight to dark trolling at 1.0 mph
Speck
Real men troll for crappie (Here Fishy Fishy !)
I have a three year old Minnkota Riptide 65 AP with the Co-Pilot module.
It is powered by two (24vdc) lead acid group 31 batteries that I charge with a Pro-Mariner Pro-Sport on-board charger.
I use the motor for 8 to 10 hours at a time. When I am crappie trolling, it normally runs at 10% power, but when I am striper trolling, I run it at 80% power.
The trend in marine batteries these days is going the AGM route.
AGMs are much better for marine use. They can take the pounding and vibration that batteries get from being in a boat.
These batteries are also completely sealed and maintenance free.
The AGM technology allows these batteries to be used as starting batteries or deep cycle batteries.
The Cabela's line of AGM are very popular.
When my group 31s give up the ghost, they will be replaced with smaller more powerful AGMs. They are a little, but you only live once and I ain't skimping on my fishing!!