Re: Extra Power
I have a 55 pound thrust MinnKota Power Drive on my 18 footer. In my opinion you need at least a 50# - 55# motor. Anything bigger than that will require two batteries in series since they require 24 volts.
As for hooking the troller battery to the charging system, that would depend on if you us the troller for fishing or stricly for backup. If you use it for fishing there is no sense hooking it to the engine charging system. Trollers draw a great deal of power and therefore require a deep cycle battery. A deeply discharged battery would require hours of wide open throttle running to charge from the small alternator on the engine. If it is stricly a backup power source, then yes, you could interconnect the two batteries with a battery switch or isolator. My honest opinion, if you are less than a mile away of the dock forget the motor entirely. You have a cell phone. Call someone to come get you. It's cheaper.