have a question if i would add a 2nd trolling batt to the one already instaled in the boat would you go with a equal size battery and since it is a 12 volt trolling motor that would be hooked up pos to pos and neg to neg that would keep me at the 12 volts correct .

what is the result of that,, a longer trolling time ?
and if i would happen to buy a on board charger would i still have to get a 3 stage 1 for starting and 1 each for the trolling batteries .

thanks,
Scott