Just run you a wire from positive to positive and one from negative to negative. Just dont run your trolling motor so much that its runs the batteries down to weak to crank your motoe when you are ready to go. I would reccomend an on board charger. Just plug it in when you get home and unplug before you leave. You'll always have a full charge on your trolling battery when you leave. I just ordered a 3 bank on board charger for my boat, but I always charge my batteries every time I get home and top them off the day before I go fishing...Rather be safe than sorry!!!