I would and I do run 2 deep cycle batteries for my trolling motor, and 1 cranking battery for everything else. They do make deep cycle starting batteries but they have less capacity and charge slower since a deep cycle battery is best suited for a trickle charge. In saying this if you fish all day without starting your big motor frequently you may find yourself with a dead starting battery when it is time to go home. This would be similar to listening to the radio all day without starting your car.