My problem is my back. I have a small fishing boat that I carry in my pickup to my favorites ponds and lakes, but my battery is too heavy for me now.Can I buy and use a small tractor or lawn mower battery for my trolling motor? I only need it to get out a little and then I stop and fish. I wouldn't be using it for long periods of time. Thanks for any help on this I have oars in the boat also.