I have a 17.5 feet bass tracker with a 40hp motor. Trolling motor is a 12 volt Terrova. I use to have two dedicated batteries for the trolling motor. They lasted almost 6 years. I had two because I use to troll a lot. Now I only spot lock around structure for crappie. One battery I took out and have just one now. I am doing a battery recondition on it to see how much more is left. I had 2 group 29. I can only find group 31 or 27 in marine deep cycle. Question is I think one group 27 will do for just spot lock use any thoights?

Thanks