Is you TM a digital product? I went with a 55lb digital, variable speed (1-10 setting) 12V MG on my 17'6" G3 tin and it is really energy efficient, I do not run around all day with it on 10, only to change locations of 100 to 200 yards. I never run out of juice for a 5-6 hour day on the river. The battery is a Deka 27, 575 CCA,705 MCA@32degrees, 20 amp AVE 200minutes.