Hey I just bought my first boat; it’s a 79′ 17 foot sylvan aluminum boat with an 85′ 75 horse mercury and a 12v 42 lb minnkota autopilot. I generally use the trolling motor when on the lake, and the engine when on the river. I am planning on buying two batteries, one for starting the engine, bilge, and live well. The other battery would go up front for the trolling motor. I will be doing a lot of river fishing this summer as I am moving back to grand forks. But I will take a few weekend lake fishing trips as well and would like my trolling motor batteries to last 2 full days of fishing.
My fist question is, is it a good idea to wire the two batteries in parallel to extend the battery life. I ask because I could wear down both batteries and have to paddle back to the ramp? Secondly would it be better if I had a disconnect switch so they were only in parallel when needed?
My Third question is should I just get 3 batteries 2 in parallel up front for the trolling motor/accessories and one on its own for the engine?
Any answer or comment is appreciated.