Bownarrows

I am having an issue with my boat. I have a 55 edge Minnkota trolling motor on a 12-volt battery. The issue has just start where my trolling motor will run normal for and little but then during operation with foot on the button it will stop running and then come on for a couple seconds then back off. If you don't use it for a couple minutes, then use it again it will function normal for a little bit... It does this at all speed setting... Then is you keep the button button pressed when it does the short bursts it will just continue the short bursts,,,, Last night it stops completely and had to let it sit for a few minutes before it would function again at all. This is driving me crazy. I have two used trolling motor of the same kind and both are doing the same thing. I have added another battery still the same thing. Need some guidance please. Has anyone seen this before???????