Is your trolling motor 24v or 12v? My boat has a 24v trolling motor. Everything else on my boat is ran off of my cranking battery. Thats lights, electronics, pumps, ect. Everything that is 12v. I have a 3 bank charger. Charges both trolling motor batteries and my cranking battery. I go fishing and when I come home I plug my boat in. My cranker is also charged when I run my big motor but sometimes that is very little. When you have 2 gps on, livewell, and lights it can put a strain on your cranking battery. Thats why I charge it after every use. Some people don't and never have a problem.

I have a dual pro. I hear alot of good things about the Minkota chargers also. Guest is another good one. I have heard alot of horror stories about Dual Pro but I have had no issues.