I recently bought a minn kota Terrova 55 Ipilot and now I am thinking of adding a starting battery and a multi-bank on board DC charger. Why? Well Minn kota is very adamant that the battery bank used for trolling motors is not used for anything else because fish finders using the same batteries as the trolling motor will display interference. I don't know about the trolling motor, but I do see a lot of static/interference on the fish finder when running the outboard at higher rpms. I assume what I see is electrical interference from the outboards alternator since it is connected to the same batteries as the finder. Is this correct? This is causing me to consider my options for isolating the systems/batteries.
I currently have two 29 size deep cycle batteries running parallel for 12v power which powers everything in the boat... outboard starter, fish finders, lights and trolling motor. I am getting much better run time out of the two battery bank than I ever did with a single. It's also less taxing on the batteries because I don't run them as low as I would a single battery. I do know however that using deep cycles to start motors is bad for the battery.
All of my systems will be 12v. I'm wondering if I should leave the trolling motor, lights, and fish finders on the parallel 2 battery bank, or split the trolling motor on one battery and put the finders/lights on the other single battery. I'm thinking that isolating the systems between the 2 deep cycles and the starting battery is the best bet, but I like having two batteries run the trolling motor. Or should I get a multi purpose deep/cranking battery to run the fish finder and starter and keep the two battery bank for only the troller?
What are the pros and cons? Any tips or tricks? Thank you all in advance.