Suggestions for a onboard charger dual bank. I would like a built in alternator, waterproof. It also needs to be able to figure out/able to charge two different types of batteries, one deep cycle one cranking, at the same time. Also do they also have a ac connection to charge them? I have zero experience dealing with on board chargers. Would it be better to add a third battery? One for cranking, one for trolling motor and one for everything else? Icurrently have a basic charger and it gets annoying not being able to charge both batteries at once. What would you suggest? Thanks in advance!