This is great info. I have a thread that I started about this same subject. I will piggyback onto this one and ask a few questions.
It appears to me that people are either using the relay method or battery combiner. I don't see alot of folks using a pure isolator between the AUX and Starting battery. Why is that?
I have had a dual battery setup in my boats since 1989 and have always used an isolator without any problems. I am now installing a three battery system in my X30. Two Optima Blue Top D34Ms wired in parallel for the stereo and a single battery to start the engine, run the gauges, ballast pumps, bilge pumps, etc...
Here is my block diagram.
Can someone tell me if this looks correct?
2002, X30, L-18, Red Metal Flake (the possessed boat)