bucky, corrosion will happen everywhere. That includes in between contact surfaces. I would take the connections out and check them for corrosion, you know, that white/greenish powder. also check the connectors and where the cable gets in the connector. You are better moving everything off your cranking battery other than the motor itself. You can balance your load between the 2 12v batteries for your accessories. Electronics attached to a motor risk getting damage by both low voltage and high voltage spikes during cranking and WOT. Does it happens to everyone, probably do and they dont realize why but why risk it, it will probably be a cable swap or at worst case you will have to add longer jumpers.

Good luck!!!!