I think the battery terminal connection on one battery was loose, and the reason it was loose was too darn many things going right to the battery terminal itself, vice going to a good terminal strip where each item can be well tightened down.

I have removed a few connections that did not appear to be doing anything and have added split lock washers to the terminal itself to keep what is there properly locked down.

I had no idea of a loose connection until I pulled the batteries... I had to pull batt 2 to get to batt 1, and batt 1 was where the poor connection was. Meanwhile, since everything was out of that tiny compartment, I was able to peek around and follow wires to their ends and determine what was what... and in doing so, I removed some items that went no where.

At this point everything is tight and working fine, but I want to clean that area up more and use a distribution (terminal) strip for connections vice running everything right to the battery. I also believe some cables need to be better supported so they are not damaged by vibration.

I tested the batteries and they look good... specific gravity was good, and load testing was good, so the problem had to be somewhere else.... which was back to the loose connection.