Quote Originally Posted by bsell
Sounds heat related...did you check all of the other connections/wires back to the battery to include cleaning all of the grounding points?

I wonder if you have a rotten cable running along the floorboard from the engine to the battery that gets hot and resistive over time. I swear I've seen this kind of mess before and finally found it by flexing a positive cable and hearing the crunching noise from the corrosion under the insulation. To look at the wire, you wouldn't have suspected it was garbage but once I cut the insulation off of it, what a mess!

You can find the culprit, you just have to hang in there and be thorough in your search.
If you're checking your voltage while running through the OBC are you sure your fusibile link is in good shape?

Heat would cause this to go funny...