Oh wow! I turned the vehicle on and trapped the BCC with a hammer, as if it were a small starter. There was no clunk that occurred (the clunk was always heard with the key rotated to the "on" position) but the house batteries started charging at 13.3 , the left side of both main connections to the BCC jumped to13.4, and both right side BCC terminals jumped to 13.7. Lastly, the vehicle battery was charging at 13.8.
Before I claim victory as a potential diagnosis of a tired BCC needing replaced, I need to be sure that I run a few more tests to ensure this wasn't a function of vehicle run time or pressing the aux start.
I've tried the aux start and time method in the past, so I feel those are ruled out as fixes, but I feel as though if the tap method works, then I will need a new BCC cylinder thing (insert technical name here).
(Finger pointing you technical thing)Attachment 280861