Sharing a maintenance item some may have overlooked (I sure did).
I've spent some time building out my 12v setup. I'll share an observation:
- With stock terminals, I noticed my alternator charging voltage was fluctuating from 13.3-13.9.
- With new mil spec terminals (pictured below), my charging voltage holds steady at 13.8-13.9.
My old battery terminals were old and corroded-- I suspect this was causing a poor connection the the battery. I didn't do a full "big 3" upgrade because the Mil Spec terminals gave me flexibility to wire directly to the battery.
You probably don't need to go as far as I did. I assume even a proper cleaning would have made a difference.