Awesome. I edited my above post to add this:Hot damn - thanks.
I reset the battery sensor, and now the battery seems to be charging at 13.5V (previously 12.0V).
Also, you're correct on charging. Page 495 of the manual clearly warns customers not to use the negative battery lead for anything. Instead, use chassis ground - and there seems to be plenty of chassis ground connections within the engine compartment.
Appreciate everyone's comments on this one. Several lessons learned, and I can imagine most other Raptor owners would benefit from this thread. I'm viewing this as "solved" for now, but will report back if I see the error again.
Thanks again
“Last thing I did, after resetting the sensor was to let the truck sit locked for over 8hrs. Manual states it takes at least 8hrs, without being woken up for the system to fully calibrate.”
Manual states this, which you may have done already. But good info to point out for anyone having issues. I know there was reports early on of dead batteries/low power mode.
Edit: and @FordTechOne beat me to it again by a few minutes. Haha