Um. Yeah. 12.5 - like any new battery. Really, not to disparage any of you but, were it something straight forward, I'd have figured it out. May be a bad cable. though the cable was fine an hour earlier - but, perhaps manipulating it in the 23F cold caused something to come undone.
I guess that a more interesting diagnostic question is whether, if one of those 50 or 100 amp fuses go, does is cut all power to the car?