Ah, found the post:
maybe this was described in the paper or before in the thread, but I cannot recall I have seen it. So if they are not sure they are reading voltages correctly, how is it that they know reliably it is charged to 4.2v? or potentially not? I know there was a discussion about "not-existing range" at...teslamotorsclub.com
Now, doesn't this mean that on pre-2015 contactors stay closed and 12V battery is charged with the "regular" DCDC? On post-2015 contactors are open and MCU is powered from the standby DCDC..
Anyway, I'll measure how my 12V behaves on 2013 car..
Yup. Good catch. I mis interpreted what @wk057 said initially and it explains an unsolved mystery.
When I first got the MCU2 upgrade, my vampire drain was higher than before. I also noticed that my 12v battery was constantly being charged and realized my contactors were never opening. When coming to the car after sitting for hours, opening the door did not result in the normal clackity click noises from the contactors closing. Hence the reason I started this thread. I assumed that it was because the contactors were staying closed all the time and it turned out it WAS the reason hence my increased vampire drain.
I then got those BMS errors and took it into Tesla. They said my HVL nodes were misconfigured and they corrected them. Later I reported that my vampire drain was higher after the MCU2 upgrade but then I turned Teslafi polling off and the drain dropped to pre-mcu2 upgrade levels. Well it turned out not to have anything to do with that at all. What made the vampire drain lower was them fixing the HVL node configuration to properly use the standby converter. So after I got the car back, my vampire drain was lower but I thought it was because I'd turned off Teslafi polling.
So this morning I verified that when I open my door that the contactors are indeed clicking closed as they used to do before the MCU2 upgrade.