Just wanted to provide some input on 12V battery monitors:
While it may not be the go-to tool in assessing the health of your 12V. It can certainly help diagnose unusual behaviour which are signs of a failing battery. I've been having all sorts of sleep/wake issues where the car is waking up 100 times a day or so since Feb 22 (there was no update installed the day before to trigger this) . I dont have a single 3rd party accessory or 3rd party apps connected, and all the usual features that keep the car up have been disabled.
You can read more about my issues here:
Model 3 Multiple Issues
While it's not yet proven that my 12V is causing the issue, I recently installed a 12V monitor only to see all kinds of voltage drops and spikes. It seems like the car has been frantically waking/sleeping to keep the 12V topped up due to rapid discharge of the battery. It is either a sign of my 4 year old original 12V failing, or abnormal parasitic drain from a software bug/faulty hardware component.
What's more interesting is this issue arose when the car had been left for 4 months, only being charged as the HV battery drained. From a physics standpoint this is in line with a use-case that would cause sulfation as the car wasnt waking up long enough to free sulfate build up.
Do you think this makes sense... I've been troubleshooting for months now so I tend to tunnel vision when things add up like this.
Here is what my graph looks like (the periods where it holds voltage indicate not sleeping, or a drive:
View attachment 813858