I have been fighting phantom drain for a week or so, and finally managed to get it under control. Heres what i have learned.
My phantom drain was around 1 mile range lost per hour whenever the car was parked and not plugged in.
I had been using the tezlab app to monitor, and then added teslafi as well to try to figure out what is going on. Teslafi gives the detail i needed to figure this out - it basically tells you whenever the state of the car changes (i.e. between drive, park, sleep, charge).
At first teslafi showed that the car was not sleeping at all, which i guessed was the root of the issue. So, i disabled tezlab (by removing the app, and changing my Tesla account password), and avoided opening the Tesla app altogether (still running in background for locking / unlocking). According to Teslafi, the car still did not go to sleep, and the phantom drain was still there. So i started playing with the polling frequency in the Teslafi settings. The default is 1 minute, so I set it to 30 mins, and after a few minutes, sure enough, the car did go to sleep, and there was almost zero phantom drain while in sleep state. Yay!
But, the problem now is if I go on a short drive, less than 30 mins, Teslafi may not realize, and count that loss as range loss during sleep. So, I experimented to find what is the smallest poll frequency that still allows the car to sleep. The answer is 11 minutes. So I am guessing the car waits 10 mins after parking before it goes to sleep. Setting the poll frequency to anything less than 11 mins and the car stays in Park status. I still have the issue that if I go on a short drive less than 10 mins, Teslafi may not log that drive, but at least I cut my phantom drain to almost zero.
I am now wondering why the car waits 10 minutes before going to sleep. There is no perceivable user experience difference when unlocking the car from sleep state vs parked state - the car still unlocks instantly when I press the door handle, and the car wakes up immediately. It would seem like it would be better all around if the car went to sleep immediately when it is locked. That way I could set my polling frequency back to 1 minute, and not miss logging any drives in Teslafi.
So, the key takeaway for reducing phantom drain is to make sure the frequency with which the car status polled, either by the Tesla app, or any other 3rd party app or service is not more frequent than every 11 minutes.
Anyone else experienced this?