Instead of thinking of this as “drain”, could this be some recalibration impacts happening in more real-time? I say this because I experienced the opposite effect. Yesterday I arrived at house with 48% and 3-4 hours later I was at 51%. Never seen that before.
If you park and the SOC inreases it is most probably/most certain coming from a adjustment on the SOC after the car has been sleeping a while. The correct SOC can only be measured during sleep, after a while.
The SOC is determined by the cell voltage.
During a drive the car use the last known SOC and reduce it by subtracting the used energy to estimate the SOC. I
n some cases, like having an underestimate on the battery capacity, the on screen SOC os to low because of the maths from the underestimate.
When parking the car goes to sleep (contactors opens and the battery rests, showing the open circuit voltage, OCV). The cell voltage shows a higher SOC than the estimated and the car update the SOC.
I have seen this often as my BMS is a bit off at the moment.
Loosing SOC after a drive is possibly the same issue.
I see in teslafi that the average range for for all cars has increased about three percent from a very stable level an I feel a bit sceptic that the real range is at that level in average. My guess is that tesla changed the software to estimate higher capacity/range for *some* reason and that the capacity might be overestimated.
This could make some cars loose one or a few perfent after a drive, but only the first hours after the drive and only if it was a longer drive (short drives do not cause a noticeable difference of the estimated and real SOC.
Seems like most cars here continue to loose range, like the car wasn’t sleeping.
I parked (2022.24.6) with 26.00% tursday evening one week ago for two days (44hrs) and took the car with 25.67% on thursday evening.
Also parked with 80% on friday evening until sunday and had 79.63% on sunday.
(Never usually leaves the car at high SOC, but it was outside with very low ambient temps and cell temp between 8.5 and 4C during this time). Felt crazy to leave it at 80% but I survived
