Battery level decrease and increase while parked

[Frans928]

Battery level of my S 90D 2016 usually decrease few % per day, unless it passes 12%, then decreasing 1% per hour until 5% while parked. Then charging until 80%, charching stopped and next hours the level increase until 84%.
Anybody has explanation for this phenomenon?

 

[ucmndd]

No explanation, but I see similar behavior. If I park my car at a state of charge less than 15% or so it will rapidly “lose” about 5% over the next several hours. Then charging will start, it will charge to the set limit, and at some point after that the BMS “finds” the missing 5% and the state of charge jumps to ~5% above whatever I set the limit to.

I’ve written it off as a quirk of a 5 year old car with 130,000 miles. It doesn’t seem to affect anything.

 

[Cheburashka]

Yes, same behavior with my 75D

 

[JohnRamboJedi]

Noticed this as well on my 2016 P90DL. If I park below 10% and leave it for a few hours, it will lose 5-6% all at once. Then when I charge back up to say 80-90%, It will find the 5-6% again. My working theory (I can't prove it 100%) is that Tesla uses the 4 or so kWh of buffer below 0% as just that when the car is newer. But as the car ages, they incorporate that below 0% buffer into the actual range. So all in all, I think any one of us would not have much of a below 0% buffer on our cars anymore. I don't really want to test that out though haha but just a working theory on this.