Battery Does Not Charge to Selected %

[George I]

I set my S90 to charge to 80% unless I'm going on a long trip (100%) or am going to be away (50-70%).
After doing some road trips (where I will sometimes charge to 100% and/or take the battery <20% [occasionally <10%]) I have noticed that when I get back home and set it back to its usual 80%, the car will often not charge to the set amount. I am not talking about 81% or 79% when you set it to 80% but 86%, 77% and other percentage that I do not have a picture of. Car was plugged in, slider was not touched after setting to 80%.
This 3.25yr old car had lost a bit of range in the first 6 months of ownership but has been pretty stable around 443km ever since. Supercharges at >110kw before latest update (have not had chance to supercharge since 2019.20...).
Does anybody have any ideas of why? Should I be concerned?

?

 

[Tam]

...concerned?...

I don't think so.

Percentages are dynamically translated into miles so their numbers are different over times.

Percentages are also dynamically calculated so their numbers are also different over times.

To minimize the inconsistency, the calculator demands full 100% and depleted 0% so it can calculate but that's not good for your battery health so it has to guess each time you don't wear your battery down from 100% to 0%.

The compromise is for owners to set the maximum charge at 90% daily.

However, if you set your charge less than 90% regularly, the calculation would drift more and you can see the more inconsistencies as you experience above.

So after your car has a taste of 100% charge, it could then now recalibrate and your new 86% would now be your old 80%. So when you set your slider to 80%, it doesn't stop charging at the old 80% mark but stopped at the new 86% mark. From then on, when you set it at 86% it'll stop at 86% and set it at the new 80%, it'll stop at 80%.

The same could be said about your new 77% and old 80% mark. Once it recalibrates itself, it'll stop at the new 80% after that.

 

[ran349]

I set my S90 to charge to 80% unless I'm going on a long trip (100%) or am going to be away (50-70%).
After doing some road trips (where I will sometimes charge to 100% and/or take the battery <20% [occasionally <10%]) I have noticed that when I get back home and set it back to its usual 80%, the car will often not charge to the set amount. I am not talking about 81% or 79% when you set it to 80% but 86%, 77% and other percentage that I do not have a picture of. Car was plugged in, slider was not touched after setting to 80%.
This 3.25yr old car had lost a bit of range in the first 6 months of ownership but has been pretty stable around 443km ever since. Supercharges at >110kw before latest update (have not had chance to supercharge since 2019.20...).
Does anybody have any ideas of why? Should I be concerned?

View attachment 438857 View attachment 438858 ?

I don't think it should do that. Does it happen when you charge away from home?
Do the rated miles correspond correctly to those percentages?

 

[George I]

When traveling I never set it below 90% (to keep spontaneous detours etc available), I only set it back to 80% on coming back home.
Rated km do correspond to those percentages. When you take whatever percentage it is and convert to 100% max km the max range is pretty steady in the 437-444 range.

 

[Tslrsx]

My x also does that sometimes, after changing the charge limit a couple times( charging in increments of 10%) the car sometimes charges 3-4% over the limit. It changes back to normal after the car charges a second time to 90%(first time it charges to 92-93%).

 

[ran349]

When traveling I never set it below 90% (to keep spontaneous detours etc available), I only set it back to 80% on coming back home.
Rated km do correspond to those percentages. When you take whatever percentage it is and convert to 100% max km the max range is pretty steady in the 437-444 range.

It doesn't seem like anything that serious, but if it keeps doing that I would call Tesla just to see what they say about it.

 

[jerry33]

It sounds as if it's calibrated for a 100 rather than a 90, which is why it shows more than selected.

 

[Tam]

...80% ...

Depending on your goals, if you want to minimize calculation drift, you should regularly charge to 90%, and not less than 90%.