Not a bug

Charge state end -- rounding down?

klynde 2 years ago updated by StefanSarzio 2 years ago 6

I've noticed that the last two times I have charged my Model 3, TeslaFi records my end SOC as 1% BELOW the level that was set.

For example, yesterday, I set the charge limit (in TeslaFi) to 55%, and it recorded the end charge SOC as 54%.  Today, I set it for 80% and it recorded 79%.  First time in hundreds of charge cycles (across two cars) that has happened,. One consequence is that I have seen a sudden spike improvement in the Battery Reoort, which I realize is probably the result of dividing the Ending range by a smaller End charge %.  Here are the numbers from the battery report:

I made some changes to the battery report to use the charge limit settings if the completed charge level is one percent below it.

I also added some debugging data in the 'Included Charging Points' table.  It will show the charge percent and adjusted charge percent if the charge limit was used instead.  To easily find something that was adjusted you can scroll through the charge difference column to see any points besides 0.

I think this will work but let me know if anyone see's anything weird.


Hopefully this will be resolved in a new firmware release.  In the meantime, I've added the ability to edit the ending charge percentage of a charge.  If you click on the edit button to the right of the charge record from the main index page you will see the new ending charge % field.

If they don't resolve it I'll look into a more permanent fix.

The API is reporting you stopped at 54% and 79% for those two charges.

For sure, James, but the point is that the charge limits were set via TeslaFi at 55% and 80%, respectively.  This appears to be a change in how the firmware in the car handles a request for a specific charge limit: it charges up to but not necessarily including that requested SOC.

As I mentioned in the original post (I posted that one under my wife's name), it causes a distortion in the battery degradation report.  Take a look at the jump in Estimated 100% charge that happens AFTER the firmware upgrade before the last two charges:

Not much you can do about it, since the API reports 79.999% charge the same as it reports 79% charge.

Not a bug

Yes, it doesn't appear to be a bug with TeslaFi.  The API is reporting you stopped at 54% and 79% for those two charges.

The detail of the 79% is:

From the detailed view of the charging session I can see that the car indeed stops right when reaching the charge limit - so e.g. when SoC switches from 89% to 90%. It then often falls back.

Previous to 2018.42.3 it would still charge at the configured limit of 90% for a few minutes - like on every other percentage value.


This was reported on TeslaMotorsClub.com as a possible bug in firmware 2018.42.3.


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