Car consistently says 2-3% more charge is added after charging

[Benito1283]

I usually charge my car to 65% and start charging in the 50-60% range. Nine times out of ten, shortly after it’s done charging it will say the charge is 67%. Occasionally 68%. I understand the effect of ambient temp on SOC and that’s not what’s happening. If I watch the percentage as it’s charging, it will stop charging within 5 minutes of reaching 65% as expected.

I have a longer drive tomorrow so I charged from 60% to 75% today. Charging completed at 75% and showed 239 miles. Ten minutes later it’s showing 78% and 250 miles. Like…which is accurate?

It doesn’t really bother me because I assume there’s no ‘real’ issue. Just curious if anybody knows why.

 

[jcanoe]

It is just the Tesla battery management system (BMS) having difficulty estimating the precise state of charge of the battery. You can help by periodically charging to ~95% and the driving until the battery state of charge is below 30%, This will provide the BMS with more data points for the algorithm. Also, turn off Sentry Mode and Smart Summon (if you have purchased FSD) when parked at home (do this at least some of the time) so that the Tesla Model Y will enter sleep mode. The Tesla BMS can only measure the open cell voltage (OCV) of the cells in the battery when the battery pack is disconnected from the vehicle, as in sleep mode.)

 

[Benito1283]

It is just the Tesla battery management system (BMS) having difficulty estimating the precise state of charge of the battery. You can help by periodically charging to ~95% and the driving until the battery state of charge is below 30%, This will provide the BMS with more data points for the algorithm. Also, turn off Sentry Mode and Smart Summon (if you have purchased FSD) when parked at home (do this at least some of the time) so that the Tesla Model Y will enter sleep mode. The Tesla BMS can only measure the open cell voltage (OCV) of the cells in the battery when the battery pack is disconnected from the vehicle, as in sleep mode.)

Interesting. Thanks for the explanation. I don’t use Sentry or Summon. I’ve gone from 95% to ~20% a handful of times over the months. Not sure it helped but I’ll pay closer attention next time I do.

 

[jcanoe]

Interesting. Thanks for the explanation. I don’t use Sentry or Summon. I’ve gone from 95% to ~20% a handful of times over the months. Not sure it helped but I’ll pay closer attention next time I do.

That is fine. Some Tesla owners never exercise the high voltage battery beyond a narrow range of state of charge.

 

[CaseyL]

I usually charge my car to 65% and start charging in the 50-60% range. Nine times out of ten, shortly after it’s done charging it will say the charge is 67%. Occasionally 68%. I understand the effect of ambient temp on SOC and that’s not what’s happening. If I watch the percentage as it’s charging, it will stop charging within 5 minutes of reaching 65% as expected.

I have a longer drive tomorrow so I charged from 60% to 75% today. Charging completed at 75% and showed 239 miles. Ten minutes later it’s showing 78% and 250 miles. Like…which is accurate?

It's not unusual. I charge ours to 63% daily because it typically drops about 3% after charging. I just got used to it. After I drive 25 miles to work, it usually bumps up about 2% in the next 30 minutes.

 

[Calliope]

You can help by periodically charging to ~95% and the driving until the battery state of charge is below 30%, This will provide the BMS with more data points for the algorithm.

Interesting! I notice too occasionally I get a (standard) message saying charging as stopped at 80%, but when I get in the car 6 hours later, it's at 82%. I figured temperature change, and never worried about it. But this is also interesting information.