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Charge limit exceeded AFTER disconnecting

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MarcG

Active Member
Oct 29, 2014
4,307
6,250
San Francisco
I set my daily charge to 90% and usually plug in every two or three days at work during the week. Today, I charged from a little under 40% (92 miles of rated range) to the usual 90%, which got me to 225 miles. Charging stopped by itself, and VisibleTesla confirmed I was a 90% and 225.02 miles of rated range.

After a few minutes of getting the notification of charge completion, I went out to the parking lot to unplug. After unplugging from the charger, I got in my car and immediately noticed the car reported 227 miles of range... "strange" I thought, the only time range goes UP while stationary is when I change RANGE MODE from ON to OFF - however, I've kept it ON for several months now.

I then opened the charge status page by tapping on the battery icon at the top-left of the screen, and sure enough: the battery level was OVER 90%, with the line showing the current capacity to the right of the caret indicating charge limit, which was directly under 90%. Unfortunately, I didn't have my phone on me at the time to take a shot of that screen.

VisibleTesla confirmed my suspicion: the battery level showed 91% and the rated miles was at 226.72, up from 90% and 225.02, respectively. Also, the graphs do show an increase in rated range several minutes AFTER current and voltage dropped to 0.

Glitch in the charging system, or firmware/software bug?


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My guess is that its temperature related. Remember that the miles and SOC% values are estimates, its not like measuring or weighting something. There is a software algorithm that makes an estimate based on current battery voltage, past draining curve while driving (miles driven with power consumption vs voltage drop over time).

So my guess is that the car charged to 90% (100% in the case of islandbayy) then stopped. Some time later the algorithm adjusted the % value (and rated range) above the 90/100 % because probably of a temperature related effect of voltage and it triggered the message. Tesla might adjust that trigger to increase the threshold if it happens frequently...
 
Something similar happened to me a few months ago. I would charge to a certain level, say 228 miles or 90%. Then, when I turned on pre-cooling, the range went up by 3 miles to 231 miles, simply by pre-cooling the car. It did that for a while - couple of weeks - but the behavior eventually stopped and I can no longer reproduce it.