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Battery SoC exceeding pre-set limit?

Battery SoC exceeding pre-set limit?

I've had my MX since Nov 14, 2018. Last night I set a charge limit at 75%. At 11 p.m. I got the usual push notification that charging was complete (with 231 miles). The MX stayed plugged in all night, and in the morning, I noticed that the range was now showing 236 miles. Sure enough, the green charging indicator had passed the charge limit line, and my SoC was now at 76%.

I charge at home using the Tesla Mobile Connector on a NEMA 14-50. I had dialed down the Amps to 16 for overnight charging (max 32A).

I've never seen my MX charge past a charge limit and am wondering if this has happened to others? I couldn't find anything in the manual or online and am wondering if I should be concerned about this.

pandyarajen | December 26, 2018

I haven’t encountered that.

Any reason to drop current from 32 to 16?

dpm526 | December 27, 2018

My thought was lower amps would be better for battery health.

Same thing happened last night: set to 90%, woke up to 91%.

I sent an email to my person at the Bellevue SC and will see what he says. I’ll also try charging at 32 amps tonight and see if that solves it.

dpm526 | December 27, 2018

I might have figured it out, but haven’t confirmed anything with Tesla yet.

The day before it “overcharged” I got a “charge port door needs service” message. Under the “charging” menu in the app, it is showing that the MX has completed charging and that the charge port is locked, when in fact there is connected to the mobile connector. It somehow believes that the charge port is closed and disconnected even though it is plugged in and presumably getting at least a small amount of power.

I’ve already scheduled the service so hopefully that will resolve both issues.

jjgunn | December 27, 2018

Before you bring it into the service center....did you try a dual scroll wheel reboot?

Try that first....then charge & see if it happens again.

skip8jones | December 27, 2018

I would not worry about 1%. Remember there are a number of algorithms and all that are used to calculate these numbers. It may read differently with the next update.

ratchet | December 27, 2018

I have had that experience on my MX 100D. I start charging at 11 pm at 40 amps which usually completes charging (from about 50% to 90%) around 3 am. When I check status on the phone app at 4:30 am, it says charging is complete with range of 257 miles. When I get to the car to head for work around 6:30 am, most of the time the range is the same, sometimes it is a mile or two lower, and sometimes it is a few miles higher. Status is still charging complete. I have not tried to correlate the differences to temperature (i.e., if the battery is cold and regen is limited) but that might be something to consider.

Uncle Paul | December 28, 2018

These gauges are not that precise. Difference between 75-76% could just be a rounding error, or even due to your battery getting a little warmer.

Even my expensive watch can gain a minute or so a month : >)

Redmiata98 | December 29, 2018

Had the same problem after loading 48.12.1 update, but it self corrected after the 3rd charge and has not reoccurred.

dpm526 | January 1, 2019

overcharing hasn’t happened for several nights in a row now so things seemed to have worked themselves out.

Charge port door started working again too. The fix seemed to be connected to the latest update.

Thanks all for the input and ideas!

dpm526 | January 1, 2019

overcharing hasn’t happened for several nights in a row now so things seemed to have worked themselves out.

Charge port door started working again too. The fix seemed to be connected to the latest update.

Thanks all for the input and ideas!