Can’t Charge Above 97%?

[FlyingCookie]

Hi guys,

In preparation for Holiday traveling, I set My charge limit to 99% last night. When I woke up this morning at 7am, i found that the car was still charging at 1kw at 97%. This was from an 85% SOC and charging scheduled to start at 3AM. The car sent me the notification that charging had completed at 7:20ish, with SOC still at 97%

It got kind of cold (29f) last night, so I’m wondering if this is normal when charging a cold battery. I called Tesla and they didn’t find anything unusual in the logs, but even when I set the charge limit to 100% it only charged for another 5 minutes or so and then stayed at 97%.

Prior to this, my 100% was 263 miles, so only about 2 miles of degradation. I very rarely (less than once per 6,000 miles or once per month) charge to 100%

Also, my current charging while visiting family for thanksgiving, just for laughs. (Car will just sit here for the next ~32 hours, and I’m well within range of the Atlanta Supercharger)

 

[rhyd]

It seems common for the last couple of percent to take a very long time. Some call this 'balancing' not sure if that is correct (there are some claims that balancing happens regularly during 'daily' SoC) but certainly it seems very common for the charge rate to taper off to almost nothing at the highest SoC (Bjorn has a video showing this). It seems reasonable for the car to tell you to set off and hit the road at 97% rather than wait another 2 hours for it to cram in every last electron. If you are really worried about it then I'd give the car a couple of hours charging after 97% to reach 100%. Whether there is balancing or not it will almost certainly be recalibrating the 100% counter, so you should then get the reported SoC and range you're after

 

[FlyingCookie]

Update:

After the roughly 40 hours it took to get to 98%, the car stopped charging there. Ambient temperature was about 50F, so I don't think battery temperature would have had anything to do with it this time. It wasn't balancing the battery, as the UMC was not showing any power flow, just a solid green light. This is similar to what the EVSE at my apartments did with the early stop at 97%, as I heard the relay open just before I approached the car, where I then heard the relay closing again.

Previously when the car has balanced, it's gotten to 99% and then sat there for about an hour, but still pulling about 2 amps from the wall at 240V. That was not the case either of these times.

I called Tesla about it, and the guy on the phone didn't know what to blame it on. Said he didn't see anything in the logs, though I don't know how much he could actually access and look at. I may call my local service center about it and have them give their opinion. I just want to make sure I haven't had some kind of battery damage occur. If it's just not charging to 100% due to it being so cold (I know most people's cars won't show their full rated range when cold), that's perfectly fine... But i've charged to 100% in similar weather in the past, and it didn't stop early.

 

[SteelSully]

Update:

After the roughly 40 hours it took to get to 98%, the car stopped charging there. Ambient temperature was about 50F, so I don't think battery temperature would have had anything to do with it this time. It wasn't balancing the battery, as the UMC was not showing any power flow, just a solid green light. This is similar to what the EVSE at my apartments did with the early stop at 97%, as I heard the relay open just before I approached the car, where I then heard the relay closing again.

Previously when the car has balanced, it's gotten to 99% and then sat there for about an hour, but still pulling about 2 amps from the wall at 240V. That was not the case either of these times.

I called Tesla about it, and the guy on the phone didn't know what to blame it on. Said he didn't see anything in the logs, though I don't know how much he could actually access and look at. I may call my local service center about it and have them give their opinion. I just want to make sure I haven't had some kind of battery damage occur. If it's just not charging to 100% due to it being so cold (I know most people's cars won't show their full rated range when cold), that's perfectly fine... But i've charged to 100% in similar weather in the past, and it didn't stop early.

Hi FlyingCookie,

I'm curious if you ever took your car in to get this checked out? I stopped by a local SC today and arrived with a very low SOC (about 1%). I decided to charge to 100% to rebalance (which I haven't done before), but once I got to 96% it was only charging at the rate of 1KWh and eventually completed at 97%. I even unplugged for a few minutes and plugged back in and it once again finished in about 2 add'l minutes at 97%.

I have a RWD 75 (June 2016) and my final range at 97% was only 221. Less than 5 months ago when I did the software update from a 70 to 75, I was getting 239-240 of range. Maybe this is within the normal range of loss after 1.5 years (35k miles), but it sure seems high when the RWD 75 new should have about 249 miles of range...

 

[ucmndd]

I have a RWD 75 (June 2016) and my final range at 97% was only 221. Less than 5 months ago when I did the software update from a 70 to 75, I was getting 239-240 of range. Maybe this is within the normal range of loss after 1.5 years (35k miles), but it sure seems high when the RWD 75 new should have about 249 miles of range...

No real answers for you but I had the same experience on a trip last weekend with my Dec '16 S75, stopped charging at 97% and wouldn't go higher. A couple charges later on the way home I charged all the way again and it reached a full reported 100%. /shrug

I'm also a little over 35k miles and have about the same 100% range as you - 229. Rather disappointed with the observed degradation of the 75kwh pack. Hope it slows down soon.

 

[OlavA]

I have a 75 and get 230 miles at 100%. I have 33K miles on a Oct 16 car.
I commute 600 miles a week.

Just wanted to add my data point.

 

[FlyingCookie]

I ended up trying to charge to 100% a few days later, and saw the car charge all the way and hit my usual rated range of 263 miles. I've noticed that on cold days (below 40F) I can usually plan on the car stopping early at 97-98%. I'm assuming this is just the car trying to protect the battery and not overcharge it when cold, but I can't be entirely sure. I've had Tesla look at it, and had the logs pulled, and no one can see anything unusual.

For now, I'm not too worried about it. Car is driving fine, and I've cycled the battery probably 20 times since then and have seen no further degradation, so unless it gets worse, I likely won't pursue a solution any further.

 

[trond.strom]

I have the same issue in my 2015 85D. The car doesnt charge to 100%. Another odd thing is that if I set it to charge to 70% it regularly says charging complete at 68%.

 

[Xtek]

Just had this happen on my X100D. I almost never charge to 100%. I think I've done it 5~ times or so in 5 months of ownership to keep the pack balanced. I decided late last night I was going to start it as it would finish round 5 AM when I needed to go to the store and I noticed it stopped @ 97%/285 rated miles. Normally a 100% charge is 295/296 rated miles. My last true 100% charge was in late December and I actually hit 296 rated miles. So less than 2 months later it seems odd that it would lose 10 miles of range.

Going to drive it around a bit for a few days and se eif I can get back to 100%.

 

[Buster1]

I wonder if this is the BMS algorithm simply doing its best?

Recall that when your battery is “kept in the middle” charge level, the BMS is guessing at actual charge level until it can hit a hard calibration point (0% or 100%).

 

[Xtek]

I wonder if this is the BMS algorithm simply doing its best?

Recall that when your battery is “kept in the middle” charge level, the BMS is guessing at actual charge level until it can hit a hard calibration point (0% or 100%).

That's what I'm assuming. I commute 40 miles round trip for work and only charge to 70% 95% of the time and return home at 50%.

 

[Snerruc]

That's what I'm assuming. I commute 40 miles round trip for work and only charge to 70% 95% of the time and return home at 50%.

Don’t know if anyone else has noticed this, but my S75 sometimes will go 2-4 miles before the range will drop on the dash. At other times when I start driving after charging, range will drop or raise immediately after I start driving.

 

[Buster1]

Don’t know if anyone else has noticed this, but my S75 sometimes will go 2-4 miles before the range will drop on the dash. At other times when I start driving after charging, range will drop or raise immediately after I start driving.

Yep, normal.

Think about it this way. The range/percentage on the dash is called Total Estimated Driving Distance (TEDD) per the owner’s manual. It’s simply the BMS estimation of how far you’re gonna go. If you are driving slow and efficiently, it will update and estimate farther distances. If you’re on the track and doing Ludicrous launches, it might reflect differently and show you with a really different number. It’s simply the BMS algorithm attempting to estimate how far until “empty.”

(PS- if you watch some YouTube vids on folks who run their Tesla’s to 0... you’ll note some people go many miles past 0 before the car dies, and some cars die at 1-2% remaining or 3 or 5 miles remaining, etc. BMS algorithm ain’t perfect.)

 

[Xenoilphobe]

Double check the battery charge percentage slider and make sure you moved it to 100%, sometimes its a hair off..

 

[Xtek]

Mine was for sure at 100%.

 

[Larsen]

I see the same situation, with the last attempt to charge up to 100%, I received a "charging complete" notice of 95%. Before this attempt, I charged the car unsystematically (70-80-90% SOC) and very rarely discharged below 30%.
But that's what I noticed when reading messages where people notice such a circumstance - a large number of these messages are dated by autumn and winter dates when it's cool. Perhaps this fault is low temperature?
I received 95% on January 24, 2018, when we had a temperature of -9C (16F)

 

[Xtek]

My X sits in a garage where it rarely goes below 55F. Will give it a shot again soon and report back.

 

[Xtek]

Car spent almost a week at the service center. Tried to charge to 100% before going on a trip and it got to 96%/282 miles, got worse.

 

[d21mike]

I had the same issue with my S75D. Normally I charge to 80% but wanted to try for a 100% charge and first time was 97% and then 99%. These are at my home on NEMA 14-50. So then decided to try at a Supercharger and it went to full 100% before stopping. Have not tried again at home.

 

[Xtek]

I had the same issue with my S75D. Normally I charge to 80% but wanted to try for a 100% charge and first time was 97% and then 99%. These are at my home on NEMA 14-50. So then decided to try at a Supercharger and it went to full 100% before stopping. Have not tried again at home.

That might line up with other reports i've seen. Sounds like it's actually an issue with the charger calibration and since a supercharger uses DC and bypasses the charger that would explain it.