Battery degradation, real or imagined?

Dr. J

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#21
When I got the RWD, a full charge calculated out at 310. The RWD showed no change until the update that officially changed the RWD rating from 310 to 325. That change I fully understand. Remember that the RWD was originally rated at 310 and that was later changed to 325.

The AWD is still rated at 310. When I got mine (30 Sept) it calculated out to 308. After a few weeks, before I even got the RWD, it was at 295 and has stayed there. There is a Like Tesla video on this issue. According to Tesla, it comes from charging to only 70%. Tesla says charge to 90% to prevent it. Then they say to reset the BMS, discharge to under 15 % and charge to 100%. I have done that twice but it hasn't reset.
Yes, I understand that as well. ;) I just don't believe it. First, there is no degradation that results from charging to 70%. There is also probably no degradation from charging to 90% on a daily basis, but degradation becomes likely by charging to 100% then completely cycling the battery to a low SOC, lathering, rinsing and repeating. So the issue being addressed is merely calibration, and the supposed "cure" for miscalibration is the thing that causes degradation (cycling the battery to high charge and deep discharge). I understand that it's the orthodox thinking, but I don't think it's a good idea to do it. And I especially don't think it's good for the battery to do it repeatedly.

There's a lot of information we don't have about the 2170 cells used in the Model 3. I'm a little curious what the BMS may report about my car's range, but nearly all the time I keep it on %, not distance. That way I don't think it about much, which I believe is the best way to care for the battery. Just my opinion, no facts to back it up.
 

SR22pilot

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#22
Yes, I understand that as well. ;) I just don't believe it. First, there is no degradation that results from charging to 70%. There is also probably no degradation from charging to 90% on a daily basis, but degradation becomes likely by charging to 100% then completely cycling the battery to a low SOC, lathering, rinsing and repeating. So the issue being addressed is merely calibration, and the supposed "cure" for miscalibration is the thing that causes degradation (cycling the battery to high charge and deep discharge). I understand that it's the orthodox thinking, but I don't think it's a good idea to do it. And I especially don't think it's good for the battery to do it repeatedly.

There's a lot of information we don't have about the 2170 cells used in the Model 3. I'm a little curious what the BMS may report about my car's range, but nearly all the time I keep it on %, not distance. That way I don't think it about much, which I believe is the best way to care for the battery. Just my opinion, no facts to back it up.
I just want the BMS to recalibrate. The two cycles I did aren't enough to hurt the car and I have no intention of constantly doing the deep discharge/100% charge routine. I did it twice in a row based on direction from Tesla. I haven't rushed to put the car into service because it isn't that big of a deal but it is something many people are seeing. Since people want to follow real degradation in the battery they first need to get the BMS accurately calibrated.
 
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Frully

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#23
I just want the BMS to recalibrate. The two cycles I did aren't enough to hurt the car and I have no intention of constantly doing the deep discharge/100% charge routine. I did it twice in a row based on direction from Tesla. I haven't rushed to put the car into service because it isn't that big of a deal but it is something many people are seeing. Since people want to follow real degradation in the battery they first need to get the BMS accurately calibrated.
Absolutely. If you're still seeing the crud numbers after only 6 months and after 2 battery cycles it stands to reason something needs to be checked. I've had luck with the level 2 techs on roadside assistance remoting into the car to get some diagnostics back when I had the black screen issue -- might help just to chat with them before service appointment so they can see (since they can read the bms info remotely) if anything is wrong.
 

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#24
Absolutely. If you're still seeing the crud numbers after only 6 months and after 2 battery cycles it stands to reason something needs to be checked. I've had luck with the level 2 techs on roadside assistance remoting into the car to get some diagnostics back when I had the black screen issue -- might help just to chat with them before service appointment so they can see (since they can read the bms info remotely) if anything is wrong.
Good advice. I should have mention that I got the recalibration advice from Tesla after they said they looked at my car and didn't see any battery issues.
 

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#25
Good advice. I should have mention that I got the recalibration advice from Tesla after they said they looked at my car and didn't see any battery issues.
Entire guess: Strikes me that a level1 tech probably has a much-simplified screen showing car subsystems as green-light, yellow-light, red-light etc where one of the more-nerdy folks could better interpret individual voltage discrepancies.
 

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#26
When I got the RWD, a full charge calculated out at 310. The RWD showed no change until the update that officially changed the RWD rating from 310 to 325. That change I fully understand. Remember that the RWD was originally rated at 310 and that was later changed to 325.

The AWD is still rated at 310. When I got mine (30 Sept) it calculated out to 308. After a few weeks, before I even got the RWD, it was at 295 and has stayed there. There is a Like Tesla video on this issue. According to Tesla, it comes from charging to only 70%. Tesla says charge to 90% to prevent it. Then they say to reset the BMS, discharge to under 15 % and charge to 100%. I have done that twice but it hasn't reset.
Right AWD didn’t change as far as I know.

Just as another datapoint. When I first got my AWD (P) I supercharged it to 100% within the first week or so. Got 310 on the button. Then I did it 3 months later. Got 309. Just did it today (first time on home charger). Got 307. That is 7500 miles and 8 months. I think those sort of differences are practically in the noise.

I try to vary my charging. Very often 90% then run it down to around 40% and charge on the weekend. I stopped “happy Tesla, plugged in Tesla” when Tesla introduce the random “topping off” every one hour in the middle of the night.
 

JML

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#27
I've posted in several threads on this issue that my AWD took a dramatic drop from about 308 to 268 as the 100% charge. This drop was near or at the upgrade to 2019.8.5, and has stayed low, or gotten worse, through 2019.12.1.2 and 2019.16.2. My drop also occurred at a time the car was in service for two weeks. Contacts with email support have told me to charge to 100%, and contact service. Charging to 100% did nothing to return indicated range.

I have an appointment to take the car in to check it out on next Monday. Just now, a week before the appointment, I got an email from the Virtual Diagnostics Team saying:
I’m with the Virtual Diagnostics team here at Tesla Service off East Evans, and I am reviewing your upcoming appointment for 6/17, and wanted to reach out proactively.

There was a recent Firmware bug that effected the displayed range on Model 3s, however it does not affect the actual miles left. It can take roughly 2-3 weeks for the vehicle to re-calculate actual mileage. We recommend charging to 90% during this time.

Since this was a result of a Firmware bug, there is no need for a service visit at this time.
So, straight from Tesla, there is a bug. Clearly it only affects some people. I'm assuming the direction to charge to 90% is so that way I get enough range, not as a method to fix the bug.

I replied
Thank your for getting in touch with me. My range drop happened very suddenly at the beginning of April, so I've been showing the reduced range for about 10 weeks.

Can you let me know if this indicates some problem other than the firmware bug? I've not seen any re-calculation of actual mileage in that time, and if anything I see a downward trend in the displayed range.
I'll follow up here if I get anything back from them.
 

JML

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#28
Heard back from Tesla service right away:
Have you been consistently charging to 90%? Doing so will help the recalculation process.
I will give that a try.

My car is out of commission at the moment, but hopefully will be fixed this week, and then I'll charge to 90% for a few weeks. I usually charge to 70-80% at home (depending on which posts I've most recently read by somebody who is absolutely sure that whatever state of charge is the best and any other will kill your car).
 

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#29
Heard back from Tesla service right away:

I will give that a try.

My car is out of commission at the moment, but hopefully will be fixed this week, and then I'll charge to 90% for a few weeks. I usually charge to 70-80% at home (depending on which posts I've most recently read by somebody who is absolutely sure that whatever state of charge is the best and any other will kill your car).
Have you supercharged at all?
I have zero evidence for this but my gut feeling is a good high kw charge is heathy for battery too. Occasional SuperCharge is part of my “vary it up” recipe. Again, with zero proof of this.

Too much of anything is not good. Too much SC, to little SC, recharging over a narrow range, to wide a range, to low or to high.

BTW what is your car out of commission for?

268 does seem way out of whack for 100%

So many issues that have “simple solutions” sometimes mask real problems and get tossed into the simple solution pile.

You are aware that the was a TSB on batteries from last summer. I forget exact dates. Missing fusable links that could case cells to prematurely remove themselves from the pack.

I doubt this is a recent release software bug. Otherwise I think we’d see a lot more folks complaining. But anything is possible.
 

JML

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#30
Have you supercharged at all?
I have zero evidence for this but my gut feeling is a good high kw charge is heathy for battery too. Occasional SuperCharge is part of my “vary it up” recipe. Again, with zero proof of this.

Too much of anything is not good. Too much SC, to little SC, recharging over a narrow range, to wide a range, to low or to high.

BTW what is your car out of commission for?

268 does seem way out of whack for 100%

So many issues that have “simple solutions” sometimes mask real problems and get tossed into the simple solution pile.

You are aware that the was a TSB on batteries from last summer. I forget exact dates. Missing fusable links that could case cells to prematurely remove themselves from the pack.

I doubt this is a recent release software bug. Otherwise I think we’d see a lot more folks complaining. But anything is possible.
I've never supercharged. I almost always only charge at 22mph. Sometimes that is 24 amps by 238 volts at home, and sometimes it is 30 amps by 198 volts at work.

If you follow the link, you'll see my rear window had an encounter with a not-completely-raised garage door.

I've asked multiple times about that TSB, but I've never had any response. Complete silence. I'd be happy with a "we checked, but your VIN isn't on the list."

The final response I received is below. It goes off on the "a full tank of gas tangent," but the instruction it does give is to drop below 40%, let it sit for a few hours, charge to 90%, and then let it sit for a few hours. I'd not seen the "resting" statement before. It isn't temperature related, but rather that the BMS takes some time before it takes measurements.

Frankly, I'm not sure I really believe any of this. Tesla service employees, who should know better, are on record as saying wrong things like the indicated range takes into account driving style. I would not be surprised at all if service centers are operating under a directive to get as many appointments cancelled as they possibly can.

And, of course, it links to that one article again. That is a great article if you own a 5 year old Model S. I've not seen anything that demonstrates the results apply to different cells in a different package.
"The diagnostic tools we have available for looking at battery health and possible degradation are designed to perform a thorough check of the High Voltage battery for any issues that may affect and decrease range and/or capacity, there are multiple sensor’s information used to determine if an issue is present. Another test that we use, is to compare the calculated capacity of your vehicle against the rest of the entire fleet of Model 3 cars with the same type of battery installed. No issues were noted during either of these tests and your vehicle is very close to the rest of the Model 3’s out there with the same battery and similar mileage.

I do want to emphasize that the displayed range on the screen is a calculation, not a definitive measurement of capacity. Unfortunately, there is no way to directly measure this value like a fuel level float and the size of the gas tank in a gas powered vehicle. The range display can change over time due to numerous values taken into consideration, such as driving habits, temperature of the battery, charging habits, etc., but this doesn’t reflect the actual capacity of the battery. This is why we recommend utilizing the percentage display instead of the mileage view for remaining range. My gas powered vehicle never gets exactly what the estimated remaining mileage shows, but the fuel gauge (0% as empty and 100% as full) provides an accurate time of letting me know when to stop and refuel. Each time I refuel and reset the trip odometer to calculate fuel mileage, the distance I can travel varies depending on how I was driving the vehicle (lots of uphill, high speeds, windy days, etc.). Rarely do I get the exact same mileage to empty when I am done refueling.

One thing that will help maintain the most accurate calculation possible is to occasionally drive the vehicle to a state of charge below 40% or so and allow it to sit overnight or use scheduled charging to allow the vehicle to rest for a few hours. Then charge the vehicle fully, 90% or above state of charge, and let the vehicle sit again for a few hours. Our engineers have told me that the sensor values in the battery may not be reliable unless the vehicle sits for a few hours, so that is when the system is programmed to take readings and incorporate those into the calculations. Also, the system can only make small step changes at a time. It might take time to see an adjustment or change in the displayed range.

However, it is not abnormal to see slightly lower range to when the vehicle was brand new. Indeed, li-ion batteries do have a first expected small loss of retention during the first months of cycling (think of how long your phone now holds a charger vs when new). Our battery cell retention then levels off for years to come. I would check out, for instance, customer pulling data on our Tesla fleet retention, https://electrek.co/2016/11/01/tesla-battery-degradation/ , this is a very interesting read from independent testing, we had no input on this. It is overall pretty impressive. You will see that a few percent decline over the first few thousand miles is not abnormal or cause for concern. "
 

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#31
I've never had it lower than about 180 miles. I'm going to run it low this weekend. I'll report back what my new 100% charge level is. Thanks for your guidance.
@JML, thanks so much for the plethora of information you shared. It's very helpful to read what you've learned, and what Tesla does around this problem.

I drove the car down to 25 miles, and immediately supercharged it back to 100%. No change to my range. It's still 282 miles. I suppose it's time to involve Tesla service. I will charge using the "let it sit" process described above to see if that yields any change. It's also worth mentioning the major leap in my firmware version didn't change a thing.

As an aside, I've attempted to charge to 100% twice via supercharger since getting the car. Each time, it never completed. As the charge neared completion it would just sit with the message "Calculating", so I stopped. I scoured forums about this problem and found it's very common, almost typical. I'll stick with 95% charge (or less) at superchargers going forward, even on trips.
 
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MelindaV

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#32
I've never supercharged. I almost always only charge at 22mph. Sometimes that is 24 amps by 238 volts at home, and sometimes it is 30 amps by 198 volts at work.

If you follow the link, you'll see my rear window had an encounter with a not-completely-raised garage door.

I've asked multiple times about that TSB, but I've never had any response. Complete silence. I'd be happy with a "we checked, but your VIN isn't on the list."

The final response I received is below. It goes off on the "a full tank of gas tangent," but the instruction it does give is to drop below 40%, let it sit for a few hours, charge to 90%, and then let it sit for a few hours. I'd not seen the "resting" statement before. It isn't temperature related, but rather that the BMS takes some time before it takes measurements.

Frankly, I'm not sure I really believe any of this. Tesla service employees, who should know better, are on record as saying wrong things like the indicated range takes into account driving style. I would not be surprised at all if service centers are operating under a directive to get as many appointments cancelled as they possibly can.

And, of course, it links to that one article again. That is a great article if you own a 5 year old Model S. I've not seen anything that demonstrates the results apply to different cells in a different package.
I'd say your range drop is more than "slightly lower than when new" and more than "a few percentage". Your current 268 miles is essentially down 14% from 310 miles. It'd just be nice if they specifically came out and said there is a software fix for this.
I've already cycled mine below 40% and back up to 90% multiple times, and each time seems another mile or two is dropped off the estimated range, so not convinced it is something the car can fix on its own.
 

N54tt

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#33
Heard back from Tesla service right away:

I will give that a try.

My car is out of commission at the moment, but hopefully will be fixed this week, and then I'll charge to 90% for a few weeks. I usually charge to 70-80% at home (depending on which posts I've most recently read by somebody who is absolutely sure that whatever state of charge is the best and any other will kill your car).
Thanks for all the info on your experience. Have they mentioned if the update to fix the “bug” is even out yet? And if so what version?
 
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#34
Following along. I’ve tried 4 times (before heading out on road trips) to charge my AWD to 100%, but have never hit 310. 304 initially, 300 last. My daily commute is 150 miles. I charge to 90% daily, and repeat with scheduled charging starting at 8PM. Charge finishes around 2/3AM and I’m back on the road at 4:15AM. What’s odd, is my starting range at 90% is now down to 266mi today (vs 279). Compounding my concern is the the efficiency vs use. Rated efficiency is 240w/mi, right? So assuming my commute was exactly 240w/mi, the 150 mile commute should put remaining range at 116mi (266-150)? Well, even though my efficiency was 237, I’ve only got 94 miles of range left. I’m trying to figure this out but struggling.
 

MelindaV

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#35
Compounding my concern is the the efficiency vs use. Rated efficiency is 240w/mi, right? So assuming my commute was exactly 240w/mi, the 150 mile commute should put remaining range at 116mi (266-150)? Well, even though my efficiency was 237, I’ve only got 94 miles of range left. I’m trying to figure this out but struggling.
what is being used while parked? are you using Sentry Mode or Cabin Overheat Protection? both will use a fair amount of energy while the car is sitting.
 
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#36
what is being used while parked? are you using Sentry Mode or Cabin Overheat Protection? both will use a fair amount of energy while the car is sitting.
Ah, I should known better and factored that in, however the math still doesn't add up. The garage is environmentally controlled, and maintained at 75F. I do have Sentry in use while there and I didn't factor in the drop, but at approx 1mi/hr loss, the math still doesn't add up. I know when I have tracked individual legs of the commute (without parking), my estimated remaining range is usually not what I expect when compared to the starting range factoring the efficiency statistic for that leg. I'll do a better job to track it. In all this, I understand the estimated remaining range is just that...estimated. However, if I continually drive at an efficiency rate below the rated, I would estimate I should consume less range than I have traveled.
 

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#37
what is being used while parked? are you using Sentry Mode or Cabin Overheat Protection? both will use a fair amount of energy while the car is sitting.
There was no parking according to what he said. He started at 266 miles when he left. Did 150 miles at 237 wh/mi and arrived with 94 left.

Now if it’s 94 when he leaves to go back again after parking all day that would make sense if he has Sentry and Cabin protection on.
 

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#38
There was no parking according to what he said. He started at 266 miles when he left. Did 150 miles at 237 wh/mi and arrived with 94 left.

Now if it’s 94 when he leaves to go back again after parking all day that would make sense if he has Sentry and Cabin protection on.
You're assuming it's 150 miles one way. Sounds to me like it's probably 150 miles round trip.
 

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#39
You're assuming it's 150 miles one way. Sounds to me like it's probably 150 miles round trip.
It's not clear, but you are probably right. So yeah, I agree, what's he running while parked.

It's one thing if you don't mind the battery usage for things like Cabin Cooling and Sentry, but when ever that stuff runs so does a lot other stuff (pumps, fans, etc.) and it's those I worry will not last over time running 24/7 (For some folks).

Everything is OFF for me and it has been behaving for a while now. I crack my windows, as I always have, and it stays pretty cool. I'm lucky that my work and home is pretty safe. I'll only use Sentry in unfamiliar / unsafe locations as needed (which is fairly uncommon).
 

Jason F

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#40
I charge nightly at home, up to the line on the battery display that divides DAILY and TRIP. This line appears to be the 90% charge point but it's not specific. I have LR RWD, HW3 with software 2019.16.3.

My standard charge using this setting is just over 250 miles. Have you had the same result? Extrapolating this number means my 100% charge is only about 280 miles. I suppose I should actually charge to 100% to find out what it is.

Any insight would be welcome. Is there a standard charging procedure to "reset" the battery capacity readings? I'm concerned that my battery has degraded significantly but can't see how this could be possible with such a new car.
I get about 290 at the 90% mark