Wiki Sudden Loss Of Range With 2019.16.x Software

[Droschke]

But, I think he would be open to learning more and advocate for us with a direct channel to engineers.

Then he deserves more than 1 beer. Buy him 2.

 

[dark cloud]

I had lifetime 297Wh/mi and recently it went to 298. I'm sure there are others that are much lower which I don't know how they do it other than drive really, really slow and only in town.

Well maybe the pro @jerry33 can comment:

 

[Droschke]

A few months back a few of us made a post about not being able to make the Rated range by driving the Wh/mile. The whole issue is not that your not getting the correct mileage it's the issue that the Rated range is based on using 100 percent of usable pack. When in reality you are only able to use total pack minus 4kWh and the SoC UI scales to this so you never see it.

The 100% of the "usable" pack already excludes more than 4kWh. All analyzed here.

 

[jerry33]

Well maybe the pro @jerry33 can comment:

View attachment 426641

About 50% of the miles are road trip miles. The trick is to know when to slow down and when to speed up. It also helps if you have a commute that is asymmetrical so you don't lose what you gained going the other way. The commute also needs to be long enough that the initial power usage is spread out (25 miles one way). Note that the Wh/mi has gone up a bit (245) since I'm out of work right now so not much driving except trips. There are also some commutes that you just can't do well on.

 

[DJRas]

A few months back a few of us made a post about not being able to make the Rated range by driving the Wh/mile. The whole issue is not that your not getting the correct mileage it's the issue that the Rated range is based on using 100 percent of usable pack. When in reality you are only able to use total pack minus 4kWh and the SoC UI scales to this so you never see it.

No, it does not use the full pack. If you look at the data below, the first column under Calculated data shows using Nominal Remaining (includes the 4kWh buffer) and the Wh/mi increases when compared to Rated range as the SoC decreases. When near full the multiplies is near 295 but at 35.9% SOC you get 325 Wh/mi. Where if you look 2 columns to the right you see the multiplier is pretty close to 276 for the entire range of SOC

 

[Droschke]

The trick is to know when to slow down and when to speed up.

Exactly. That's what I do by saying I drive "smooth", which has resulted in 285 wh/mi @43k.

 

[DJRas]

Well maybe the pro @jerry33 can comment:

View attachment 426641

Wow!!!
How do you drive down hill for over 100,000 miles???

 

[DJRas]

I asked my friend who has had ScanMyTesla for a long time to give me an old data log to see what the Wh/mi constant was prior to 2019.16.1.1 update.
His data from May 27, 2019 matches my car's 276 Wh/mi data.
Interestingly, his data from Jan 13, 2018 has 270 Wh/mi as the constant!!!

I completely expected his data to show 295 Wh/mi

If anyone can provide me more ScanMyTesla "Battery" data I can analyze it quickly and report it.
Send data to [email protected].

 

[jerry33]

Well maybe the pro @jerry33 can comment:

View attachment 426641

Today's picture.

 

[wk057]

@wk057 Have you been able to confirm your theory yet?

I have not been able to 100% confirm anything as of yet. This is definitely a pretty complex change to the SoC calculation system overall.

First, for quite some time (~5 years or so) Tesla has used their battery management system to calculate out a lot of variables about the entire system in a very granular way. A lot of these variables are deduced from various readings and are either not measured directly with sensors or otherwise impossible to measure anyway. Nevertheless, the BMS calculates this data.

One of the data bits that Tesla calculates these days, with a pretty high degree of accuracy, is the SoC and capacity of individual cell groups within the pack. This is an indirectly calculated value. They also calculate a bunch of other variables for each cell group, including estimated internal resistance, power dissipation, a couple of lifetime stress factors, and more recently a few new variables I haven't been able to figure out what they are with certainty.

However, in the handful of data logs I've gathered from affected 85 vehicles, the issue that is outward facing (loss of range) is due to one or more cell groups showing a lower max capacity than other groups. This also seems to correlate a bit with a couple of the new variables, but, again, not really sure what they are (not sure of scaling, either, so really difficult to determine what they're measuring/computing here). Only one of these vehicles did I have both before and after logs, and in that case the groups in question were on par with the other groups up until the update that caused this issue.

Long story short, this is definitely caused by the a recent software change, and is due to some new variable they're calculating. I'm not 100% sure what those variables are, however, but my gut is inclined to give them the benefit of the doubt on this one for the time being. My notes on the ongoing BMS software changes over the years have almost always been to improve some aspect of the system, unlike things like the horrible decline in the UI, for example. Either from a usability standpoint (such tweaking variables to eke out a higher charge rate, or make thermal management a little more efficient) or a safety/reliability standpoint (such as modeling and estimating the stress on cell level fusing to prevent physical damage and subsequent capacity loss).

Tesla's BMS is pretty incredible. They know their batteries, and they can infer a lot about their condition as a result. The BMS models so many different variables, most of which are not exposed to the user or even on CAN in any way without some prodding and/or modification. To my knowledge, there isn't a better BMS setup out there.

This particular situation doesn't seem to be a screw up... if it's reducing the max charge, it's doing it for a reason. I do think Tesla should make that reason known, however, to affected owners. My suspicion is that doing so would open them up to large warranty replacement costs, though... and I'm not really sure where that would sit legally overall. If the reduction is due to some kind of variable that's a result of regular lithium ion degradation from normal use, then, while crappy for the owner, it may be for the best. If it's due to some now-detectable defect, however, I'd say Tesla should be liable to correct the issue with a replacement pack.

This is some speculation, but in either case, I'm inclined to believe that there is a potential safety issue involved here... and Tesla's silence on the situation with lack of a clear response to affected owners leads me to believe that the issue lies in the now-detectable defect category. Again, speculation... but it fits.

All of that said, I went and reset the NVRAM of my one customer's BMS who was affected by this, as an experiment of sorts (at their request after discussing the situation in detail). Basically, the BMS will recalibrate and recalculate all of its internal variables over the next couple of weeks. I modified the software to expose pretty much everything possible for logging, and I'm hoping I'll be able to better monitor it and get a better idea what's going on over the next few weeks, assuming the issue resurfaces.

 

[faughtz]

I have not been able to 100% confirm anything as of yet. This is definitely a pretty complex change to the SoC calculation system overall.

First, for quite some time (~5 years or so) Tesla has used their battery management system to calculate out a lot of variables about the entire system in a very granular way. A lot of these variables are deduced from various readings and are either not measured directly with sensors or otherwise impossible to measure anyway. Nevertheless, the BMS calculates this data.

One of the data bits that Tesla calculates these days, with a pretty high degree of accuracy, is the SoC and capacity of individual cell groups within the pack. This is an indirectly calculated value. They also calculate a bunch of other variables for each cell group, including estimated internal resistance, power dissipation, a couple of lifetime stress factors, and more recently a few new variables I haven't been able to figure out what they are with certainty.

However, in the handful of data logs I've gathered from affected 85 vehicles, the issue that is outward facing (loss of range) is due to one or more cell groups showing a lower max capacity than other groups. This also seems to correlate a bit with a couple of the new variables, but, again, not really sure what they are (not sure of scaling, either, so really difficult to determine what they're measuring/computing here). Only one of these vehicles did I have both before and after logs, and in that case the groups in question were on par with the other groups up until the update that caused this issue.

Long story short, this is definitely caused by the a recent software change, and is due to some new variable they're calculating. I'm not 100% sure what those variables are, however, but my gut is inclined to give them the benefit of the doubt on this one for the time being. My notes on the ongoing BMS software changes over the years have almost always been to improve some aspect of the system, unlike things like the horrible decline in the UI, for example. Either from a usability standpoint (such tweaking variables to eke out a higher charge rate, or make thermal management a little more efficient) or a safety/reliability standpoint (such as modeling and estimating the stress on cell level fusing to prevent physical damage and subsequent capacity loss).

Tesla's BMS is pretty incredible. They know their batteries, and they can infer a lot about their condition as a result. The BMS models so many different variables, most of which are not exposed to the user or even on CAN in any way without some prodding and/or modification. To my knowledge, there isn't a better BMS setup out there.

This particular situation doesn't seem to be a screw up... if it's reducing the max charge, it's doing it for a reason. I do think Tesla should make that reason known, however, to affected owners. My suspicion is that doing so would open them up to large warranty replacement costs, though... and I'm not really sure where that would sit legally overall. If the reduction is due to some kind of variable that's a result of regular lithium ion degradation from normal use, then, while crappy for the owner, it may be for the best. If it's due to some now-detectable defect, however, I'd say Tesla should be liable to correct the issue with a replacement pack.

This is some speculation, but in either case, I'm inclined to believe that there is a potential safety issue involved here... and Tesla's silence on the situation with lack of a clear response to affected owners leads me to believe that the issue lies in the now-detectable defect category. Again, speculation... but it fits.

All of that said, I went and reset the NVRAM of my one customer's BMS who was affected by this, as an experiment of sorts (at their request after discussing the situation in detail). Basically, the BMS will recalibrate and recalculate all of its internal variables over the next couple of weeks. I modified the software to expose pretty much everything possible for logging, and I'm hoping I'll be able to better monitor it and get a better idea what's going on over the next few weeks, assuming the issue resurfaces.

Thanks @wk057, I am very interested in what you learn along the way, so that my actions are informed with your data.

 

[Matias]

I asked my friend who has had ScanMyTesla for a long time to give me an old data log to see what the Wh/mi constant was prior to 2019.16.1.1 update.
His data from May 27, 2019 matches my car's 276 Wh/mi data.
Interestingly, his data from Jan 13, 2018 has 270 Wh/mi as the constant!!!

I completely expected his data to show 295 Wh/mi

If anyone can provide me more ScanMyTesla "Battery" data I can analyze it quickly and report it.
Send data to [email protected].

How “ScanMyTesla” determines this value and what does it actually mean?
Isn’t “rated” in U.S.A. rated by EPA? I mean, Tesla can’t change it at will?

 

[AmpedRealtor]

What do you think is the biggest risk for them: the battery issue, quality issues (like soft Model 3 paint?) or FSD commitments?

Soft paint is a myth, don't get sucked into that hole dug by detailers and aftermarket exploiters. I think the biggest risk to Tesla is Elon Musk himself. Instead of focusing on getting certain things right, such as quality manufacturing, delivery, and hence profitability, he continues to increase Tesla's level of distraction and money spend on unnecessary things like solar cells, power walls, semi truck, autonomous taxi fleet, vehicle insurance, Model Y, new Roadster, etc. By blitzing the media and keeping everyone's head spinning with new announcements and directions, he gives everyone something else to look at. He should be focusing on only one thing: maximizing Model 3 manufacturing, delivery, and profitability. Everything else is secondary. If Tesla can't get the vehicle part right, nothing else matters.

Do you mean altruists with money?
Maybe they feel that keeping Tesla alive is ultimately in their best interest?

More like stock twits.

Since we're rounding back to conjecture that Tesla is intentionally choosing massive lawsuits because it can't afford the warranty service these batteries require, let me say once again in the hopes someone at Tesla reads these forums:

TESLA, LET US PAY TO UPGRADE OUR BATTERY. YOU DID IT YEARS AGO AND THIS WAY YOU CAN TURN BAD PUBLICITY AND POOR POLICY INTO GOOD PUBLICITY AND PROFIT!

Since this is all naive optimism, I'll add some more: If they were updating the S/X platform to Model 3's 2170 batteries, they would want to perform a large scale warranty service like this using those newer cells because it's much cheaper - a Model 3 LR pack has almost the same capacity as an 1865 S85 pack, but only 5500 cells instead of 7400 cells, so there are fewer raw materials and less labor. If I had to replace a bunch of batteries, I'd want to use the cheaper ones.

You do realize that this is not a viable solution, right? Asking owners who have been wronged to spend more money is not a solution, it's an insult. Money may come out of faucets for some here, but not for me. You are encouraging Tesla to continue their bad behavior by telling them you want to reward them for it.

I think that would get more attention- I saw nothing where I gave up any future rights, and it takes less than 10 minutes, and they promise a swift response.

If someone wins, can that be used as a precedent for future arbitrations? Can Tesla's nationwide policies be changed with something like this?

A few months back a few of us made a post about not being able to make the Rated range by driving the Wh/mile. The whole issue is not that your not getting the correct mileage it's the issue that the Rated range is based on using 100 percent of usable pack. When in reality you are only able to use total pack minus 4kWh and the SoC UI scales to this so you never see it.

EPA rating is achieved by driving the vehicle until it shuts down. Rated range multiplier is supposedly calculated based on the results of this test. Driving until the car dies (per EPA) tests usable capacity.

All of that said, I went and reset the NVRAM of my one customer's BMS who was affected by this, as an experiment of sorts (at their request after discussing the situation in detail). Basically, the BMS will recalibrate and recalculate all of its internal variables over the next couple of weeks. I modified the software to expose pretty much everything possible for logging, and I'm hoping I'll be able to better monitor it and get a better idea what's going on over the next few weeks, assuming the issue resurfaces.

Four years ago, after asking why a loaner of the same vintage as my car showed higher range, Tesla service said that they "reset the battery" on some of their vehicle loaners in order to re-calculate the range. I asked them to do that to my vehicle and they refused, later recanting and telling me no such reset function exists. Now you have confirmed that it does, indeed, exist and Tesla was right the first time. They let a cat out of the bag and then tried to take it back!

Tesla service is apparently able to do this somehow. Is there a way I can do this?

 

[NickleNiceness]

I think by "reset" they meant "balance" by letting SOC go very close to zero and charging to 100%. There are a billion threads on this

 

[MaryAnning3]

my gut is inclined to give them the benefit of the doubt on this one for the time being.

Thanks wk057. Great post and interesting analysis. much appreciated.

 

[Droschke]

If the reduction is due to some kind of variable that's a result of regular lithium ion degradation from normal use, then, while crappy for the owner, it may be for the best.

As you know, the range loss was sudden, some by over 30 miles. Like you have hypothesized, if this range loss is due to the regular lithium ion degradation from normal usage should we then assume the BMS reporting of that regular lithium ion degradation was incorrect pre-update since the range loss has been sudden? If so, why then for just small percentage of the cars (On Edit: it's the same BMS and it should have been reporting it incorrectly for all cars)?

Thanks for your insight.

 

[faughtz]

Should more of us file too?

After submitting the claim yesterday, I received the above, this morning.

Encourage everyone to at least take a look, and appreciate feedback and thoughts from anyone that has been through the NCDS process.

 

[Droschke]

View attachment 426716


After submitting the claim yesterday, I received the above, this morning.

Encourage everyone to at least take a look, and appreciate feedback and thoughts from anyone that has been through the NCDS process.

A very helpful and detail thread on the process here started by a member who has just gone through it, although for a different issue.

 

[faughtz]

A very helpful and detail thread on the process here started by a member who has just gone through it, although for a different issue.

Thanks much, had not seen this...

 

[DJRas]

How “ScanMyTesla” determines this value and what does it actually mean?
Isn’t “rated” in U.S.A. rated by EPA? I mean, Tesla can’t change it at will?

EPA rating was determined prior to sale with a new full pack.
I BELIEVE Tesla is not obligated to maintain that Wh/mile rating as the vehicle ages, battery degradation occurs, or they learn more about the vehicle.

If, however, they modify this value to avoid warranty claims it would be a different situation- though not EPA related.