2016-2017 model year 30 kWh bar losers and capacity losses

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LeftieBiker said:
SageBrush said:
LeftieBiker said:
I was afraid of this. It seems more unpredictable than with the Canary packs, though. Some 30kwh packs lose no bars for years, while others - even in milder climate - lose a bar a year. Nissan is playing games again.
I'll guess not games, but pack variability. I think AESC QC is poor. It seems fairly clear that Nissan wanted to exit AESC and go with LG cells but they are stuck for now with a 25% ownership stake in AESC and an obligation to use AESC cell ... and even less control over QC than they had before. Not that QC was ever that good to begin with.

The "games" to which I refer are claiming that this is all just a BMS programming error, and that their BMS update will fix the problem - which never really existed according to them. I was suspicious of this from the first, because a factory programming error should have affected ALL of the BMS units manufactured in a certain time frame - not just some of them.

I had the rare 2016 S with 30 kwh pack and likely did not need the programming update. I was at 100% SOH the day my car was wrecked.
 
LeftieBiker said:
Do you, or have you done computer programming of embedded systems for a living, Leftie?

You are engaging in a logical fallacy that is very similar to the "appeal to authority" that argues that only those who have been officially titled as experts in a field can understand that field, and are thus the only people to be believed in any discussion of that field. Like Ford engineers, in a discussion of why Pintos were exploding in low speed accidents. Or Boeing engineers, in a discussion of why their planes only needed one airspeed sensor, and why a system relying entirely on that sensor should be able to override pilot input...
Or a doctor in a discussion as to that funny looking spot on your face being cancer or not.

Yes, experts are wrong some of the time. Airplanes would crash less if experts were always correct. Yet you can't design a 737, now can you? (And it wasn't an "airspeed sensor", it was an angle of attack sensor, and there are two of them, not one. And that might not have been the fatal problem. )

Yes, experts are wrong some of the time.

So are you.

This isn't an "appeal to authority", it is an appeal for humility.


The "games" to which I refer are claiming that this is all just a BMS programming error, and that their BMS update will fix the problem - which never really existed according to them. I was suspicious of this from the first, because a factory programming error should have affected ALL of the BMS units manufactured in a certain time frame - not just some of them.
Problems can be complex.

Perhaps there is a BMS programming error that is only triggered if the car is charging at midnight when daylight savings time starts. Or something odd like that.

There also may be packs with physical problems. As well as BMS programming error(s).

And there certainly is climate and usage variability. As well as physical problems in some packs and BMS programming error(s).

Failure analysis isn't easy, even with the absolute best in tools and full documentation of the system.

Quoting a boss of mine, "The last bug in a system is likely to be found on the day the very last copy of the system is powered down and hauled to the junkyard."
 
WetEV said:
Yes, experts are wrong some of the time.
So are you.
Excellent post, so I'll nitpick:

Should be "Yes, experts are wrong some of the time,"
but MUCH less often than non-experts in their field.

HOWEVER, this dust-up is not experts Vs Lefty, it is Nissan Marketing Vs Lefty. Lefty has the advantage here.
 
It would certainly be interesting to know what the actual Nissan engineers were saying about this, both when the issue was discovered and when the "fix" was developed. Were they fighting it tooth and nail and warning it wouldn't work most of the time, or were they on board with it...?
 
I do make my living programming embedded systems and I've been programming in one form or another for longer than I care to admit. And in that capacity, I'm not surprised that a programming error could exhibit the symptoms reported here.

One possible scenario - and this is totally hypothetical ! - out of the millions or billions of possibilities would be something like the code had a bug that caused the system that read the battery voltage to not recalibrate itself as intended. So if the ADC that converts the battery voltage to a number for the BMS changed over time (and virtually all silicon devices change characteristics over time, temperature, use, etc) then the voltage reported to the BMS would be incorrect. Now imagine that there are multiple vendors and batches of these ADC parts. Then different cars would exhibit different behaviors over time. Fixing the software to recalibrate the part as needed would eliminate the problem and the BMS would get a more accurate reading of the actual battery voltage, as it would now be unaffected by the errors in the ADC.

In this field, much or sometimes most of the actual firmware is used to calibrate, normalize and compensate for the varying characteristics of the mechanical parts and handling errors in the various sensors. These mechanical parts include the chips that read voltages, measure current, monitor tire rotations, etc. It's not a perfect world and there are no perfect parts. Once things are converted to numbers then usually, the final results are extremely consistent but even then there can be race conditions (where 2 operations happen in parallel and the answer depends on which finishes first), rounding errors, memory corruption, etc. that can cause inconsistencies.

So while I'm a bit skeptical of any marketing department, including Nissan's, I don't think the fact that different cars exhibited different symptoms means they are lying as I would not be at all surprised to see this behavior from a programming error.
 
Now imagine that there are multiple vendors and batches of these ADC parts.

That seems reasonable as a hypothesis, but I see a couple of problems with it. First, I don't think that Nissan uses multiple vendors for the BMS, based on their use of a single manufacturing plant for many years to provide them with their North American packs. If they had done so, though, why would the problem only appear in 2016, and if they first used multiple vendors then, why aren't they recalling just the packs using the marginal BMS units for the software fix? They should know which ones they are based on the VIN. The best theory here, IMO, is that there are both defective BMS units AND defective packs, and that Nissan has chosen to address only the former in order to save money. They probably figured that the bad packs would develop bad cells and be replaced for that reason, but it seems that some of them may instead degrade quickly. There is also the very real possibility that the 30kwh pack is susceptible to heat in much the same way as the original 'Canary' pack, and the BMS problem has contaminated the data enough for it to not yet be obvious.

All that we really know so far is that the BMS update doesn't fix all of the packs losing capacity, and that some of the packs don't lose capacity quickly even with no BMS update. It's certainly an interesting situation. I personally don't trust Nissan here: either they are fumbling around like clowns, or they are try to deal with a large problem with small, relatively inexpensive band-aids.
 
LeftieBiker said:
The best theory here, IMO, is that there are both defective BMS units AND defective packs, and that Nissan has chosen to address only the former in order to save money.
1. Programming error
2. Poor QC
3. No TMS

Welcome all, to the LEAF life.
 
SageBrush said:
LeftieBiker said:
The best theory here, IMO, is that there are both defective BMS units AND defective packs, and that Nissan has chosen to address only the former in order to save money.
1. Programming error
2. Poor QC
3. No TMS

Welcome all, to the LEAF life.

TMS is not desirable to everyone.

Unlike good QC and good programming.

How's your Tesla stock doing today?

-5.22%? So sad. :cry:
 
SageBrush said:
LeftieBiker said:
The best theory here, IMO, is that there are both defective BMS units AND defective packs, and that Nissan has chosen to address only the former in order to save money.
1. Programming error
2. Poor QC
3. No TMS

Welcome all, to the LEAF life.
1) As opposed to bugs on Model 3's that cause 12 volts to run dead and be stuck in someone's garage like https://teslamotorsclub.com/tmc/threads/tesla-model-3-down-wont-power-up-and-is-inaccessible.108412/? He originally used the term "bricked" which bent some people out of shape and spurred all sorts of discussion/debate.

And putting out updates that cause stuff like this:
https://teslamotorsclub.com/tmc/threads/navigate-on-autopilot-is-useless-2018-42-3.134137/
https://teslamotorsclub.com/tmc/threads/unstable-on-2019-12-1-2.152200/

2) As opposed delivering or attempting to deliver cars to customers with obvious external build quality problems (misaligned panels, uneven panel gaps and some bad paint jobs):
https://teslamotorsclub.com/tmc/threads/red-paint-quality-issues.124897/
https://teslamotorsclub.com/tmc/threads/red-paint-quality-issues.124897/#post-2928970
https://teslamotorsclub.com/tmc/threads/is-my-car-the-one-with-worst-paint-job-and-service-center-help.133214/#post-3153143
https://teslamotorsclub.com/tmc/threads/staggering-amount-of-issues-found-at-after-delivery-considering-returning-the-car.128682/
along w/the plethora of people finding nibs in the paint, rejected deliveries, etc. I wish I could find the pics of the guy w/the black 3 where it looked like the paint guns had run out and there was large areas w/insufficient paint.

Here over a dozen folks w/failed Model 3 drive units within a certain window of time at https://teslamotorsclub.com/tmc/threads/shoddy-quality-and-poor-qc-and-missing-parts.117356/page-5#post-3516347. How many Leaf drive motors have been reported here replaced due to failure since Dec 2010?

Many Model 3 folks had defective turn signal modules which required replacement to correct: https://teslamotorsclub.com/tmc/threads/psa-left-turn-signal-doesnt-reset-defective-steering-control-module.129414/. My guess is that eventually, Tesla was more interested in shipping out the cars w/defective modules than holding them up for properly working ones.
 
Then we better consider the fact that Musk brags about not using automotive grade electronic components. Such as the 17 inch display in the Model S.

https://www.thedrive.com/tech/27989/teslas-screen-saga-shows-why-automotive-grade-matters
 
WetEV said:
Then we better consider the fact that Musk brags about not using automotive grade electronic components. Such as the 17 inch display in the Model S.

https://www.thedrive.com/tech/27989/teslas-screen-saga-shows-why-automotive-grade-matters

Yikes. I especially "like" the "Dogs & children" thermal protection that is really there just to protect the display screen, and will still kill the aforementioned dogs & children.
 
LeftieBiker said:
WetEV said:
Then we better consider the fact that Musk brags about not using automotive grade electronic components. Such as the 17 inch display in the Model S.

https://www.thedrive.com/tech/27989/teslas-screen-saga-shows-why-automotive-grade-matters

Yikes. I especially "like" the "Dogs & children" thermal protection that is really there just to protect the display screen, and will still kill the aforementioned dogs & children.

The formal name for it is "cabin overheat protection", which is different from dog mode (protects your dogs) and camper mode. The Drive piece simply found the non-altruistic justification for cabin overheat protection (which was deployed around Sept 2016). Once developed, dog mode and camper mode natually followed and offers better protection for the living things and aren't there to protect the screen.

Side note. I've seen my model 3 interior get to up 125F, and haven't seen any yellow banding yet. Probably needs a longer duration to take effect.
 
goldbrick said:
One possible scenario - and this is totally hypothetical ! - out of the millions or billions of possibilities would be something like the code had a bug that caused the system that read the battery voltage to not recalibrate itself as intended. So if the ADC that converts the battery voltage to a number for the BMS changed over time (and virtually all silicon devices change characteristics over time, temperature, use, etc) then the voltage reported to the BMS would be incorrect. Now imagine that there are multiple vendors and batches of these ADC parts. Then different cars would exhibit different behaviors over time. Fixing the software to recalibrate the part as needed would eliminate the problem and the BMS would get a more accurate reading of the actual battery voltage, as it would now be unaffected by the errors in the ADC.

Seriously doubt that system designers would not have the considered the potential of an ADC's reference voltage drift over time. Most likely
there's redundancy in the system to monitor that and correct for it. The key point, though, is that DAC functions today are integrated in the
microcontroller (processor) chips, e.g. used in the BMS and other vehicle ECUs. Furthermore, the supply voltages of processor chips are
very tightly regulated. Given the CAN bus system of present day vehicles, various ECUs can cross reference battery supply voltages,
e.g. VCM versus the BMS voltages as the ECUs communicate.

Most likely the BMS of the 30 kWh Leafs had the same firmware as the earlier Leafs, with just modifications to key parameters
for future battery upgrades being stored in flash RAM and easily updated via Nissan's Consult diagnostic tool. So it's highly doubtful
that only the 30 kWh Leaf's BMS had a firmware design problem that required an update. It's more likely an issue with the 30 kWh
battery and not an initial firmware design error nor an electronics problem. It would have been easy for Nissan to update the BMS
firmware to test for certain battery conditions/parameters that may only occur to some of the 30 kWh vehicles, and then only tweak
the necessary BMS parameters. If those vehicles never entered the modes tested for, the BMS firmware tweak (patch) wouldn't run.
 
sister-in-law's 2016 leaf SV just lost its 3rd bar. 50k+ miles on the odo. Spent the first 35k miles with a previous owner in Santa Clarita, was down 4 bars at the time of purchase last year. It got the BMS update right away, which restored 2-bars. I expect it to lose its fourth bar by the end of this year as summer hasn't even started yet.
 
Oils4AsphaultOnly said:
sister-in-law's 2016 leaf SV just lost its 3rd bar. 50k+ miles on the odo. Spent the first 35k miles with a previous owner in Santa Clarita, was down 4 bars at the time of purchase last year. It got the BMS update right away, which restored 2-bars. I expect it to lose its fourth bar by the end of this year as summer hasn't even started yet.

Yikes. Where does she live, and do you know the build date?
 
cwerdna said:
^^^
Good news is that they'll receive a replacement battery, and maybe even another one, if they're lucky.

It will be better news if they get a 2017 pack, and it lasts out the warranty with no more than one bar loss. We still don't know if the early 2016 30kwh packs just have a high rate for cell defects, or if they also have worse longevity.
 
LeftieBiker said:
Oils4AsphaultOnly said:
sister-in-law's 2016 leaf SV just lost its 3rd bar. 50k+ miles on the odo. Spent the first 35k miles with a previous owner in Santa Clarita, was down 4 bars at the time of purchase last year. It got the BMS update right away, which restored 2-bars. I expect it to lose its fourth bar by the end of this year as summer hasn't even started yet.

Yikes. Where does she live, and do you know the build date?

She lives 2 blocks from me. Will need to confirm the build date later.
 
cwerdna said:
^^^
Good news is that they'll receive a replacement battery, and maybe even another one, if they're lucky.

With my 2016 Leaf S as reference (35k miles and still with 12 bars), I doubt she'll make it to a third battery. I think the previous owner must've abused it (left it fully charged and parked under the sun or something like that).

But yes, getting a replacement battery towards the end of the warranty period is pretty good news.
 
LeftieBiker said:
cwerdna said:
^^^
Good news is that they'll receive a replacement battery, and maybe even another one, if they're lucky.

It will be better news if they get a 2017 pack, and it lasts out the warranty with no more than one bar loss. We still don't know if the early 2016 30kwh packs just have a high rate for cell defects, or if they also have worse longevity.

Build date of November 2015, so that would explain the rapid degradation.
 
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