Wiki Sudden Loss Of Range With 2019.16.x Software

[PaulusdB]

That certainly sounds like it fits what we have seen. @wk057 any chance you can confirm that is what you thought condition Z might be?

Isn't it considered bad form to comment on ones own postings?

 

[AmpedRealtor]

What has the response been to the class action? Anyone?

 

[mjmiron]

What has the response been to the class action? Anyone?

Krickets

 

[MP3Mike]

Isn't it considered bad form to comment on ones own postings?

Huh? I didn't comment on my own posting, and I asked WK057 to comment on Alchemsits42's post...

 

[mjmiron]

I think the reduction in capacity is affecting everyone.

 

[MP3Mike]

What has the response been to the class action? Anyone?

Class actions move slow. Expecting a response already is just silly.

 

[Droschke]

Hi everyone,

I've been a longtime silent lurker, but this topic certainly has grabbed my attention a lot and so I decided to make a lengthy post in the German Tesla forum (tff-forum.de) a few days back. It was well recieved and several members suggested I also post my findings here, which is what I'm going to do now.

Short background about myself: I have a MSc in chemistry with focus on functional materials and while my research topic right now is not about batteries, I regularly read research about Li-ion technology and consider myself to beat least somewhat knowledgeable in the topic. I also tinker with some applications for 18650 cells as a hobby and regularly read some discussions in the Second Life Storage forum where members are making stationary solar storage and similar things from discarded laptop and tool batteries. Whether this makes sense or is safe might be worthy of discussion, however you cannot deny that the members have collected a lot of knowledge about failure modes of 18650 batteries over the years.

Anyway, all the talk about Li plating and dendrite formation reminded me about a well-known problem in that community. A few years back, many members started to notice that older Sanyo 18650 cells often start to heat up upon charging. The cell looks fine at first glance (normal voltage, low internal resistance, reasonable capacity) and starts the charging process normally. However, once the charge voltage reaches around 4.0V, the cell begins heating up, often leading to dangerously hot temperatures of 80°C or higher. The reason is a parasitic internal current that soon exceeds the charging current making a full charge impossible. At first, only Sanyo UR18650A cells seemed to be affected, however by now examples are known from nearly all older Sanyo cell types as well as some Panasonic, Sony and LG batteries. All reasoning about the underlying causes was speculation until one member who investigated the problem on his job posted one very interesting contribution: Red Sanyo 18650 Cells Getting Hot While Charging - Page 10
Short summary: If charging conditions deviate a little bit from the norm (temperature too high, too much time spent at high SoC), micro-dendrites form between cathode and anode, leading to an internal short-circut. This is the exact failure mode of Li plating. The effect usually vanishes after cooling down and the cells stabilize between 3.95 and 4.05V. It might even disappear completely for a few cycles, but eventually always comes back. Also, the onset is relatively independent from age (both temporal and cycling) and can occur as early as after one year. The effect starts to manifest as an elevated self-discharge rate and worsens from there. As a safety measure, the original poster recommends charging only to 4.10V (corresponds to a "standard charge" in Tesla terms) and reducing charging current and temperature while charging. No failures were observed with these precautionary measures.

Let's just hypothetically assume, Tesla found exactly such a problem in some batteries. How would that manifest?

- Balancing problems and self-discharge at high SoCs lead to some cars being unable to charge to 100%
- High SoCs suddenly make the cooling system work much more than usual due to heat generation
- In the worst case, single cells cross the threshold to thermal runaway and cause cars to burn up
- Tesla takes notice and distributes new software that looks for elevated self-discharge and sets charging voltage to 4.1V or lower on those cars. DC charging speed is reduced for all cars as a precautionary measure.

Correct me if I' wrong, but this seems to be pretty much exactly what is happening.

I will tell you in all honesty: As a Tesla fan, having ordered a Model 3 and holding TSLA shares, I very much hope that Tesla will find a solution to the problem. But everything looks very sketchy. Not only for Tesla, but for a lot of others as well. Panasonic might have to take partial blame - they must have known about the safety problems with their UR18650 cells for at least ten years, but never even notified their customers. And most other battery giants have been shown to deliver cells with similar problems (albeit not in the magnitude seen at Sanyo). I wish Tesla would just come forward with a meaningful statement.

I want to make clear that I do absolutely not suggest that most older Tesla packs are defective or dangerous. If I had to guess I would think that in very few select cases, problems as described above were observed and Tesla, fearing a PR nightmare, decided to play it safe with all packs that even remotely look like they might develop that issue in the future while they are working on a tool to reliably weed out any seriously damaged packs. Tesla batteries have been shown to be able to lead long and safe lives with minimal degradation repeatedly. A few black sheep do not change that big picture, as long as Tesla is able to identify them correctly.

What are your opinions?

Thanks for reviving this thread with more technical insight.

Reading your feedback and the linked secondlifestorage.com post, and besides the 4.1V being a safer upper limit, the higher temperature during charging sessions seems to be indicated as the risk factor. If you have read the earlier posts by the those who seem also knowledgeable in battery technologies, the risk was defined as charging in colder temperatures. This was mentioned several times as I recall. An average owner, like myself, should surely be even more confused at this time.

 

[Alchemist42]

Thanks for reviving this thread with more technical insight.

Reading your feedback and the linked secondlifestorage.com post, and besides the 4.1V being a safer upper limit, the higher temperature during charging sessions seems to be indicated as the risk factor. If you have read the earlier posts by the those who seem also knowledgeable in battery technologies, the risk was defined as charging in colder temperatures. This was mentioned several times as I recall. An average owner, like myself, should surely be even more confused at this time.

To be honest, this threw me off a bit as well. Unfortunately, I have no further source on the Sanyo case apart from that post and a bit of personal experience with affected cells. However, it is true that Sanyo changed the specified maximum charging temperature from 45°C to 40°C and I know that several manufacturers recommend charging to 4.2V only in a narrow window. For example, Samsung has a window between 10°C and 45°C for 4.2V charging, above and below it recommends 4.1V. (Source: Datasheet of Samsung INR21700-48G cell, roughly comparable with the M3 cells capacity-wise). So it might very well be that charging always needs to take place in a "Goldilocks Zone" of sorts.

 

[swegman]

What has the response been to the class action? Anyone?

Based on my conversation with the attorney a couple of days ago, he has gotten numerous engagement letters from clients and is in discussions with many, many more potential clients. The complaint was not yet served on Tesla when we spoke.

I’m still on the fence, waiting to see how much mileage is recovered with software 2019.28.2.5. I had my car at Tesla today and requested that they perform the CAC test on the battery but they declined to do it. They said Tesla wants to wait on the test as long as mileage is being recovered. Once mileage stops being added to the battery they said they will revisit the request for the test.

 

[lightningltd]

Based on my conversation with the attorney a couple of days ago, he has gotten numerous engagement letters from clients and is in discussions with many, many more potential clients. The complaint was not yet served on Tesla when we spoke.

I’m still on the fence, waiting to see how much mileage is recovered with software 2019.28.2.5. I had my car at Tesla today and requested that they perform the CAC test on the battery but they declined to do it. They said Tesla wants to wait on the test as long as mileage is being recovered. Once mileage stops being added to the battery they said they will revisit the request for the test.

I am still on the fence as well, hoping they might do the right thing and give back what they stole, but this slow charging REALLY sucks
I should start billing them for the extra charging time at the standard shop rate.

 

[Droschke]

To be honest, this threw me off a bit as well. Unfortunately, I have no further source on the Sanyo case apart from that post and a bit of personal experience with affected cells. However, it is true that Sanyo changed the specified maximum charging temperature from 45°C to 40°C and I know that several manufacturers recommend charging to 4.2V only in a narrow window. For example, Samsung has a window between 10°C and 45°C for 4.2V charging, above and below it recommends 4.1V. (Source: Datasheet of Samsung INR21700-48G cell, roughly comparable with the M3 cells capacity-wise). So it might very well be that charging always needs to take place in a "Goldilocks Zone" of sorts.

Thanks.

But I thought that is exactly what the Tesla's BMS and the cooling/heating management features of the Tesla battery packs supposed to do, that is keeping the pack temperature within the acceptable limits in order to charge to 4.2V.

Am I wrong?

 

[Droschke]

I had my car at Tesla today and requested that they perform the CAC test on the battery but they declined to do it. They said Tesla wants to wait on the test as long as mileage is being recovered.

Interesting. Did the SC know about some mileage being recovered for some impacted cars and brought it up to your attention on their own or you had informed them about it and they were using it to deflect your request?

 

[scottm]

Hi everyone,

DC charging speed is reduced for all cars as a precautionary measure.

Correct me if I' wrong, but this seems to be pretty much exactly what is happening.

Not all cars have gotten reduced DC charge speed.

 

[scottm]

I think the reduction in capacity is affecting everyone.

By affected, do you mean anxiety in general ... about these electric cars we have... (applies to me)

Or affected as in reduced range? (I have 16.3 and have not seen range reduction)

 

[Droschke]

Not all cars have gotten reduced DC charge speed.

You are capacity capped but not charging speed capped?

 

[scottm]

I knew Tesla shoulda sold every car capped at 4.1v and never talked about it.

They needed an upper buffer for a couple good reasons, and the best reason seems to be "shouldn't have ever let the customers charge to 100" which is where the damage happens.

That slider should have been a hard stop at 90. Which, of course, would have read "100%"

 

[scottm]

You are capacity capped but not charging speed capped?

I am "unaffected" by the 16.x problem. If this includes 16.3, which is where I'm at.

Did not see a drop.

 

[Droschke]

I am "unaffected" by the 16.x problem. If this includes 16.3, which is where I'm at.

Did not see a drop.

Great.

In response to @Alchemist42, you said "Not all cars have gotten reduced DC charge speed."

But those cars that are capacity capped are also reporting charging speed cap. Of course not "all cars" seeing charging speed reduction.

 

[Droschke]

I knew Tesla shoulda sold every car capped at 4.1v and never talked about it.

They needed an upper buffer for a couple good reasons, and the best reason seems to be "shouldn't have ever let the customers charge to 100" which is where the damage happens.

That slider should have been a hard stop at 90. Which, of course, would have read "100%"

And may be they should also go easier with this risky higher speed charging escapade till they have their act together.

 

[swegman]

Interesting. Did the SC know about some mileage being recovered for some impacted cars and brought it up to your attention on their own or you had informed them about it and they were using it to deflect your request?

They know exactly how much you charge, whether it’s AC or DC and to what level the car was charged. So they could see that I always charge to 89% indicated range and that the rated miles for 89% has increased slightly.