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Wiki Sudden Loss Of Range With 2019.16.x Software
- Thread starter Dutchmeeuw
- Start date
Looks like you are toggling between wh/mi and wh/km.
oops....I have Model 3...Sorry....looks like I screwed up and posted in wrong forum....sorry
155-179 wh/mi on a 85 battery would equal almost double the distance that I can go on a charge. Something doesn't make sense in that statement or I am not understanding. Also I am averaging roughly 325 wh/mi and my full battery currently claims 255 miles. I am on 2019.28.3.1 no issues that I have noticed charging or supercharging car has just over 80k miles now 2014 S85. Although I don't believe I have had an issue and have always had good service this battery capping is not ok to do without compensating and explaining. My decision to buy a new X for my wife has now been delayed/cancelled depending on how Tesla handles this. Previously I have always had good things to say about the company. Now it's just I like my car.
let me go look again...I might have transposed thing....
OK...her is what I have.......2200 miles......525kWh...... 250Wh/mi
Does this make sense?
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?
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?
KidDoc
Member
I think
I think this is exactly what has happened. It is summer here in Texas and sure it is running a smidge over 100 most days but my cooling system has been running very loudly when charging in the garage much more so than the last 4 years. I think they adjusted the charge rate and decreased the maximum tolerated temperature at least with this 85 kw packs.
My 90% this morning was 227 rated miles @ 85k miles on the car. It was 215ish a few weeks ago, before the June decrease it was 228-230 so I seem to have recovered just about all of my capped energy.
I have not super charged so cannot comment on that, just charging at home @ 40 amp.
Software was updated this week to 2019.28.3.1
I think this is exactly what has happened. It is summer here in Texas and sure it is running a smidge over 100 most days but my cooling system has been running very loudly when charging in the garage much more so than the last 4 years. I think they adjusted the charge rate and decreased the maximum tolerated temperature at least with this 85 kw packs.
My 90% this morning was 227 rated miles @ 85k miles on the car. It was 215ish a few weeks ago, before the June decrease it was 228-230 so I seem to have recovered just about all of my capped energy.
I have not super charged so cannot comment on that, just charging at home @ 40 amp.
Software was updated this week to 2019.28.3.1
There's at least one report somewhere in the last 200 pages of this thread with a canbus scan showing that peak current was not reduced, so the only thing causing loss of power vs before 16.1 is the cap in charging. i.e. every SOC percent displayed now is less than the true SOC of the battery as compared to before 16.1.
They did not throttle power. Lower power is the result of not being able to charge as high, so if when you charge to 90%, you're really only charging to 80%, then you have the same power you would have had had you charged to 80% before 16.1.
As longs as what you mean is the power is lower as a byproduct of simply not being able to charge as high, then I agree but I just want to make sure you're not stating something else.
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Are both your cooling louvers opening up when you supercharge?
I charge at home as well and mileage before update at 90% was 234 and then after June update went to 210. As of yesterday was 225 and when I charged this morning 220 so fluctuated a little. I too charge at home but at 32amps max and don't super charge but maybe 2-3 times a month.
Thank you for the educated information.
But is this a problem only with 18650 batteries, or does it also affect 2170 batteries?
Tesla official statement says this happened to "a very small percentage of owners...." How do you or anyone knows how many?
You might be right, or you might be wrong. That is irrelevant. The "Black sheep" you described did not get what they bargained for. Those who got black sheep need full restitution of what they paid for !!!
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?
Whether a pack is likely to be affected depends very much on the battery chemistry, the form factor has a negligible influence. Li plating and dendrite formation is a possible failure mode for all Li batteries, but obviously one of the deadliest. This is why most companies today put great effort into measures to migitiate that possibility. I have to assume that research progress has made it much less likely for newer cells (for example, starting with the 90kWh batteries, the anode contains silicon that lowers the electrode potential and allows for easier intercalation of Li+, as already mentioned some pages before). The exact way manufacturers are combatting this and other failure modes is strictly secret, however. So long story short - Newer batteries are probably much less likely to suffer from such a condition.
bhtooefr
Active Member
Presumably that particular type of defect would happen with any cylindrical (and possibly any) cells of a given specific chemistry, independent of the form factor.
And, as a 21700 is a larger diameter cell, it'll have a harder time shedding heat from the interior, possibly making it more susceptible to any heat-based effects, especially if they're based on a given cell surface temperature (potentially a higher interior temperature for the same surface temperature).
But, of course, if the chemistry or construction method (as opposed to size, a 21700 uses the same construction method as a contemporary 18650) of the cell changes, then so does the failure - whether it happens and how severe it is.
And, as a 21700 is a larger diameter cell, it'll have a harder time shedding heat from the interior, possibly making it more susceptible to any heat-based effects, especially if they're based on a given cell surface temperature (potentially a higher interior temperature for the same surface temperature).
But, of course, if the chemistry or construction method (as opposed to size, a 21700 uses the same construction method as a contemporary 18650) of the cell changes, then so does the failure - whether it happens and how severe it is.
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