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Wiki Sudden Loss Of Range With 2019.16.x Software
- Thread starter Dutchmeeuw
- Start date
All limits on li-ion batteries are "artificial" - for the purposes of safety and longevity - starting from the very day you pick up your car. That's the entire purpose of the bloody BMS. If any aspect of the battery worsens over time - which forces the limits that have been there since the very day you picked up your car to decline - that's known as degradation.
Saying "We're artificially capped" is like saying "I want to put more gas into this gas cylinder, but this stupid pressure limiter is preventing me! And now they're telling me that because my gas cylinder is old and rusty, they'll only fill it up to 80% as much as when it was new. Yeah, they told me that it would one day become old and rusty and not hold as much gas and that they offer no guarantee against its capacity being limited, but because I got this 80% limit thing all at once rather than gradually... LAWSUIT!"
Don't get me wrong, I fully agree that Tesla should be more transparent about these sort of things. They obviously don't want to talk about things like degradation, about charge limitation, etc - just like they didn't want to have to talk about performance limitations for motor longevity in the past. It's bad PR, so they try to do these things quietly. But bad PR or not, it's something that they really need to be open about.
While the warranty has no provision for range guarantees, I think a goodwill gesture would be to sell updated packs at-cost. So your old car ends up with the range of a new, top-of-the-line one. And the timing is great - with the current lower S/X sales rate, they should now have enough 18650 capacity to make more S/X packs for this purpose.
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Your translation is correct, but that doesn't explain the higher tapering at 80% and above. At this SoC, the cells should have reached the same temperature in both charging sessions.
Nevertheless, more feedback would certainly be helpful.
Having seen many hundreds of charging graphs for Teslas, I've seen charging results across the board. I've seen vehicles get consistently lower results than others, I've seen vehicles get randomly lower results than others, with no explanation for the random changes - sometimes permanently lower, sometimes jumping back up afterwards, with no explanation. I've seen chargers give consistently lower results than others at the same station with the same nameplate, stations get consistently lower results than others with the same nameplate, and I've also seen the same sort of lower results occur randomly with no explanation for the random changes... just suddenly, lower. Sometimes consistently lower after that, sometimes coming back up, with no rhyme or reason.
I've seen enough of this sort of stuff to know that you can't rate an update based on a single person's charging graph.
That said, it's certainly plausible that charge rates were limited. If lithium can't reliably intercalate faster than a given rate into the anodes, you don't want to try to force it. Intercalation is a physical limit; if you try to push past it, you'll be plating out lithium metal instead, which you don't want. The BMS always limits the charge rate for this purpose. The only thing Tesla could plausibly do to boost intercalation rates would be to increase the temperature, although that will shorten battery life via increased anode-electrolyte reactions.
Affected cars don't charge cells to 4.2V but 4.07V. No matter how much degradation there is, cells are always able to charge to 4.2V. Tesla limited this.
You say that like that's supposed to be a shock, or like it's supposed to change anything that I wrote.
The cells are not charged to their physical maximum voltage when new, either. It's the job of the BMS to impose limits.
It shows, that Tesla put artificial limit to battery.
Yes, that's what a BMS does, from day 1 of vehicle ownership. That's the very reason why the BMS exists - to impose artificial limits on the battery, for safety and longevity reasons.
There is always a spread between the behaviour of the different batteries (and some of it depends on environmental factors and charging history).
No manufacturer will guarantee that everyone gets above average batteries (they do sell outside of the Lake Wobegon area).
"Defective" is "outside of the normal range", but customers cannot at will define what range they would like to see means a battery is seen as "defective".
For model 3 owners, Tesla has been more careful to define what is definitely abnormal, and the bar is awfully low: 70% at the end of the warranty period, which is 8 years or 192000km, whichever comes first. They might treat customers skating close to that limit as "abnormal" once they gathered fleet data that allows them to more accurately see what is normal (and replace batteries when a user is seen as being in the 5% of unluckiest users), but they haven't put that stick in the ground.
Also, charging limits imposed when someone is worried about a hitherto unforeseen condtion are usually precautionary. Just hypotethically, suppose they see a rise in the risk of fire for some batteries, which could have lethal effects, I would rather want them use an abundance of caution in setting limits until they gathered more data, and only then attempt to restore more range to more customers. If someone dies, then that's not something you can fix by installing some new firmware.
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When for years cells were charged to 4.2V and then one day they are charged to 4.07V, this is not somethig, that was done from day 1 of vehicle ownership.
Would you rather the BMS not do its job?
If you want the BMS to do its job, do you not want it doing its job as well as possible, based on the best information available, including that accumulated after the first software release?
If information arrives later that the earlier version of the BMS should have been doing something different than it was initially programmed to be doing, do you not want it being updated to do what it should have been doing?
I'm sorry that you got bad luck with a battery whose longevity turned out to not be as good as some others. I really am. These were Tesla's first batteries with silicon in the anodes, and it became clear as soon as they started having to impose higher limitations on supercharging rates that their longevity was not holding up as well as Tesla anticipated. But the solution to the physical reactions taking place in the battery not being as good as hoped isn't "screw the BMS".
Maybe, however, you instead do want to say screw the BMS? Perhaps then Tesla should add a button, "Please tell my BMS to let me destroy my battery pack at an accelerated rate, and flag my vehicle to all potential buyers that I did this so that they know should I choose to sell it on the used market; I hereby acknowledge that I'm throwing safety and degradation to the wind"? Would that make you happy?
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I'm not affected. But it is not relevant.
Tesla has shipped defective batteries to some customers and obvious solution is to replace those batteries with new ones which are not defective. Batteries are under warranty.
Evidence, that those are defective batteries is, that this restriction is only applied to "small number of customers". If this were normal degradation, it would affect all.
You want Tesla to do replacements under warranty for things not covered by the warranty?
Even with the rate of range loss on these packs, they're still less degradation than the old Leafs. And you don't see Nissan rushing out to offer free upgrades on them.
You're a hair away from claiming that Tesla has a legal obligation to ship only batteries that are above average (and remain so forever). Welcome to Lake Wobegon.
The BMS should do it's job. It's not so much about what is technically appropriate. It's about what the proper commercial obligations by Tesla towards its early customers are. I can see this going very differently in different jurisdictions. Some may add weight to your assertions about P85D being a novel, young product and limit Tesla's liability. Some may add more weight to consumer protection and decide that Tesla continues to carry the full consequences of it's earlier estimates and (implied) promises.
But hopefully we can agree that part of a proper response would also be better communication about this issue. When we get reports of owners refusing to update their firmware because it might reduce range or charging speed, something is fundamentally broken in the way this was handled.
"Loss of Battery energy or power over time or due to or resulting from Battery usage is NOT covered under this Battery and Drive Unit Limited Warranty,"
I believe this restriction is placed because of spontaneous fires and the aforementioned excluding clause does not apply.
I believe this restriction is placed because of spontaneous fires and the aforementioned excluding clause does not apply.
Ferrycraigs
Member
I have told my local Service Centre I don't want money, or a new battery, I just want the restriction lifted on my old battery. I would have thought that must be almost a cost free option. But their resistance remains robust. And as their answers are invariably taken from a pre-prepared statement, not always directly relevant to my case, I do wonder if Tesla has issued a 'reject all claims' policy.
Ferrycraigs
Member
Reports in the UK suggest the latest updates show 'some' recovery, a little more back each time. But I don’t want some of it back, I want all of it back. I remember I was asked to pay for all of it when I bought it.
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