Wiki Sudden Loss Of Range With 2019.16.x Software

[Droschke]

I was asked by a friend for further explanation on the volts bit, as he was sure from his school days that volts in a cell do go up and down. But I was saying they don’t. He is correct. Yes they do. The volts I am talking about, in relation to the degradation point, is an upper limit rather than the amount of charge a cell stores.

There are two separate issues here. The amount of volts that the cell is designed to accept, ie the range of charge. And the amount of charge a cell is actually holding at any one time. They are related but different, but it’s easy to see why there might be confusion.

First one: the Volts each cell is designed to accept. A battery is designed to accept a range of energy, ie the range between empty and full. If it takes on too much, or loses too much, it damages the cell. So BMS software sets an upper and lower level. There is a maximum figure (Vmax) and a minimum figure (Vmin). Although it’s a poor example, think of it like a fuel tank. When all the cells are at Vmax, the total charge (in a 70 kWh battery) equals 70 kWhs. And when it’s at Vmin, the available charge is 0 kWhs. But if you change the Vmax to a lower figure, (which is what Tesla appear to have done) then the tank is suddenly smaller. So it’s a bit like changing a 70 gallon tank for a 60 gallon tank. Then when the customer complains that the car won’t go as far, the maker says, nothing is wrong, your fuel tank is healthy, it’s just normal wear and tear from driving. You are still getting the same range as other cars of your age and mileage. Erm no. It’s because the size of the fuel tank has been changed. And just like Volt Capping, however much the engine wears out, the fuel tank still stays the same size. This is why volt capping isn’t degradation. Volt capping is changing the size of the fuel tank. Degradation, however severe, will not change Vmax. That can only be done artificially.

Second one: How much the cell holds, sometimes referred to as Open Circuit Voltage, is entirely dependant on the State of Charge. At full SoC it should hold 4.2V. At low SoC it may only hold 3.1V or so. In a badly degraded battery, whilst it will still try to charge up to 4.2V, it may not manage. But the 4.2V limit will still be there. Which is why in older EVs, the max charge reduces to a figure below 100%.

So, yes, the voltage in an individual cell certainly does go up and down. And degradation will have an effect on that. Voltage capping is just changing the size of the fuel tank. Reducing the size of the fuel tank (battery) reduces the battery's available capacity, which in turn produces less range. But this sudden loss has nothing to do with degradation. It’s to do with the sudden reduction in the size of the fuel tank.

Hope that helps.

@Ferrycraigs, thanks for your diligence and yet another clarification. And my sincere apologies in advance for going a bit off topic, even though helpful, but did you know this:

Yes, Flat-Earthers Really Do Exist

 

[Jkr85]

After reading 7000+ posts I am wondering: has this thread sufficiently degraded to be capped?

 

[Ferrycraigs]

@Ferrycraigs, thanks for your diligence and yet another clarification. And my sincere apologies in advance for going a bit off topic, even though helpful, but did you know this:

Yes, Flat-Earthers Really Do Exist

Ha! I used to live in Alberta. Our house was on the edge of the prairie. We could actually see the curvature if the earth from our house. Curious place therefore to hold a Flat Earth seminar.

 

[Ferrycraigs]

After reading 7000+ posts I am wondering: has this thread sufficiently degraded to be capped?

But wouldn’t that restrict our range?

(Of topics)

 

[Chaserr]

Ut Oh, You may have given them the recipe to cook your goose. Maybe get one of those lead lined vests from the dentists office for your mirror. Hmm, I was joking, but actually wish I would have tried it now. Fight on, do not become assimilated.

Considering the lengths they have gone to update people manually so they don't have to publicly disclose how important they think the downgrade imposing updates are, I'd consider unplugging the antenna to keep out of the manual updates. It sounds like recent updates were rewritten to ignore unplugged seats so they're reading the forums and trying to force updates without telling us why they think it's so important. I hope we get to read some of the NHTSA notes on the updates themselves, they asked for exactly the right info.

 

[Leeboy22001]

According to TeslaFi battery report, I've lost an additional 2km range with the upgrade to v10. That's probably within the margin of error, however, I'll do a 'useable kW' calculation and report back. Other Aussie owners with affected cars are also reporting a further reduction with v10 software

I've also noticed further range reduction since V10 . I'm using CAN bus data, My S60 typical has dropped from 169 to 166, and total capacity has dropped from 51.4kWh to 50.7Kwh. Just before V10 capacity fluctuated from 51.2 to 51.6Kwh, never went below 51.2, so this is real ! . The lowest it got to was 49.2 after the infamous May update.

Also I've only used SuC twice in the last 3 months, the rest has been home AC charging to 90%.

 

[BPeter]

No he's wrong and you're correct. A degraded battery has roughly the same wh/mile but less usable capacity when charged to the original 4.2v 100% value.



Right. It knows it reached 100% because the cells report 4.2v and volts are the way the BMS determines charge %. If it can't charge as many kWh at 100% as it used to, it recalculates usable capacity.

Who handles the first post wiki? That line should probably be edited or removed.

 

[_jal_]

I was asked by a friend for further explanation on the volts bit, as he was sure from his school days that volts in a cell do go up and down. But I was saying they don’t. He is correct. Yes they do. The volts I am talking about, in relation to the degradation point, is an upper limit rather than the amount of charge a cell stores.

There are two separate issues here. The amount of volts that the cell is designed to accept, ie the range of charge. And the amount of charge a cell is actually holding at any one time. They are related but different, but it’s easy to see why there might be confusion.

First one: the Volts each cell is designed to accept. A battery is designed to accept a range of energy, ie the range between empty and full. If it takes on too much, or loses too much, it damages the cell. So BMS software sets an upper and lower level. There is a maximum figure (Vmax) and a minimum figure (Vmin). Although it’s a poor example, think of it like a fuel tank. When all the cells are at Vmax, the total charge (in a 70 kWh battery) equals 70 kWhs. And when it’s at Vmin, the available charge is 0 kWhs. But if you change the Vmax to a lower figure, (which is what Tesla appear to have done) then the tank is suddenly smaller. So it’s a bit like changing a 70 gallon tank for a 60 gallon tank. Then when the customer complains that the car won’t go as far, the maker says, nothing is wrong, your fuel tank is healthy, it’s just normal wear and tear from driving. You are still getting the same range as other cars of similar age and mileage. Erm no. It’s because the size of the fuel tank has been changed. And just like Volt Capping, however much the engine wears out, the fuel tank still stays the same size. This is why volt capping isn’t degradation. Volt capping is changing the size of the fuel tank. Degradation, however severe, will not change Vmax. That can only be done artificially.

Second one: How much the cell holds, sometimes referred to as Open Circuit Voltage, is entirely dependant on the State of Charge. At full SoC it should hold 4.2V. At low SoC it may only hold 3.1V or so. In a badly degraded battery, whilst it will still try to charge up to 4.2V, it may not manage. But the 4.2V limit will still be there. Which is why in older EVs, the max charge reduces to a figure below 100%.

So, yes, the voltage in an individual cell certainly does go up and down. And degradation will have an effect on that. Voltage capping is just changing the size of the fuel tank. Reducing the size of the fuel tank (battery) reduces the battery's available capacity, which in turn produces less range. But this sudden loss has nothing to do with degradation. It’s to do with the sudden reduction in the size of the fuel tank.

Hope that helps. Sorry if I have caused confusion.

A lot of this is very counterintuitive and it takes careful study to understand and why. I spent a lot of time in college chemistry understanding why cell voltage is only barely changed by electrolyte concentration for instance. It’s not exactly the same as the many modes of degradation in LiIon batteries, but it’s probably analogous. (I just felt the first thrown stone hit my head ) I always felt like the concentration of ions in the electrolyte should massively affect voltage, but it doesn’t. It only affects voltage measured across the terminals because the resistance of the electrolyte changes.

ultimately the voltage across the battery is determined by the electropotential difference of the anode and cathode. That potential is after all what gives the battery voltage (a measure of potential). At the end of the day, as long as the chemical composition of anode and cathode stay the same, the voltage across the battery will remain the same for a given state of charge. Only it’s ability to generate current will change as more or fewer (fewer in the case of degeneration) ions are able to participate in the exchange of electrons

 

[Droschke]

Who handles the first post wiki? That line should probably be edited or removed.

Are you talking about what @Dutchmeeuw, the original poster wrote, or somewhere else in the wiki part? Copy/pasting the line in your response would be useful.

 

[Guy V]

Which sentence in the warranty do you think makes it warrantable? This clear sentence below indicates that battery degradation caused by usage is specifically non-warrantable. You just simply can't ignore that language or pretend that it doesn't exist.

"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"



Usage doesn't "nullify" the warranty -- but loss of energy or power resulting from usage (e.g., lithium plating) is simply not covered.



I don't know who stated that the damage (e.g., lithium plating damage due to usage) results in a reduced possible maximum voltage on the anode.

Instead it seems to me that when certain damage (perhaps due to usage?) is identified (e.g., by measuring Condition Z to see if it reaches a trigger level?) then the BMS takes action (like it does in response to many other triggers) and limits to voltage.



except when lithium plating causes voltage plateaus?



exactly.



What Tesla offered, in black and white plain english was a "limited" warranty. And one of the limits was:
"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"

What you have to do is find facts to support is that Condition Z reaching the trigger level is a warrantable manufacturing defect or a battery failure rather than simply battery wear from usage, such as lithium plating. I see no evidence supporting that yet but it is entirely possible.

So far it all points towards wear from usage, probably lithium plating, since only relatively few batteries are affected, rather than lots of them. And the affected batteries do not seem to be from a particular batch of batteries (which would suggest a manufacturing defect) but rather are spread out with no pattern discerned.

Tesla is legally bound by ALL of Elon's public statements.

 

[bhzmark]

Tesla has enough knowledge of the state of the art to know how to design their BMS to make plating a very slow process.

And also developing knowledge to perhaps remediate or slow it down once it occurs.

Tesla has enough knowledge of the state of the art to know how to design their BMS to make plating a very slow process. That they didn't do this constitutes a mistake. Per their advertisements for their cars, mistakes made by Tesla or the user are fully covered under the warranty.

It would be nice for people to actual provide specific citation and quotes.

Finally, "usage" won't hold up in court. In court the conversation will quickly move to "reasonable". That is, what damages are considered reasonable as arises from normal usage? Everything else is a defect. It would be hard to prove, but one could prove Tesla made an error which caused ureasonable damage due to normal usage.

Again, it would be nice to provide specific citations. For instance this citation:

The district court ruled correctly in dismissing the claims against Honda for breach of express warranty. Robinson's claim fails to allege that his minivan did not conform to the warranty. By its own terms, the warranty clearly, unambiguously, and repeatedly excludes tires from the warranty coverage. In the “A Quick Reference to Warranty Coverages” section at the beginning of the warranty booklet, under the heading “New Vehicle Limited Warranty,” the text states, “Every new Honda is covered, except for tires, for 3 years or 36,000 miles. The tires are warranted separately.” J.A. 48. In the subsequent, expanded description of the New Vehicle Limited Warranty, the booklet states that “This New Vehicle Limited Warranty Does Not Cover: Emissions control systems, Accessories, Batteries, or Tires. (They have their own warranties).” J.A. 53. Farther along, an entire page in the warranty booklet is devoted to “Tires.” This section explains that “[t]he tires that come as original equipment on your new Honda are warranted by their manufacturer.... A separate warranty statement for the tires is in the glove box.” J.A. 70. This section also makes clear that “a local representative of the tire's manufacturer”—not the Honda dealer—will be responsible for providing “warranty service.” Id.
Robinson does not dispute these terms in the warranty booklet. Instead, he points to other language in the warranty booklet which declares that “y keeping your Honda in top condition, you will be rewarded with years of trouble-free service at the lowest operating cost. The keys to keeping your Honda in top condition are proper operation and regular maintenance.” J.A. 79. Since Robinson alleges that he had all of the recommended maintenance performed by his Honda dealer, he asserts that the need to replace the tires after 18 months and 18,000 miles breaches Honda's express promise that he would be “rewarded with years of trouble free service at the lowest operating cost.”
However, even assuming that this phrase is not mere puffery, because the warranty expressly and repeatedly excludes tires from coverage, applying this provision to the tires is inconsistent with the specific terms of the warranty. In addition, “lowest operating cost” is not the same as “no operating cost,” and the purpose of the warranty section at issue here is to encourage owners to take care of their minivans to minimize future maintenance expenses. The phrase “lowest operating cost” implies that there will be some operating cost, even for a minivan that is kept “in top condition.” J.A. 79. Despite Robinson's alleged tire expenses, his well-maintained van most likely has the “lowest operating cost” when compared to other Honda Odyssey Touring model minivans that were not regularly serviced. Robinson v. Am. Honda Motor Co., 551 F.3d 218, 223 (4th Cir. 2009)​

The Tesla warranty clearly excludes loss of range and power due to usage and no amount of foot-stamping denial or conclusory assertions will change the text in the warrant.

You have to argue that Condition Z is a defect or failure. It is amusing that you are so afraid to even entertain that idea or say anything specific about it.

Why are you so afraid to deal head on with the point that the BMS is addressing the lithium plating which is from usage. Knocking down dozens of straw men arguments that ignore that point only demonstrate your inability to reconcile the likely BMS mitigation of the lithium plating wear, with the warranty limitations.

 

[DJRas]

And also developing knowledge to perhaps remediate or slow it down once it occurs.



It would be nice for people to actual provide specific citation and quotes.



Again, it would be nice to provide specific citations. For instance this citation:

The district court ruled correctly in dismissing the claims against Honda for breach of express warranty. Robinson's claim fails to allege that his minivan did not conform to the warranty. By its own terms, the warranty clearly, unambiguously, and repeatedly excludes tires from the warranty coverage. In the “A Quick Reference to Warranty Coverages” section at the beginning of the warranty booklet, under the heading “New Vehicle Limited Warranty,” the text states, “Every new Honda is covered, except for tires, for 3 years or 36,000 miles. The tires are warranted separately.” J.A. 48. In the subsequent, expanded description of the New Vehicle Limited Warranty, the booklet states that “This New Vehicle Limited Warranty Does Not Cover: Emissions control systems, Accessories, Batteries, or Tires. (They have their own warranties).” J.A. 53. Farther along, an entire page in the warranty booklet is devoted to “Tires.” This section explains that “[t]he tires that come as original equipment on your new Honda are warranted by their manufacturer.... A separate warranty statement for the tires is in the glove box.” J.A. 70. This section also makes clear that “a local representative of the tire's manufacturer”—not the Honda dealer—will be responsible for providing “warranty service.” Id.
Robinson does not dispute these terms in the warranty booklet. Instead, he points to other language in the warranty booklet which declares that “y keeping your Honda in top condition, you will be rewarded with years of trouble-free service at the lowest operating cost. The keys to keeping your Honda in top condition are proper operation and regular maintenance.” J.A. 79. Since Robinson alleges that he had all of the recommended maintenance performed by his Honda dealer, he asserts that the need to replace the tires after 18 months and 18,000 miles breaches Honda's express promise that he would be “rewarded with years of trouble free service at the lowest operating cost.”
However, even assuming that this phrase is not mere puffery, because the warranty expressly and repeatedly excludes tires from coverage, applying this provision to the tires is inconsistent with the specific terms of the warranty. In addition, “lowest operating cost” is not the same as “no operating cost,” and the purpose of the warranty section at issue here is to encourage owners to take care of their minivans to minimize future maintenance expenses. The phrase “lowest operating cost” implies that there will be some operating cost, even for a minivan that is kept “in top condition.” J.A. 79. Despite Robinson's alleged tire expenses, his well-maintained van most likely has the “lowest operating cost” when compared to other Honda Odyssey Touring model minivans that were not regularly serviced. Robinson v. Am. Honda Motor Co., 551 F.3d 218, 223 (4th Cir. 2009)​

The Tesla warranty clearly excludes loss of range and power due to usage and no about of foot-stamping denial or conclusory assertions will change the text on the page. You have to argue that Condition Z is a defect or failure. It is amusing that you are so afraid to even entertain that idea or say anything specific or intelligent about it.

Why are you so afraid to deal head on with the point that the BMS is addressing the lithium plating which is from usage. Knocking down dozens of straw men arguments that ignore that point only demonstrate your inability to reconcile the BMS mitigation of the lithium plating wear with the warranty limitations.

It also doesn't matter all your own foot stomping about the specific wording of their warranty (which few people have received on paper).
It WILL be up to the courts.
The Magnuson Moss Warranty Act is a great place to review what is and is not acceptable practice.

 

[cpa]

And also developing knowledge to perhaps remediate or slow it down once it occurs.



It would be nice for people to actual provide specific citation and quotes.



Again, it would be nice to provide specific citations. For instance this citation:

The district court ruled correctly in dismissing the claims against Honda for breach of express warranty. Robinson's claim fails to allege that his minivan did not conform to the warranty. By its own terms, the warranty clearly, unambiguously, and repeatedly excludes tires from the warranty coverage. In the “A Quick Reference to Warranty Coverages” section at the beginning of the warranty booklet, under the heading “New Vehicle Limited Warranty,” the text states, “Every new Honda is covered, except for tires, for 3 years or 36,000 miles. The tires are warranted separately.” J.A. 48. In the subsequent, expanded description of the New Vehicle Limited Warranty, the booklet states that “This New Vehicle Limited Warranty Does Not Cover: Emissions control systems, Accessories, Batteries, or Tires. (They have their own warranties).” J.A. 53. Farther along, an entire page in the warranty booklet is devoted to “Tires.” This section explains that “[t]he tires that come as original equipment on your new Honda are warranted by their manufacturer.... A separate warranty statement for the tires is in the glove box.” J.A. 70. This section also makes clear that “a local representative of the tire's manufacturer”—not the Honda dealer—will be responsible for providing “warranty service.” Id.
Robinson does not dispute these terms in the warranty booklet. Instead, he points to other language in the warranty booklet which declares that “y keeping your Honda in top condition, you will be rewarded with years of trouble-free service at the lowest operating cost. The keys to keeping your Honda in top condition are proper operation and regular maintenance.” J.A. 79. Since Robinson alleges that he had all of the recommended maintenance performed by his Honda dealer, he asserts that the need to replace the tires after 18 months and 18,000 miles breaches Honda's express promise that he would be “rewarded with years of trouble free service at the lowest operating cost.”
However, even assuming that this phrase is not mere puffery, because the warranty expressly and repeatedly excludes tires from coverage, applying this provision to the tires is inconsistent with the specific terms of the warranty. In addition, “lowest operating cost” is not the same as “no operating cost,” and the purpose of the warranty section at issue here is to encourage owners to take care of their minivans to minimize future maintenance expenses. The phrase “lowest operating cost” implies that there will be some operating cost, even for a minivan that is kept “in top condition.” J.A. 79. Despite Robinson's alleged tire expenses, his well-maintained van most likely has the “lowest operating cost” when compared to other Honda Odyssey Touring model minivans that were not regularly serviced. Robinson v. Am. Honda Motor Co., 551 F.3d 218, 223 (4th Cir. 2009)​

The Tesla warranty clearly excludes loss of range and power due to usage and no about of foot-stamping denial or conclusory assertions will change the text on the page. You have to argue that Condition Z is a defect or failure. It is amusing that you are so afraid to even entertain that idea or say anything specific or intelligent about it.

Why are you so afraid to deal head on with the point that the BMS is addressing the lithium plating which is from usage. Knocking down dozens of straw men arguments that ignore that point only demonstrate your inability to reconcile the BMS mitigation of the lithium plating wear with the warranty limitations.

Your cite is not on point. You are referencing a warranty claim against Honda regarding tires which have their separate warranty by the tire manufacturer, not Honda. Please find a cite that is clearly on point. My guess that there are not any, and this is why Tesla is digging its heels in, and the plaintiff is forcing the issue.

I think many on here have argued that this mysterious Condition Z is a defect or failure. If wk057 is to be believed, this was a serendipitous discovery by Tesla as they were looking for Condition X. This Condition Z was deemed important enough to start the dominoes falling. Apparently, Tesla was unaware of the possibility of Condition Z from the start. Would Tesla have sold us these batteries from day one as originally configured had they known about Condition Z in 2011-2012? Or would Tesla have altered the chemistry, BMS, enlarged the packs, whatever to sell cars with stated range and Supercharger speeds in order to stymie this Condition Z? To me, this is a defect or failure.

I guess you would argue that a clock that loses three minutes per day would not be a manufacturing defect or failure because it is still right twice a day.

 

[bhzmark]

few people have received on paper).
It WILL be up to the courts.
The Magnuson Moss Warranty Act is a great place to review what is and is not acceptable practice.

I got my own booklet that was in my glove box and was also in the pdf papers that were provided to me prior to the sale. I actually read them and emailed Jerome a correction to the owner's manual that had a typo. The warranty booklet I rec'd in 2014 has the exact same language currently on the pdf on Tesla's website.

many on here have argued that this mysterious Condition Z is a defect or failure.

Please cite the post?

 

[bhzmark]

Your cite is not on point. You are referencing a warranty claim against Honda regarding tires which have their separate warranty by the tire manufacturer, not Honda. Please find a cite that is clearly on point.

Read it again. The Honda limited warranty specifically limits the new car warranty to say that it doesn't cover something - here the tires. That they happen to have their own warranty isn't relevant to the court's stated reasoning that the specific warranty exclusion is enforced. But feel free to pretend that doesn't apply to you and you will receive your education that it does.

It isn't that hard to simply read the warranty and your tailor to argument to fit within it. Trying to say that warranty covers something that it specifically excludes is just stupid.

 

[DJRas]

World's best warranty
Creating the World’s Best Service and Warranty Program

I got my own booklet that was in my glove box and was also in the pdf papers that were provided to me prior to the sale. I actually read them and emailed Jerome a correction to the owner's manual that had a typo. The warranty booklet I rec'd in 2014 has the exact same language currently on the pdf on Tesla's website.



Please cite the post?

The current wording has changed. Most obviously today's warranty specifies the Model 3 70% degradation coverage.
So, you are being disingenuous that the wording is exactly the same.

Your last point. See post 1 reference to wk057's posts.

Edited to add link to warranty statement.

 

[Chaserr]

I think many on here have argued that this mysterious Condition Z is a defect or failure. If wk057 is to be believed, this was a serendipitous discovery by Tesla

Wk057 has said it is definitely a defect or failure and cannot be fixed without a battery replacement. He wasn't vague about that and it should be linked in post 1. He was vague about suggesting "i never said it wasn't a safety issue" when people were discussing reasons why nobody should update. He said that in conjunction with his disgust for the numerous terrible things v9 and newer bring on top of the downgrades, alluding to safety being more important than any inconvenience or financial hardship. If he was right, Tesla doesn't even get a choice to discuss warranty - it's a safety recall replacement instead.

 

[Guy V]

Your cite is not on point. You are referencing a warranty claim against Honda regarding tires which have their separate warranty by the tire manufacturer, not Honda. Please find a cite that is clearly on point. My guess that there are not any, and this is why Tesla is digging its heels in, and the plaintiff is forcing the issue.

I think many on here have argued that this mysterious Condition Z is a defect or failure. If wk057 is to be believed, this was a serendipitous discovery by Tesla as they were looking for Condition X. This Condition Z was deemed important enough to start the dominoes falling. Apparently, Tesla was unaware of the possibility of Condition Z from the start. Would Tesla have sold us these batteries from day one as originally configured had they known about Condition Z in 2011-2012? Or would Tesla have altered the chemistry, BMS, enlarged the packs, whatever to sell cars with stated range and Supercharger speeds in order to stymie this Condition Z? To me, this is a defect or failure.

I guess you would argue that a clock that loses three minutes per day would not be a manufacturing defect or failure because it is still right twice a day.

Actually, a clock that loses 3 minutes a day would only get the time right about once every eight months.

 

[raphy3]

It would be nice for people to actual provide specific citation and quotes.

We've already done that for you. It's here in the thread. The Tesla blog posts written by Elon Musk about the 85 battery and the Tesla blog posts written by Elon Musk about his interpretation of the warranty are both linked here. Just search the thread. Almost no legal defence will survive an attack against the wording in the warranty bolstered by the words of the company's own CEO, which will be taken plainly on their face as an advertisement to entice people to buy the car.

 

[Ferrycraigs]

A lot of this is very counterintuitive and it takes careful study to understand and why. I spent a lot of time in college chemistry understanding why cell voltage is only barely changed by electrolyte concentration for instance. It’s not exactly the same as the many modes of degradation in LiIon batteries, but it’s probably analogous. (I just felt the first thrown stone hit my head ) I always felt like the concentration of ions in the electrolyte should massively affect voltage, but it doesn’t. It only affects voltage measured across the terminals because the resistance of the electrolyte changes.

ultimately the voltage across the battery is determined by the electropotential difference of the anode and cathode. That potential is after all what gives the battery voltage (a measure of potential). At the end of the day, as long as the chemical composition of anode and cathode stay the same, the voltage across the battery will remain the same for a given state of charge. Only it’s ability to generate current will change as more or fewer (fewer in the case of degeneration) ions are able to participate in the exchange of electrons

If I may say so this is exactly why I attempted to provide my explanation.

You talk, very knowledgeably, about the voltage level across the battery and the many factors which affects it. I agree all your points. They are all spot on the money. And are correct. But I have no idea why you have made them. My post was simply trying to clarify the confusion between claims on one hand that the current perceived drop in capacity may be down to degradation, and the alternative view that such claims cannot be true as this drop in capacity is directly the result of a change in Vmax. And as there is NO form of degradation that alters Vmax, any degradation claim must fail. I hold the latter view. THE crux of my point is a change in Vmax can never be the result of degradation. That’s it. Nothing more, nothing less. The issue was not about how much charge a cell can hold, or what causes it to decrease. I only introduced that to show that type of cell voltage was not what I was talking about. If I did not make myself clear enough, and thereby caused confusion, that must fall at my door. I’m sorry if I caused confusion; based on your reply I appear to have.

Perhaps you don’t agree with the premise. That’s fine. To misquote Mr Rumsfeld, I hope I am wise enough to know what I don’t know. If you have an alternative theory on how degradation can alter Vmax I would, genuinely, be very interested to hear it.