Life and Death of Li Ion batteries

[TheDeuce]

Mikebentley said:

Quick question and please accept my apologies if it’s really daft. When charging a car or any device with a failing battery does the act of doing so cost more to do than it should. By this I mean does the act of trying to put more energy into a knackered cell actually mean that if the car only has 80% usable battery the effort of charging it cost more than the actual 80% figure. A bit like pouring petrol into a tank with a hole in it that will only fill to 80%.

Hope that makes sense.

The short answer is no, because the capacity has dropped by IE 10%, you can only put in 90% of the power used to be able to, so will only pay 90% of what you used to.

I'm by no means an expert but I know that as a battery starts to significantly degrade, charging does become less slightly less efficient - I don't know the % difference but I would guess in terms of dent on your wallet, probably not enough to notice the change over such a span of years.

The real cost of charging once a battery is heavily degraded, is that it will suffer damage at a greater rate each time it is charged. But a heavily degraded battery that has reached that stage is going to be in a very high mileage EV and has arguably done the job it was paid for to do, probably for at very least 200k miles. At that point, all cars are worn and less valuable - most are also very old and simply out of date in a fast moving world.

[anonymous-user]

TheDeuce said:

If what I am saying is correct that would suggest there should soon be a load of decade + old EV's with spaceship miles that still have very respectable 80%+ battery capacity - and there are. It's early days of course as we're only just starting to see significant numbers of decade+ cars, but so far the evidence is that the degradation simply isn't what was feared in the early days. We also know that charge cycles and use is the biggest contributor to degradation, so we can partly ignore the age of the car and just look at mileage - and again we see that heavy annual mileage cars with 200+ miles are also holding up just fine.

Incorrect.

https://www.recurrentauto.com/research/how-batteri...




Tesla battery looks knackered by 100k or they didn’t test it beyond that. Anyway, age is a factor.

Edited by anonymous-user on Tuesday 28th February 20:11

[OutInTheShed]

Evanivitch said:

OutInTheShed said:

LFP batteries are indeed good for many more cycles than most other chemistries.
But not many cars have LFP batteries.

Only about 20,000 standard range MG5/ZS, another 15,000 later Model 3 SR, and 20,000 Model Y sold on the UK!

Indeed.
About 6% of BEVs on UK roads?
It's possible in due course, the LFP cars will hammer the used value of cars with other chemistry.
I wasn't planning to wait that long though.

[TheDeuce]

paradigital said:

TheDeuce said:

It's completely different - you charge your iPhone every day, a typical driver in an EV will charge once per week = two years for your phone is 14 years for an EV.

You phone has zero battery management, it can't it has just one cell so it can't cycle cells discreetly. An EV has multiple cell clusters, when you 'fully charge', even to 100%, in reality it's kept a few back and it will keep track and make sure each cluster of cells in turn is cycled in the most efficient way possible in reaction to whatever the owners charging habits are.

Not just that but if you actually take care of your iPhone’s battery (not using it much below 20%, not regularly charging it above 80%) then you don’t wear it anywhere near as quickly.

My iPhone 13 Pro Max is still at 100% battery capacity and it’s now 16 months old, charged daily.

My Tesla on the other hand is also rarely charged above 80% (twice in 12 months) and again rarely discharged beyond 20% (once, the day I collected it with minimal range), has supposedly lost 3%, with the majority of that being the first few months, the degradation curve has flattened off since. It’s been supercharged 3 times, and is typically AC charged once a week.

The battery degradation curve is supposed to only increase over time and usage, not the other way around. I wonder if the measurement was pre-set to expect a certain number of values from a typical example of the battery and then adjusted itself to your car's specific battery over the first few months. I don't understand all the ins and outs but I know that battery capacity and health is something of an approximation.

[TheDeuce]

wormus said:

TheDeuce said:

If what I am saying is correct that would suggest there should soon be a load of decade + old EV's with spaceship miles that still have very respectable 80%+ battery capacity - and there are. It's early days of course as we're only just starting to see significant numbers of decade+ cars, but so far the evidence is that the degradation simply isn't what was feared in the early days. We also know that charge cycles and use is the biggest contributor to degradation, so we can partly ignore the age of the car and just look at mileage - and again we see that heavy annual mileage cars with 200+ miles are also holding up just fine.

Incorrect.

https://www.recurrentauto.com/research/how-batteri...




Tesla battery looks knackered by 100k or they didn’t test it beyond that. Anyway, age is a factor.

Edited by wormus on Tuesday 28th February 20:11

I said we can 'partly' ignore that factor, not that is wasn't a factor. I also said charging cycles were the 'biggest' factor. What part of that is incorrect?

[TheDeuce]

OutInTheShed said:

TheDeuce said:

It's completely different - you charge your iPhone every day, a typical driver in an EV will charge once per week = two years for your phone is 14 years for an EV.

Y....

Your phone may get charged more often, but a year is a year is a year.
Also although I charge my phone most nights, it's rarely discharged very deeply.
It does take a kicking when I run GPS based apps, which can flatten it in a day's hiking.
As it happens, my current phone is rather more than two years old.

A battery, or each cell, is a bit of wet chemistry. As well as wearing out from use, the 'wrong' chemical reactions happen over time.
That's pretty true for every flavour of battery, from Alkaline through lead acid to zinc carbon.
The LiFePO4 batteries which are favourite for home power storage are promising a lot more cycles than 'traditional' lithium, but feel free to point out any offering a decent warranty more than 10 years.

A year is only a year in relative terms if the car and phone go through the same number and % of capacity charge cycles as one another. Clearly that would be very unusual for the average person. Or are you suggesting that a car charged 30 times a year will last no longer than one charged daily, because a 'year is a year' ?

As for your phone charging routine, I strongly suspect you're well below average in terms of usage and the subsequent need to charge. I have mine plugged in all night and whenever I'm in the car, and even then I quite often need to plug in during the day. I use the phone solidly for hours each day, mostly streaming music or watching stuff on youtube as I work. I think it's reasonable to state that most people charge their smart phones at least daily and do notice some level of degradation around the two year mark - which is also typically when they upgrade to new handset.

[paradigital]

TheDeuce said:

The battery degradation curve is supposed to only increase over time and usage, not the other way around. I wonder if the measurement was pre-set to expect a certain number of values from a typical example of the battery and then adjusted itself to your car's specific battery over the first few months. I don't understand all the ins and outs but I know that battery capacity and health is something of an approximation.

These are figures from Tessie, and when comparing to the Tessie “fleet average” you see the same initial drop, followed by a flattening of the curve. So either all of Tessie’s data is wrong, or the cars do something odd for the first handful of charge cycles.

[TheDeuce]

paradigital said:

TheDeuce said:

The battery degradation curve is supposed to only increase over time and usage, not the other way around. I wonder if the measurement was pre-set to expect a certain number of values from a typical example of the battery and then adjusted itself to your car's specific battery over the first few months. I don't understand all the ins and outs but I know that battery capacity and health is something of an approximation.

These are figures from Tessie, and when comparing to the Tessie “fleet average” you see the same initial drop, followed by a flattening of the curve. So either all of Tessie’s data is wrong, or the cars do something odd for the first handful of charge cycles.

Probably the latter but who knows. I expect an expert will pick this up and explain that readings are taken over time which lead to a average reading with an ever decreasing margin of error blah blah and that the initial readings are fantasy. Probably a bit like range figures reported by the car. When mine arrived brand new it showed more or less the WLTP official range, over the next few hundred miles, needless to say, that came crashing back down to realistic levels.

[GT9]

wormus said:

Tesla battery looks knackered by 100k or they didn’t test it beyond that. Anyway, age is a factor.

In your opinion, what is the shape of the degradation curve for a typical Tesla battery, does the rate of degradation increase or decrease with time?

Second question, does your pre-conceived view prefer EV batteries to be as st as they can possibly be or as good as they can possibly be?

[anonymous-user]

TheDeuce said:

wormus said:

TheDeuce said:

If what I am saying is correct that would suggest there should soon be a load of decade + old EV's with spaceship miles that still have very respectable 80%+ battery capacity - and there are. It's early days of course as we're only just starting to see significant numbers of decade+ cars, but so far the evidence is that the degradation simply isn't what was feared in the early days. We also know that charge cycles and use is the biggest contributor to degradation, so we can partly ignore the age of the car and just look at mileage - and again we see that heavy annual mileage cars with 200+ miles are also holding up just fine.

Incorrect.

https://www.recurrentauto.com/research/how-batteri...




Tesla battery looks knackered by 100k or they didn’t test it beyond that. Anyway, age is a factor.

Edited by anonymous-user on Tuesday 28th February 20:11

I said we can 'partly' ignore that factor, not that is wasn't a factor. I also said charging cycles were the 'biggest' factor. What part of that is incorrect?

What does ‘partly’ ignore even mean? Are you saying you know calendar aging is a problem but you’re choosing to ignore it?


Here are some more facts:

“baseline degradation that every battery experiences is due to age and is called “calendar aging.” It doesn’t matter whether or not the battery is even used - it will degrade with time even while sitting on a shelf.”


https://www.recurrentauto.com/research/lessons-in-...

Some disappointing graphs to consider:

[anonymous-user]

GT9 said:

In your opinion, what is the shape of the degradation curve for a typical Tesla battery, does the rate of degradation increase or decrease with time?

Second question, does your pre-conceived view prefer EV batteries to be as st as they can possibly be or as good as they can possibly be?

Evidence provided above, quite a comprehensive article, free of bias, based on facts. I’ve not said EV batteries are st, they are simply constrained by the same physical properties as other batteries of their type, which is what I said in my first comment.

[SpeckledJim]

Standard Range Plus gets better with age?

That throws the whole thing into question.

[JonnyVTEC]

OutInTheShed said:

Indeed.
About 6% of BEVs on UK roads?
It's possible in due course, the LFP cars will hammer the used value of cars with other chemistry.
I wasn't planning to wait that long though.

You do know LFP is the non performance chemistry yeah?

[DMZ]

SpeckledJim said:

What do you think is being measured in order to come up with a random result?

It measures a battery capacity that fluctuates with temperature and maybe other environmental parameters. EVs lose 20-30% range in winter for a reason and you need to pre-condition for max charge.

If you read the details on any of this, to actually measure battery capacity requires a special process and special tooling.

I’ve checked these numbers on EVs that I have owned and they go up and down. There is no gentle slope with ever decreasing numbers. They’re generally low in winter and high in summer. I found them to be meaningless tbh and stopped looking at them.

But I would love to have actual facts around battery degradation. I’m not convinced that it is a problem in the real world when it comes to EVs for the reasons mentioned in the thread but it would be nice to know for sure.

[GT9]

wormus said:

GT9 said:

In your opinion, what is the shape of the degradation curve for a typical Tesla battery, does the rate of degradation increase or decrease with time?

Second question, does your pre-conceived view prefer EV batteries to be as st as they can possibly be or as good as they can possibly be?

Evidence provided above, quite a comprehensive article, free of bias, based on facts. I’ve not said EV batteries are st, they are simply constrained by the same physical properties as other batteries of their type, which is what I said in my first comment.

https://www.tesla.com/ns_videos/2021-tesla-impact-report.pdf

See page 67, I appreciate though that you may be suspicious of Tesla's own data.

Plenty of other nuggets of data in the impact report, what can you find that either concerns you or impresses you?

[OutInTheShed]

SpeckledJim said:

Standard Range Plus gets better with age?

That throws the whole thing into question.

I suspect it shows that simply reading the 'range' off the dash doesn't tell you the whole story.

Maybe higher mileage cars get driven in such a way that they do better mi/kWh?
Maybe the Muskware is compensating for the natural aging by allowing the battery to be flattened to a lower voltage?

[CoolHands]

DMZ said:

But I would love to have actual facts around battery degradation. I’m not convinced that it is a problem in the real world when it comes to EVs for the reasons mentioned in the thread but it would be nice to know for sure.

Of course it will be a problem as just like every other li ion battery everywhere, they will end up being useless. There is no magic involved. I actually think in some ways they could be worse than expected (hoped for) as every owner wants to always keep them at fully charged state (cos range anxiety), and fully charged batteries degrade worse than if they were, for example, mainly at storage voltage.

By the way, never watch a youtube video on sodium battery technology or you will be spammed to death with millions of bullstting videos about how they could be the next tech breakthrough for ev battery packs (they won’t).

[TheDeuce]

wormus said:

TheDeuce said:

wormus said:

TheDeuce said:

If what I am saying is correct that would suggest there should soon be a load of decade + old EV's with spaceship miles that still have very respectable 80%+ battery capacity - and there are. It's early days of course as we're only just starting to see significant numbers of decade+ cars, but so far the evidence is that the degradation simply isn't what was feared in the early days. We also know that charge cycles and use is the biggest contributor to degradation, so we can partly ignore the age of the car and just look at mileage - and again we see that heavy annual mileage cars with 200+ miles are also holding up just fine.

Incorrect.

https://www.recurrentauto.com/research/how-batteri...




Tesla battery looks knackered by 100k or they didn’t test it beyond that. Anyway, age is a factor.

Edited by wormus on Tuesday 28th February 20:11

I said we can 'partly' ignore that factor, not that is wasn't a factor. I also said charging cycles were the 'biggest' factor. What part of that is incorrect?

What does ‘partly’ ignore even mean? Are you saying you know calendar aging is a problem but you’re choosing to ignore it?


Here are some more facts:

“baseline degradation that every battery experiences is due to age and is called “calendar aging.” It doesn’t matter whether or not the battery is even used - it will degrade with time even while sitting on a shelf.”


https://www.recurrentauto.com/research/lessons-in-...

Some disappointing graphs to consider:

I don't know what your point/problem is. I commented on and accepted both calendar ageing and usage ageing. In terms of whether either or both will likely cause the battery to fail within the reasonable life of the car the only one that matter is most often going to be usage degradation. Hence, we can 'partly' ignore calendar ageing as it most cases it won't be the factor that dictates the battery making it to the end of the cars life - but I said 'partly' because I obviously do accept it is a factor in a very old car.

The car would have to be very old for calendar ageing alone bring the range down to impractical levels. The car would be older than most cars present lifespan. The thing that can make a far greater difference is heavy usage - which is why I gave examples of the earliest high mileage AND decade+ old cars that for the most part have not actually breached the 20% degredation threshold that is being discussed.

[TheDeuce]

CoolHands said:

DMZ said:

But I would love to have actual facts around battery degradation. I’m not convinced that it is a problem in the real world when it comes to EVs for the reasons mentioned in the thread but it would be nice to know for sure.

Of course it will be a problem as just like every other li ion battery everywhere, they will end up being useless. There is no magic involved. I actually think in some ways they could be worse than expected (hoped for) as every owner wants to always keep them at fully charged state (cos range anxiety), and fully charged batteries degrade worse than if they were, for example, mainly at storage voltage.

By the way, never watch a youtube video on sodium battery technology or you will be spammed to death with millions of bullstting videos about how they could be the next tech breakthrough for ev battery packs (they won’t).

You're literally making things up as you type. Not every owner keeps their EV's fully charged, myself and everyone else I know typically charges about once a week when the car is down to ~20%, or whatever works for them. It's obviously not going to be true that 'every' owner tries to keep their car fully charged I fear the range anxiety you refer to might be the range anxiety worried about by people that haven't actually lived with an EV and got over it.

Why will it 'of course' be a problem and the same as every other li-ion battery? The vast majority of li-ion batteries are a single cell and have no BMS to look after them, the most common li-ion batteries are charged every single day. An EV's battery is in a very different position. You can't say 'of course' it will be a problem because that was what was said when the first Tesla's were sold. Now, a decade later, it has not been a problem for hardly any of them, other than some known battery system faults which were addressed. Most of them are now very high milers, and have suffered far less degradation than expected - despite all the early cars having endless free DC charging and no doubt making great use of it - which is the most aggressive way to charge a battery, yet still... the batteries seem to have survived the decade of use and DC speed charging.

[CoolHands]

TheDeuce said:

You're literally making things up as you type. …,myself and everyone else I know typically charges about once a week when the car is down to ~20%,

Amazed you can write that first sentence followed by the second with a straight face. that is stretching credulity

Edited by CoolHands on Tuesday 28th February 21:48