Is battery calibration pointless?!

[shahryaran]

Let's say your car has some amount of battery degradation and you can't get the range you want.
You were told to calibrate battery and you may get some range back.

Here is the thing...
It doesn't matter and don't worry about it.
The fact is that the actual amount of battery capacity is there (minus the battery degradation) regardless of what the car shows as estimated range. Either the top end reading is incorrect or the button end reading. Your car will still drive even if it's at 0% (not recommended) just because the reading is incorrect, it doesn't mean that the actual battery capacity is not there.

In my opinion, battery calibration is kind of useless because:

1. It doesn't effect your actual range

2. You can't show it as evidence to claim it for replacement under warranty because it is not enough lose.

3. Charge from 5% to 100% (or whatever you way of calibration is) and repeating it only further wears out the battery.

4. Even after a successful calibration, the gain in displayed range is not much and it wouldn't made a difference anyway because the displayed range is an estimate after all.

There is no need to worry about if you can get the car to show you 15 or 20 or 30 miles on the display. It's the same battery whether it shows 20 miles more or less. That's why there are a lot of super chargers around.

The BMS knows how to balance the cells and get the best energy out of them.

Just drive your car, enjoy it and take good care of it.
Don't let it go down to 0% and don't keep it at 100%. That's it.

 

[AAKEE]

Let's say your car has some amount of battery degradation and you can't get the range you want.
You were told to calibrate battery and you may get some range back.

There is no such thing as ”calibrating the battery”.
What can be done is helping the BMS to see the battery capacity. This is often called a ”BMS calibration”.

This will not give you any true range back.
The car might show more range by the battery symbol but there is no change to the real actual range.
If the BMS is very off, a BMS calibration might make the navigatation range prediction a little better.

Your car will still drive even if it's at 0% (not recommended) just because the reading is incorrect, it doesn't mean that the actual battery capacity is not there.

0% displayed means about 4.5% of the total capacity still left below 0% displayed so the car can be driven past 0% even when the Bms is not wrong.

Going to 0% is not dangerous, but it is vice to charge soon after reaching 0% or close to 0%.

Don't let it go down to 0% and don't keep it at 100%. That's it.

Going down to 0% is not bad.

Its not that bad to keep it at 100% either.

Both these are forum myths.

 

[shahryaran]

Going down to 0% is not bad.

Its not that bad to keep it at 100% either.

Both these are forum myths.

The electrolyte membrane between cathode and anode gets thiker at 0% and 100%. This phenomena also knows a battery degradation.

 

[ATPMSD]

Unless you are a person who likes to push range to the limits, don't worry about it. Just follow what you said earlier:

Don't let it go down to 0% and don't keep it at 100%. That's it.

 

[AAKEE]

The electrolyte membrane between cathode and anode gets thiker at 0% and 100%. This phenomena also knows a battery degradation.

You seem to have more or less all research on this against you.

This is what all researchers find:


In this case, actual model S cells tested.

The best SOC to reduce calendar aging is 0% (the cells are not completely empty at 0%, 0% is the ”stop discharge point” set by the battery manufacturer.
In this case, 2.5V/cell but Teslas 0% displayed is 4.5% true SOC so we are very safe at 0% displayed.

100% has about the same degradation rate as at 70-90%, unless in extreme heat where the degradation rate is slightly worse at 100% than at 70-90%.

In some cases the tests even show the worst degradation rate at 80% for the Panasonic cells Tesla use. (As seen in the second picture above).

The 0% and 100% being bad is forum myths.
If ypu do not believe me, its time to start searching the net for facts about this mather
(Hints: degradation from time is called calendar aging, so thats a good term to use. Degradation from charging/driving is called cyclic aging).

 

[BobX]

I havae a 2017 X 75D. I followed the BMS calibration instructions in this article-- Tesla battery management system (BMS) calibration .
I let the car sit overnight unplugged at 10% charge. The next morning I set the charge limit to 100% and started charging. The charging stopped at 93%. Drove the car for a couple of weeks and repeated the process. This time the car charged to 100%. The range estimate on the dash was 50 kilometers higher than the 375 kilometer Tesla range. I understand, however, that this is an estimate. I drive to my son's home regularly. In the past I would arrive with about 50% battery left. After the BMS calibration, I had 61% left. Conclusion: there seems to be some merti (at least in my case) that BMS calibration is helpful.

 

[shahryaran]

You seem to have more or less all research on this against you.

This is what all researchers find:
View attachment 981085

In this case, actual model S cells tested.
View attachment 981086

The best SOC to reduce calendar aging is 0% (the cells are not completely empty at 0%, 0% is the ”stop discharge point” set by the battery manufacturer.
In this case, 2.5V/cell but Teslas 0% displayed is 4.5% true SOC so we are very safe at 0% displayed.

100% has about the same degradation rate as at 70-90%, unless in extreme heat where the degradation rate is slightly worse at 100% than at 70-90%.

In some cases the tests even show the worst degradation rate at 80% for the Panasonic cells Tesla use. (As seen in the second picture above).

The 0% and 100% being bad is forum myths.
If ypu do not believe me, its time to start searching the net for facts about this mather
(Hints: degradation from time is called calendar aging, so thats a good term to use. Degradation from charging/driving is called cyclic aging).

Lithium ion battery degradation: what you need to know

The expansion of lithium-ion batteries from consumer electronics to larger-scale transport and energy storage applications has made understanding the many mechanisms responsible for battery degradation increasingly important. The literature in this complex topic has grown considerably; this...

pubs.rsc.org

 

[shahryaran]

You seem to have more or less all research on this against you.

This is what all researchers find:
View attachment 981085

In this case, actual model S cells tested.
View attachment 981086

The best SOC to reduce calendar aging is 0% (the cells are not completely empty at 0%, 0% is the ”stop discharge point” set by the battery manufacturer.
In this case, 2.5V/cell but Teslas 0% displayed is 4.5% true SOC so we are very safe at 0% displayed.

100% has about the same degradation rate as at 70-90%, unless in extreme heat where the degradation rate is slightly worse at 100% than at 70-90%.

In some cases the tests even show the worst degradation rate at 80% for the Panasonic cells Tesla use. (As seen in the second picture above).

The 0% and 100% being bad is forum myths.
If ypu do not believe me, its time to start searching the net for facts about this mather
(Hints: degradation from time is called calendar aging, so thats a good term to use. Degradation from charging/driving is called cyclic aging).

Looks like you are taking about storing battery. In that case, 50% is the best state of storage because there is very little energy (electrons) transfer between anode and cathode.

 

[Darmie]

Looks like you are taking about storing battery. In that case, 50% is the best state of storage because there is very little energy (electrons) transfer between anode and cathode.

If I read the charts correctly, 20% appears to be the best state of charge for storage to limit calendar aging degradation.

 

[shahryaran]

You seem to have more or less all research on this against you.

This is what all researchers find:
View attachment 981085

In this case, actual model S cells tested.
View attachment 981086

The best SOC to reduce calendar aging is 0% (the cells are not completely empty at 0%, 0% is the ”stop discharge point” set by the battery manufacturer.
In this case, 2.5V/cell but Teslas 0% displayed is 4.5% true SOC so we are very safe at 0% displayed.

100% has about the same degradation rate as at 70-90%, unless in extreme heat where the degradation rate is slightly worse at 100% than at 70-90%.

In some cases the tests even show the worst degradation rate at 80% for the Panasonic cells Tesla use. (As seen in the second picture above).

The 0% and 100% being bad is forum myths.
If ypu do not believe me, its time to start searching the net for facts about this mather
(Hints: degradation from time is called calendar aging, so thats a good term to use. Degradation from charging/driving is called cyclic aging).

If its just a myth, Tesla wouldn't recommend not going down to 0%or keeping it at 100%

 

[AAKEE]

If its just a myth, Tesla wouldn't recommend not going down to 0%or keeping it at 100%

You need to show me where Tesla say that we should not leave it at 100% or not go down to 0%.

 

[AAKEE]

Lithium ion battery degradation: what you need to know

The expansion of lithium-ion batteries from consumer electronics to larger-scale transport and energy storage applications has made understanding the many mechanisms responsible for battery degradation increasingly important. The literature in this complex topic has grown considerably; this...

pubs.rsc.org

You need to do your homework better.
That report refers to some reports we can not access that easy.
All research on for example Panasonic NCA like model s /x and model 3/y in USA that calendar aging is lower the lower the SOC is.

Calendar aging will cause much more degradation than cyclic aging for the most owners.
Calendar aging will be in the ball park of 5% the first year, 10% after four years and 14% after eight years.
Cyclic aging will be around 0.5-1% annually for the average owner.
The cyclic aging will be as high as the calendar aging until after 6-8 years, when the calendar aging has reduced the pace enough.

 

[AAKEE]

Looks like you are taking about storing battery. In that case, 50% is the best state of storage because there is very little energy (electrons) transfer between anode and cathode.

No.

Calendar aging happens all the time, and the battery do not know if it is stored or just sitting in the garage, so it does the same thing anyway -> calendar aging.

The lower the SOC, the lower the calendar aging.
The lower the temperature, the lower the calendar aging.
Tesla recommends storing all batteries that is not in cars between 15-50% SOC.


This is one example of Panasonic NCA calendar aging.

This is another one, alsoPanasonic NCA cells

This is actual Tesla model S cells taken from a car and tested.

This is actual Tesla model 3 cells (Panasonic 2170)

If we look at the cyclic aging, here from Tesla model S cells, that was run from 100-0%, they lost about 12.5% after 500 cycles.
Still cycled 100-0%, and at quite high current rates:
12.5% after 500 FCE cycles. 500 FCE cycles is about 200.000km and the sverage owner might drive 1/10 of this annually. So the annual cyclic aging will be about 1.25%, dedpite doing 100% charging and running down to true 0% each time.
Most owners do not drive like that.

To reduce degradation we should in the first place try to reduce the average SOC.
Charging late to reduce the time at high SOC.
Also, stay at low SOC. Do not charge more than needed, so 50% is a good charging level if you do not need more than that.
Charhe often, to reduce the cycles.

 

[shahryaran]

I don't know. All this looks like it is about storing.

My point was that calibrating is not something the consumer should be worry about.

 

[AAKEE]

I recommend reading this research report:
https://mediatum.ub.tum.de/doc/1355829/file.pdf

And this:
ShieldSquare Captcha

This might be a good read (actual model 3 cells), even if they had much higher charging and discharging rate than we have regularly in hour cars:
http://kth.diva-portal.org/smash/get/diva2:1755178/FULLTEXT01.pdf

Tesla model 3 cells:
https://research.chalmers.se/publication/535926/file/535926_Fulltext.pdf

Tesla model S cells, calendar and cyclic aging:
ShieldSquare Captcha

And this:
https://www.researchgate.net/profil...-side-reactions.pdf?origin=publication_detail

From the first report above, se have cyclic aging on Panasonic NCA cells:
They last about 750 FCE when cycled from 100-0%
750 FCE would be about 300K km
They last about 1000 FCE when cycled about 90% to 0% (400K km) and they last more than 1000 FCE when cycled 80-0%.

If 100% and 0% was very bad, they would not last for 750FCE and 300.000km or 200.000 miles.

 

[father_of_6]

I havae a 2017 X 75D. I followed the BMS calibration instructions in this article-- Tesla battery management system (BMS) calibration .
I let the car sit overnight unplugged at 10% charge. The next morning I set the charge limit to 100% and started charging. The charging stopped at 93%. Drove the car for a couple of weeks and repeated the process. This time the car charged to 100%. The range estimate on the dash was 50 kilometers higher than the 375 kilometer Tesla range. I understand, however, that this is an estimate. I drive to my son's home regularly. In the past I would arrive with about 50% battery left. After the BMS calibration, I had 61% left. Conclusion: there seems to be some merti (at least in my case) that BMS calibration is helpful.

While this is true, what's being stated in this thread is that the BMS calibration didn't actually change anything regarding the physics of your battery... just in the range displayed by the BMS.

That *does* have a real-world impact though, as the navigation and driver both make charging decisions based on the displayed range.

I'm not so confident about that stated claim of this thread, really. Please someone chime in and correct me if I'm wrong.

1. It doesn't effect your actual range

If the BMS believes that your battery is at 100%, it will stop charging (assume you've set it to 100%)... right?

If the BMS is incorrect because of an imbalanced cell at the top (one that has hit its max capacity before all of it's neighbors), all of the non imbalanced cells will *not* be able to charge to their full capacity.

When that happens and the BMS can detect it, the imbalanced cell is bled of its excess energy so that it is online with it's neighboring cells. After that imbalance is corrected, all of the cells are now able to charge to their full capacity.

I'm not an EE, just a forum layman and explaining it the way I understand it. I watched a really good YouTube video here on the forums somewhere explaining it... can't find it now though.

 

[shahryaran]

I recommend reading this research report:
https://mediatum.ub.tum.de/doc/1355829/file.pdf

And this:
ShieldSquare Captcha

This might be a good read (actual model 3 cells), even if they had much higher charging and discharging rate than we have regularly in hour cars:
http://kth.diva-portal.org/smash/get/diva2:1755178/FULLTEXT01.pdf

Tesla model 3 cells:
https://research.chalmers.se/publication/535926/file/535926_Fulltext.pdf

Tesla model S cells, calendar and cyclic aging:
ShieldSquare Captcha

And this:
https://www.researchgate.net/profil...-side-reactions.pdf?origin=publication_detail

From the first report above, se have cyclic aging on Panasonic NCA cells:
They last about 750 FCE when cycled from 100-0%
750 FCE would be about 300K km
They last about 1000 FCE when cycled about 90% to 0% (400K km) and they last more than 1000 FCE when cycled 80-0%.
View attachment 981215

If 100% and 0% was very bad, they would not last for 750FCE and 300.000km or 200.000 miles.

These are long. It's gonna take a while for me to get back to you.
But in general, wouldn't you agree that keeping a battery half full most of the time results in longer lifetime? For example, hypothetically, charging from 40%-60% everyday in compare to 10%-90% ?

 

[shahryaran]

I recommend reading this research report:
https://mediatum.ub.tum.de/doc/1355829/file.pdf

And this:
ShieldSquare Captcha

This might be a good read (actual model 3 cells), even if they had much higher charging and discharging rate than we have regularly in hour cars:
http://kth.diva-portal.org/smash/get/diva2:1755178/FULLTEXT01.pdf

Tesla model 3 cells:
https://research.chalmers.se/publication/535926/file/535926_Fulltext.pdf

Tesla model S cells, calendar and cyclic aging:
ShieldSquare Captcha

And this:
https://www.researchgate.net/profil...-side-reactions.pdf?origin=publication_detail

From the first report above, se have cyclic aging on Panasonic NCA cells:
They last about 750 FCE when cycled from 100-0%
750 FCE would be about 300K km
They last about 1000 FCE when cycled about 90% to 0% (400K km) and they last more than 1000 FCE when cycled 80-0%.
View attachment 981215

If 100% and 0% was very bad, they would not last for 750FCE and 300.000km or 200.000 miles.

Was test on individual cell? Or complete lack with Tesla BMS?

 

[AAKEE]

If you think a little about these lithium batteries, they have their maximum charge voltage and end of discharge voltage set so they do not break from regular use.
The manufacturers set the limits so the batteries can handle it, of course.

Buy any lithium batteries, like these, very close to model S cells.

Then read the specification:
Pansonic 18650B spec

There is no wording on not to leave them at 100%!
For very many applications, we really do not have any choice but to charge to full and then have them there for weeks, or months.
They do not break from this. They degrade slightly faster at high SOC than at low SOC, but above 55-60% to 100% there is not a very big difference.

I actually made that (already having very many lithium batteries singe long time and chargers), I bought 35 pieces of Panasonic NCR2170 , Tesla model 3 cells. These are from two different batches, 25+10.
I cycled all five times, and measured the capacity afyer that.
I did after that set them to 0, 20, 50, 80 and 100% and this was with the voltages according to Teslas displayed SOC, not trie SOC.

The 0% ones degraded least after one year.
(All cells was cycled/checked each two months).
20 and 50% was second best and quite close, a little more than the 0% cells.
80% was worst, about 15-20% more degradation than the 100% cells.

I used four at each SOC, teo from each batch. I also selected one better and one ”worse” of each type at each SOC, so I did not use the ones with best capacity at 100%.

Initially I planned to make my own graph of the results, but it was a very close match to the most common graphs I post so really no need for that.

This graph and my results are a very close match:

This is the five month graph, there also is a 18 month graph if I remember it correct.
Anyway, its a close match and the square root of time behaviour is confirmed.

I had a friend asking for some cells, he did get cells from me which included the cells that was at 100% for one year. They still work fine.

 

[AAKEE]

These are long. It's gonna take a while for me to get back to you.
But in general, wouldn't you agree that keeping a battery half full most of the time results in longer lifetime? For example, hypothetically, charging from 40%-60% everyday in compare to 10%-90% ?

Smaller cycles are better, thats no wuestion sbout it.

Low SOC is proved to be better.

I did run my M3P with the low SOC stategy for the 2.5 Years I had it.
Charged to 55% daily (as 55% gives the same calendar aging as the lowest charge setting, 50%).
I did charge late, thats so the car was just ready for the drive the next day.
Most often the car ended ip with 20-30% in the end of the day.
After I changed job, I have a long drive so I arrive with 10-15% and leave it like that for the week at work. I charge just before driving home.

My car had the lowest, or was among the cars with the lowest degradation in the Teslafi battery report for the same tesla.
I still had 492km range, out of 507km when I did the last full charge, and the average teslafi M3P with the same miles (66000km) had 463-465km.
My car often stood with low SOC, and I was down to 0% several times, and to -2% twice.