Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health

[AAKEE]

I wanted to come back and report on my progress since I posted this.

Question is, should I go back to charging only to 50% to save on the calendar aging or keep charging up to 90% to keep the BMS current?

Well, all BMS calibrations is precisely what it is, a calibration of the BMS estimation of the battery capacity.

It does not increase the range of the car, it just increase the range number at the battery symbol. In a few cases, if the BMS was fairly off before, the navigation function can plan the trip more precise with a slightly larger range (but it seldom would mean traveling to a supercharger further away as they mostly are placed with longer intervals than the increased range.

So, I guess the fact above makes tge choice easier?
If seeing a high range number at the battery symbol is important long term = reduce the degradation by using the low SOC strategy.
(Charge as low as possible, as late as possible).

If seeing a high range today (and in very short term), continue to BMS calib.

For me, that always did use the low SOC strategy, but use high SOC when needed I can see a slight recovery in range by using low SOC after a period of supercharging sessions which often seem to lower the NFP slightly.

I would use the low SOC strategy if i where you and I would not care if the range dropped for some reason (knowing that low SOC reduces the degradation).

I actually had a big drop for some months last summer and I did not try to “up” it with any Bms calib or so.
(Actually I think I was responsible for the initial drop by doing some really low SOC cycles to make a reversed BMS calib.
The range came back by itself, eventually)

 

[citivolus]

Thanks all for your feedback--I agree that it makes sense to revert to a low SOC strategy. FWIW, it was really nice to only charge the car once a week. Hopefully in future generations of battery technology we can get the best of both worlds!

 

[citivolus]

The BMS is a bit like shopping around for the best blood pressure...it’s very reassuring when you get a low blood pressure and makes the high ones easy to forget...of course you are only fooling yourself. The BMS that reads the highest is of course the correct one....I mean it has to be, right
I also go with the logic of saving the battery by having a low state of charge (50%)....but this weekend I am going on a road trip to the beautiful town of Antibes....and I can’t wait to see what my range is with 100%

You're so lucky--Antibes is lovely! I remember visiting the Picasso museum there and feeling like the master could walk into the room at any moment.

 

[DownshiftDre]

Anybody willing to try the new “BMS Reset” function in Service Mode as part of 2023.12 update?

Any speculation on function and how it will perform it?

Wondering if it resets the CAC values that are driven by all past averaging and restarts algorithm from a fresh number. If so, it may mean calibration fluctuations for a while as it averages and settles out.

CAC=Calculated Amp-Hour Capacity

 

[Silicon Desert]

The BMS is a bit like shopping around for the best blood pressure...it’s very reassuring when you get a low blood pressure and makes the high ones easy to forget...of course you are only fooling yourself. The BMS that reads the highest is of course the correct one

Hmmm, as a person having worked on the first automated BP long ago, I am a little confused by that statement. The average over a period of time is the correct one.

 

[jim0266]

5. Low SOC is NOT dangerous. Below 20% is safe and do not cause increased wear. It actually reduce the calendar aging.
100% SOC is not as bad as the forum myth says. You do not need to drive asap.

I'll share my data and ask a question about the above quote.

Attached are the screenshots out of a spreadsheet I maintain on the ScanMyTesla data from my 2019 LR RWD Model 3. It just passed 4 years but only has 24,647 miles. I started tracking it around 6,000 miles when the Nominal Full Pack was reading 77.6 kWh and the Energy Buffer was at 3.50 kWh.

My stats have stayed flat since reaching around 13k miles about two years ago.

I follow all the good practices outlined by @AAKEE in the quoted text above since new. I generally stay between 70-30% SOC and lower on the high end when possible, even on road trips. During a 3,200 mile trip last fall these were the average SOC levels before after after supercharging:

• Avg SOC charging start: 37%
• Avg SOC charging end: 62%

My pack seems to be holding up quite well. It sits between 30-50% at home between charges.

In regard to the low SOC, that's something I've been wondering. If I'm better off, for example, charging to 80% and arriving at 30% or charging to 60% and arriving at 10%? It appears to be the latter. From something Jeff Dahn said I was avoiding going below 20-30% when possible.

Also, tracking my charging stats I've SuC 37% of the time and L2 charged 63% of the time due the roadtrips we've taken.

 

[eivissa]

MASTER THREAD: 2021 Model 3 - Charge data, battery discussion etc

Do we know if M3P uses the same battery with MYP (from Berlin) ? Yes. They both use the 5L 79 kWh LG battery.

teslamotorsclub.com

Panasonic 82kWh Degradation Survey

Degradation overview of the Panasonic "3L" 82kWh used in the Model 3 Performance Refresh 2021/2022 Akkuwiki @ TFF

forms.gle

Panasonic 82kWh Degradation Survey

Answers Zeitstempel,Build Location,Model Year,Delivery Quarter,Odometer,Rated Range,Battery Part Number,Battery Build Day,Battery Status,Battery Errors,Forum,Username 26.04.2023 09:18:07,LRW = Shanghai China,M = Refresh 2021,Q4/2021 - Oct to Dec 2021,14100,492,1800083-##-# Remanufactured,No, I d...

docs.google.com

 

[AAKEE]

My stats have stayed flat since reaching around 13k miles about two years ago.

I follow all the good practices outlined by @AAKEE in the quoted text above since new. I generally stay between 70-30% SOC and lower on the high end when possible, even on road trips. During a 3,200 mile trip last fall these were the average SOC levels before after after supercharging:

• Avg SOC charging start: 37%
• Avg SOC charging end: 62%

My pack seems to be holding up quite well. It sits between 30-50% at home between charges.

Yes, the time above 55% (displayed SOC) is what to reduce to reduce calendar aging.

In regard to the low SOC, that's something I've been wondering. If I'm better off, for example, charging to 80% and arriving at 30% or charging to 60% and arriving at 10%? It appears to be the latter. From something Jeff Dahn said I was avoiding going below 20-30% when possible.

I have only seen one video a couple of years ago from Jeff Dahn.

If Jeff Dahn tell us to avoid going below 20-30% SOC, something is fishy. Very fishy actually.

There are some (not very big) differences between chemistries but generalky speaking all the chemistries used for EV’s is happy at low SOC.
Calendar aging is the biggest degrador initially and will be that for five-eight years, or so.
We have yet to see a research report showing that below 20-30 isnt good.

This is cycling at different SOC, not Panasonic cells but anyway:

Pictures above it not the only sources for stating this, its the sum from reading hundreds of research reports.

In general, the lower the SOC, the lower the calendar and cyclic aging.
-Charge as late as possible
-Charge as little as needed (include a margin for range anxiety).
-Charge often

So, 60-10% should be better than 80-30%.

 

[DownshiftDre]

I have only seen one video a couple of years ago from Jeff Dahn.

If Jeff Dahn tell us to avoid going below 20-30% SOC, something is fishy. Very fishy actually.

Any speculation what he is trying to say? It is fishy and the data doesnt back it up. I almost spit out my coffee when I watched it. My M3P will sometimes sit <20% for days and for when I am on travel. Got a little concerned but saw your post right after with your data Ive seen 100s of times and I think I feel better again lol.

 

[KenC]

I'll share my data and ask a question about the above quote.

Attached are the screenshots out of a spreadsheet I maintain on the ScanMyTesla data from my 2019 LR RWD Model 3. It just passed 4 years but only has 24,647 miles. I started tracking it around 6,000 miles when the Nominal Full Pack was reading 77.6 kWh and the Energy Buffer was at 3.50 kWh.

My stats have stayed flat since reaching around 13k miles about two years ago.

I follow all the good practices outlined by @AAKEE in the quoted text above since new. I generally stay between 70-30% SOC and lower on the high end when possible, even on road trips. During a 3,200 mile trip last fall these were the average SOC levels before after after supercharging:

• Avg SOC charging start: 37%
• Avg SOC charging end: 62%

My pack seems to be holding up quite well. It sits between 30-50% at home between charges.

In regard to the low SOC, that's something I've been wondering. If I'm better off, for example, charging to 80% and arriving at 30% or charging to 60% and arriving at 10%? It appears to be the latter. From something Jeff Dahn said I was avoiding going below 20-30% when possible.

Also, tracking my charging stats I've SuC 37% of the time and L2 charged 63% of the time due the roadtrips we've taken.

Thanks for the data. I was wondering about the NFP variation showing in my SMT data. It's been varying between 75.3 and 76.4, so it's good to see yours varies about the same amount.

 

[AAKEE]

Any speculation what he is trying to say? It is fishy and the data doesnt back it up. I almost spit out my coffee when I watched it. My M3P will sometimes sit <20% for days and for when I am on travel. Got a little concerned but saw your post right after with your data Ive seen 100s of times and I think I feel better again lol.

I might look into he's statements later just to make another judgement. From what I remember from the video I saw, I wasnt completely impressed as all statements was not in line with the research. I will rather follow 100 reserchers where I can read and judge the test data then a single battery doctor. (Not saying anything is wrong but I will need to check it up before saying either thumbs up or down.

For the sum of the research it is solid enough to be able to say that low SOC is safe.

There are some research reports that find that the lowest degradation in the cycles *specific for NCA tests* is not at very low SOC, ansd thad cycles at very low SOC increase the cyclic aging slightly.
On the other hand there is no reports that doesnt find that 0% SOC gives the lowest calendar aging. As calendar aging takes the biggest bite of the battery during the first 5 years or more, I would prioritize low calendar aging if I had to. leading to *As low SOC as possible*

 

[johnny_cakes]

In regard to the low SOC, that's something I've been wondering. If I'm better off, for example, charging to 80% and arriving at 30% or charging to 60% and arriving at 10%? It appears to be the latter. From something Jeff Dahn said I was avoiding going below 20-30% when possible.

Jeff Dahn says in the video: "the main degradation modes happen at the top charge and bottom discharge of the chemistry that are used". It would be interesting to hear his rationale for not going below 30% SoC routinely, as he seems to be a respected expert on Li-on batteries.

 

[johnny_cakes]

I might look into he's statements later just to make another judgement.

It would be interesting to see what you find

 

[AAKEE]

Jeff Dahn says in the video: "the main degradation modes happen at the top charge and bottom discharge of the chemistry that are used". It would be interesting to hear his rationale for not going below 30% SoC routinely, as he seems to be a respected expert on Li-on batteries.

If we are talking about calendar aging, this is lower the lower the SOC is, down to 0% (0% is not completely empty but the low end of the approved discharge cycle, 2.5V /cell is the standard for NCA and NMC.

Overdischarge can cause damage but the research on this subject does not find any damage if the overdischarge is below about 50% of the voltage (down to about 1.5V or so). A Complete discharge to 0V is not good, but as the Bms shut down the battery at or above 2.5V/cell this wont happen to us, unless we leave the car below 0% for extrnded periods.
(There is some posts by me here on TMC about overdischarge, with references and pictures)
(There also is a recent case here on TMC with a model 3 left at the workshop with 0% for seven weeks, and latest info is that the battery is fine.)

If Jeff Dahn refers to cyclic aging heres tre different cycling tests on Panasonic NCA:

4.2V = 100%
4.1V = about 90%
4.0V = about 80%

All these tests was Discharged to the 2.5V discharged limit (this means until a Tesla stops, about 4.5% below 0% displayed).

100-0% gives about 625-650 cycles. Thats 260.000 km until loosing 20%. Assuming 400km range on a LR if driven from 100% until it stops.

90-0% gives about 800 Full Cycle Equivalents, so 320.000km

80-0% gives about 1000 FCE, so about 400.000km

Can we see a pattern of cycles down to 0% not killing the battery? (Yes, we can).

In the Tesla 30% degradation we probably could add some cycles before we reach the degradation for warranty. So low SOC is not that bad, I’d say.

 

[johnny_cakes]

If we are talking about calendar aging, this is lower the lower the SOC is, down to 0% (0% is not completely empty but the low end of the approved discharge cycle, 2.5V /cell is the standard for NCA and NMC.

Overdischarge can cause damage but the research on this subject does not find any damage if the overdischarge is below about 50% of the voltage (down to about 1.5V or so). A Complete discharge to 0V is not good, but as the Bms shut down the battery at or above 2.5V/cell this wont happen to us, unless we leave the car below 0% for extrnded periods.
(There is some posts by me here on TMC about overdischarge, with references and pictures)
(There also is a recent case here on TMC with a model 3 left at the workshop with 0% for seven weeks, and latest info is that the battery is fine.)

If Jeff Dahn refers to cyclic aging heres tre different cycling tests on Panasonic NCA:

View attachment 932072
4.2V = 100%
4.1V = about 90%
4.0V = about 80%

All these tests was Discharged to the 2.5V discharged limit (this means until a Tesla stops, about 4.5% below 0% displayed).

100-0% gives about 625-650 cycles. Thats 260.000 km until loosing 20%. Assuming 400km range on a LR if driven from 100% until it stops.

90-0% gives about 800 Full Cycle Equivalents, so 320.000km

80-0% gives about 1000 FCE, so about 400.000km

Can we see a pattern of cycles down to 0% not killing the battery? (Yes, we can).

In the Tesla 30% degradation we probably could add some cycles before we reach the degradation for warranty. So low SOC is not that bad, I’d say.

Very convincing, and I'm definitely a subscriber of your lower SoC for longer the better theory (even down to 0%). But I'm still curious why Jeff Dahn would advocate against going below 30% SoC. If it's for range anxiety, that's a reasonable argument, but he implied that it was for battery degradation. So that's my confusion. If it was any random person, I wouldn't think much of it, but Jeff Dahn's been researching Li-ion batteries for decades and has even consulted for Tesla, so I'm still interested in understanding his rationale for making such statement.

 

[AAKEE]

Thanks for the data. I was wondering about the NFP variation showing in my SMT data. It's been varying between 75.3 and 76.4, so it's good to see yours varies about the same amount.

I often have vary stable NFP when using 55% SOC target for extended time. Sometimes same on the point during three-four weeks.
Charging higher several times for longer trips can change it up or down slightly, and when going back to 55% it stabilizes, back on the former number.

 

[Hiline]

60.000km / 2 years 3 months update:

78.8 kWh capacity / 495-496* km range left (out of 507 km).

View attachment 923178

The Low SOC strategy works fine!

*Theres a bug in Scan my Tesla so full rated range is dependant on the SOC, at hogh SOC 495-496 is shown, and when SOC decreases, that full rated rabge decreases.

2% degradation in the first 2 years is the best I've ever seen. Your method definitely seems to be working!

 

[AAKEE]

Very convincing, and I'm definitely a subscriber of your lower SoC for longer the better theory (even down to 0%). But I'm still curious why Jeff Dahn would advocate against going below 30% SoC. If it's for range anxiety, that's a reasonable argument, but he implied that it was for battery degradation. So that's my confusion. If it was any random person, I wouldn't think much of it, but Jeff Dahn's been researching Li-ion batteries for decades and has even consulted for Tesla, so I'm still interested in understanding his rationale for making such statement.

I just watched a presentation from Jeff Dahn (

)

He did not say anything strange.
He showed the work on lithium batteries that could do very many cycles.
All was tested down to 3.0V (which was considered 0% on those cells). He is impressed himeself.

 

[DownshiftDre]

Thanks @AAKEE I always wondered with all this data if calendar aging and cycling aging are exclusive from one another.

Meaning when my car is sleeping in the garage am I only getting calendar aging?

Or another case would be if I am supercharging and flowing energy in to a hot battery and subsequent drive after, am I only getting cycling aging at the elevated battery temperature? Or does time at temp still apply here as a double whammy.

Another case would be if I have my car in garage and sentry mode on, car is pulling some load, am I only getting cyclic aging?

Seems its a blended aging effect but wonder if there is even further best practices I can do to reduce any aging further even beyond lowered SoC, especially where I live in the hot summers. The data research always run tests on calendar aging or cyclic aging but not together and its impact, if any.

 

[Candleflame]

Thanks @AAKEE I always wondered with all this data if calendar aging and cycling aging are exclusive from one another.

Meaning when my car is sleeping in the garage am I only getting calendar aging?

Or another case would be if I am supercharging and flowing energy in to a hot battery and subsequent drive after, am I only getting cycling aging at the elevated battery temperature? Or does time at temp still apply here as a double whammy.

Another case would be if I have my car in garage and sentry mode on, car is pulling some load, am I only getting cyclic aging?

Seems its a blended aging effect but wonder if there is even further best practices I can do to reduce any aging further even beyond lowered SoC, especially where I live in the hot summers. The data research always run tests on calendar aging or cyclic aging but not together and its impact, if any.

a cycle is a cycle. if you arent using your car you arent cycling it.
the temperature will accelerate aging but also protect the battery at higher loads....

i think you are overthinkign this. the reason calender aging is more important than cycling is because most people dont drive enough kms for cycling to matter all that much.