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

[AAKEE]

It seems clear that if you're in the 20-50% range of SOCs (where you'll be if your daily charge level is 50%) you'll probably do better than being in the 60-90% range of SOCs. A lot better? Maybe not. Is there possibly a large element of luck? I still think that's quite possible.

However, it definitely seems like warmer environments are worse, which isn't really a surprise.

Keeping the SOC low as we say, below the about 57% step will basically cut the degradation in half. That should be quite safe to say.

The abolute main part of the people that see issues with higher degradation than they had expected use high SOC, leave the
car charged for time and also mostly live where the temperature have an negative effect.
There is a very few that use high SOC in warmer climate that see very low degradation.
Do we
Know anyone that use low SOC and have lost a lot?

As the research( a lot of research) show very consistent results, its very hard to see
that the same or very closely related cells should behave different mounted in a car.

 

[Steve446]

Keeping the SOC low as we say, below the about 57% step will basically cut the degradation in half. That should be quite safe to say.

The abolute main part of the people that see issues with higher degradation than they had expected use high SOC, leave the
car charged for time and also mostly live where the temperature have an negative effect.
There is a very few that use high SOC in warmer climate that see very low degradation.
Do we
Know anyone that use low SOC and have lost a lot?

As the research( a lot of research) show very consistent results, its very hard to see
that the same or very closely related cells should behave different mounted in a car.

Totally agree with you. This assumes that the procurement and assembly process and inventory management is under control.

 

[AlanSubie4Life]

the production nowadays is so vast they are probably all identical

Every manufacturing process has a random variation in the output. It's fundamental. The only question is what the standard deviation is. It may be quite tight. Also, if it's truly random and there's no mean shifts over time, you'd expect it to be very tight at a pack level composed of 4416 cells.

Do we
Know anyone that use low SOC and have lost a lot?

I'm not aware of anyone, but of course most people use about 70-80% per recommendations, so I think it would be hard to get a good sample of (crazy? ) people who use 50% for their charge limit.

I've definitely come more to your view that the driving factor here is calendar aging in the results people see, and you've well documented that SOC is crucial. So I think that you're right that the best strategy is to use as low an SOC as practicable for the use case.

However, it's still a mystery to me exactly how much variability we might see (or even fundamental differences in initial capacity due to design tweaks) in these cells. The degradation threshold in 2018/2019 vehicles was 76kWh. Not 77.8kWh like in new vehicles. Why was that? Were all the cells slightly less dense initially (they still had 77.8kWh "FPWN" nominal value in 2018/2019 vehicles)? Did they tweak the capacity of these cells very slightly over time? We just don't know.

I don't think we're seeing day-to-day variation of more than 1% or so for new packs. But over time, has the mean shifted a little, due to small iterations in the cell design? I don't know. I don't think it's realistic to think that the cell design was not changed at all over time as learning and cost reduction measures were rolled in.

To be clear, I don't think there's any way to answer these questions, nor is there anything an end user can do about these factors, so it's best just to follow your strategy of using the lowest SOC possible which is convenient for the user, if minimal calendar aging is desired.

 

[Candleflame]

As you say, the fact that people are mentioning differences in different batches of batteries suggest that 1) either the variability is inherent in the design and physical manufacturing process and functioning of the batteries, or 2) the battery raw materials selection and manufacturing and assembly process is not fully under control or, 3), both 1) and 2). It's hard to say for sure because there are a fair few different experiences and opinions and operating conditions with different extremes eg N Sweden and Queensland as examples. I'm uncertain that this is luck. These are physical-chemical properties that are, in principle, capable of optimized consistency within stated operating parameters. In the pharma industry (of which I'm part) we call this optimized design space. it's unknown to me whether this is the case of the batteries in EVs. I would be surprised if these manufacturing conditions were not well known

Few ppl in cairns (like miami) have horrendous degradation, but the other guy here from townsville (again like miami) has relatively little despite charging to 80%. Battery lottery is definetly a thing.

 

[Candleflame]

Every manufacturing process has a random variation in the output. It's fundamental. The only question is what the standard deviation is. It may be quite tight. Also, if it's truly random and there's no mean shifts over time, you'd expect it to be very tight at a pack level composed of 4416 cells.



I'm not aware of anyone, but of course most people use about 70-80% per recommendations, so I think it would be hard to get a good sample of (crazy? ) people who use 50% for their charge limit.

I've definitely come more to your view that the driving factor here is calendar aging in the results people see, and you've well documented that SOC is crucial. So I think that you're right that the best strategy is to use as low an SOC as practicable for the use case.

However, it's still a mystery to me exactly how much variability we might see (or even fundamental differences in initial capacity due to design tweaks) in these cells. The degradation threshold in 2018/2019 vehicles was 76kWh. Not 77.8kWh like in new vehicles. Why was that? Were all the cells slightly less dense initially (they still had 77.8kWh "FPWN" nominal value in 2018/2019 vehicles)? Did they tweak the capacity of these cells very slightly over time? We just don't know.

I don't think we're seeing day-to-day variation of more than 1% or so for new packs. But over time, has the mean shifted a little, due to small iterations in the cell design? I don't know. I don't think it's realistic to think that the cell design was not changed at all over time as learning and cost reduction measures were rolled in.

To be clear, I don't think there's any way to answer these questions, nor is there anything an end user can do about these factors, so it's best just to follow your strategy of using the lowest SOC possible which is convenient for the user, if minimal calendar aging is desired.

Again as per akkis post, 80% is the worst soc and 70% is still wprse than 90% or 100% soc. It seems that main reason to not charge to 100% is to reduce cycling burden rather than storage/heat burden

 

[AlanSubie4Life]

Again as per akkis post, 80% is the worst soc and 70% is still wprse than 90% or 100% soc. It seems that main reason to not charge to 100% is to reduce cycling burden rather than storage/heat burden

Right, but it sounds like there are other reasons to be concerned about 100% charging. But even putting that aside, 100% to 70% is worse than 50% to 20% from a storage perspective.

Maybe I'm not getting what you're saying.

 

[Candleflame]

Keeping the SOC low as we say, below the about 57% step will basically cut the degradation in half. That should be quite safe to say.

The abolute main part of the people that see issues with higher degradation than they had expected use high SOC, leave the
car charged for time and also mostly live where the temperature have an negative effect.
There is a very few that use high SOC in warmer climate that see very low degradation.
Do we
Know anyone that use low SOC and have lost a lot?

As the research( a lot of research) show very consistent results, its very hard to see
that the same or very closely related cells should behave different mounted in a car.

I use low soc and have lost a lot despite my car sitting at 40 to 55% all day.

 

[Candleflame]

Right, but it sounds like there are other reasons to be concerned about 100% charging. But even putting that aside, 100% to 70% is worse than 50% to 20% from a storage perspective.

Maybe I'm not getting what you're saying.

Cycling from 100 to 75 is worse than 75 to 50 but if we are talking about storage then 90% is same as 55% (or whatever it was). With 80% beimg the worst.

This data was supported by the old model s survey where charging to 92% daycharge had the least degradation...

 

[Dave EV]

if we are talking about storage then 90% is same as 55% (or whatever it was). With 80% beimg the worst

No, this is not supported by any scientific study of batteries.

This data was supported by the old model s survey where charging to 92% daycharge had the least degradation...

And regardless, old Model S batteries are clearly not the same as Model 3 batteries. For sure, Model S 85 kWh and similar batteries (not 90 kWh pack cells, for example), all had very low rates of calendar life loss compared to the Model 3.

Which is a shame, really, but then the Model 3 batteries are able to charge a lot faster, so....

 

[Candleflame]

No, this is not supported by any scientific study of batteries.


And regardless, old Model S batteries are clearly not the same as Model 3 batteries. For sure, Model S 85 kWh and similar batteries (not 90 kWh pack cells, for example), all had very low rates of calendar life loss compared to the Model 3.

Which is a shame, really, but then the Model 3 batteries are able to charge a lot faster, so....

Yes it is.

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

Another potentially surprised model 3 owner here. I have my m3 performance for about 9 months, driven around 15kkm. I used obd reader with scan my Tesla app, and I see 75.5kwh available out of the original 82.1kwh. Meaning that I’m at around 92% SoH. Is that anticipated? Chargers are almost...

teslamotorsclub.com

 

[RG-M3]

Just got my 2nd Model 3, a long range. With my SR+ I used to use about 35% battery for my commute. I remember reading here that is best to always be charging (I have a tesla charger).

Now with my new LR, I use less than 20% battery. My question, should I still be charging every night? I could easily do 2-3 trips and still keep the battery in the 25 - 85% range.

What's better for the battery? What's better for my electric bill?

Thanks!

 

[Dave EV]

Yes it is.

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

Another potentially surprised model 3 owner here. I have my m3 performance for about 9 months, driven around 15kkm. I used obd reader with scan my Tesla app, and I see 75.5kwh available out of the original 82.1kwh. Meaning that I’m at around 92% SoH. Is that anticipated? Chargers are almost...

teslamotorsclub.com

Interesting - I did a deeper dive of the paper, and found the following, though:

• They seemed to be surprised that rate of capacity loss was lower at 90/100% compared to 70/80% as well
• Cells stored at 100% had other failure modes besides capacity loss that would be worrisome - high internal resistance.

I would be careful of drawing any general conclusions based on this paper aside from the specific chemistry (note that they decline to note the manufacturer of the cells) since this behavior is not common.

 

[AlanSubie4Life]

but if we are talking about storage

I’m talking about the practical case of storage (most of the time), with significant use. So most time would be spent stored at two specific endpoints (or maybe three endpoints, depending on the charging setup and frequency of use).

 

[Screenmare]

Went to 524 once after the update and now hovering around 500km estimated at 100%. Just under 5% degradation after one year if we go with the latest charge estimate of 501.06

View attachment 430211

 

[bedoig]

Dial back to 50% unless it doesn't work for you or you're trying to set some sort of capacity loss record.

This cracked me up, lol

 

[FlatSix911]

TMC members may be interested in the free service for predicting battery health across all-electric vehicles.
A free monthly report is provided to all owners who participate in their study.

Recurrent EV Battery Reports

Protect your EV battery with Owner Insights by Recurrent. This is a community of 20,000 drivers who foster EV adoption by demystifying range and battery health.

www.recurrentauto.com

EV Battery Monitoring for Electric Cars | Recurrent

 

[Steve446]

Every manufacturing process has a random variation in the output. It's fundamental. The only question is what the standard deviation is. It may be quite tight. Also, if it's truly random and there's no mean shifts over time, you'd expect it to be very tight at a pack level composed of 4416 cells.

That has been my point. it's having that "variation" under control. One could postulate that's the case and that the "variation" seen is not down to battery manufacturing activities but rather how the end users treat/exploit their cars/batteries. Many posts here point to that suggestion (my remark is not pejorative or critical of any of the posts concerned)

 

[Steve446]

Just got my 2nd Model 3, a long range. With my SR+ I used to use about 35% battery for my commute. I remember reading here that is best to always be charging (I have a tesla charger).

Now with my new LR, I use less than 20% battery. My question, should I still be charging every night? I could easily do 2-3 trips and still keep the battery in the 25 - 85% range.

What's better for the battery? What's better for my electric bill?

Thanks!

Good question. based on the arguments here, the less EFC you have the better.

 

[Steve446]

TMC members may be interested in the free service for predicting battery health across all-electric vehicles.
A free monthly report is provided to all owners who participate in their study.

Recurrent EV Battery Reports

Protect your EV battery with Owner Insights by Recurrent. This is a community of 20,000 drivers who foster EV adoption by demystifying range and battery health.

www.recurrentauto.com

EV Battery Monitoring for Electric Cars | Recurrent

My European based VIN (MIC) doesn't work with this site - it appears to be USA centric

 

[AAKEE]

I use low soc and have lost a lot despite my car sitting at 40 to 55% all day.

Did you use 40-55% since the cars was new?
Did you check the capacity initially, so you know from where ypu nu started?