Model 3 SR+ LFP Battery Range, Degradation, etc Discussion

[gtg465x]

Without reading the whole post in detail, I have seen that report and if I remember it correct, the same researchers even got another report out with contradicting result.
Other reports have not seen the same thing for small cycles.

The same researchers did have another related study, but it was not contradictory. The first study was where they noticed the phenomenon. The second study, which I linked to, was where they explored it deeper and figured out an explanation for why it was happening. I haven't come across another study that contradicts the findings.

So, 4-5000 FCE cycles equals one miljon mile or so. This in turn means that the degradation per year or 10K mile or whatever unit we use that comes from cycles/ driving will be almost neglibe.

If you look at the graph I posted, it's for 350 full equivalent cycles, which is only around 75-100k miles in this car, and the 40-60% cycles induced 8.6% capacity loss during that time, and that's not even including much calendar aging. The batteries may well last 4-5000 FEC, but that doesn't mean they have no capacity loss during that time. It's also important to note that the study is examining a different phenomenon than the normal cyclic aging process for LFP cells, which may not present itself with the normal cyclic aging test methodology.

The conclusion is, (the same as for NCA and NMC) that if we would like to minimize degradation we need to focus on the calendar aging as it will be the dominating degradation factor for very long on LFP (as the cyclic aging is negligible.

If we would need to prioritize between reducing calendar and cyclic aging the choice is clear.

Personally, I will be focusing on both. I don't see a need to only focus on one. According to the study, doing 15-35% or 15-50% cycles will be much better than 30-50% cycles, and those cycles would also have lower average SOC, and thus lower calendar aging as well. Similarly, if you want to charge to 100% occasionally, doing 20-100% cycles should be much better than 50-70% cycles, and both should have roughly the same average SOC, so you'd likely get similar calendar aging, but less capacity loss from cycling.

 

[gtg465x]

Thanks. I was leaning toward 50% but this thread has me confused.

Rich

The study I posted is only referring to how you cycle the battery, not how you store it. Storing at 50% is good.

 

[gtg465x]

Well first things first: thanks very much for taking the time to post the link to this study and pertinent information from the study.

My battery pretty much sits between 37% and 55% at any given time, and probably (because I don’t drive that much and charge up as soon as I get home) spends most of its time at 55%. I guess according to the chart I am maybe getting somewhere around 7.5% capacity loss per 350 FEC?

Now I am going to try to extrapolate: If an FEC for my car is roughly equivalent to 240 miles of driving, then I would likely average an FEC somewhere around every 10 days that I drive it. Since I drive around 20 days a month, perhaps I tend to complete 2 FEC’s per month. I have had the car for about 20 months, so I have perhaps 40 total FEC’s under my belt so far with this car. This kind of matches up with 43.75, which is the number I get from dividing my total odometer miles (10500) by 240.

If the capacity loss is proportional and I have driven the car for somewhere around 1/8th of the 350 FEC‘s measured in the study, then my capacity loss so far should be 7.5% divided by 8 = a little less than 1%.

Baluchi, on the other hand, who drives about 5 times as much as I do, at this point shows about the same capacity loss as I do. It would be interesting to plug in some his numbers as far as what ranges his battery is usually operating within, and what his expected capacity loss would be for those ranges. Maybe Baluchi and I equal out because though he loses more range than I do because of increased miles, I in turn lose more range because of operating between 37% to 55% most of the time…

Yes, since you drive so few miles, calendar aging is your primary concern, but it's still possible you could be doing slightly better if you weren't only charging in the middle of the SOC range (like maybe you would have 243 miles (4% degradation) at 100% instead of 240 (5% degradation)).

You said you and Baluchi have owned your cars for about the same amount of time and have roughly the same degradation, even though he drives a lot more miles than you.

It's possible that you both have roughly the same calendar aging (let's assume 4%, although storage temperatures and average SOC affect this, so in reality, it could be different), and you also have the same cyclic aging (let's assume 1%). His cyclic aging might be 1% because he's gone so many miles, but yours might be just as high not because you've gone miles, but because you've increased your cyclic aging by staying within the middle of the SOC range.

It's also possible that all of Baluchi's 5% degradation is from calendar aging, whereas your calendar aging is less than his (4%) because you keep your SOC lower, but while he has 0% loss from cyclic aging because he hits those voltage gradients, you have 1% loss from cyclic aging because you stay within the flat voltage range.

Maybe if you had charged 17-35% this whole time instead of 37-55%, you would still be at roughly 0% cyclic degradation and only 4% total degradation (only from calendar aging, although that might be lower as well with lower SOC). Whether the extra stress of complicating your charging habits and being at such low SOC is worth it is another question. With how few miles you drive, it's probably not worth changing anything.

 

[RichAZ/CapeCod]

The study I posted is only referring to how you cycle the battery, not how you store it. Storing at 50% is good.

Thanks!

Rich

 

[pipp]

Yes, since you drive so few miles, calendar aging is your primary concern, but it's still possible you could be doing slightly better if you weren't only charging in the middle of the SOC range (like maybe you would have 243 miles (4% degradation) at 100% instead of 240 (5% degradation)).

You said you and Baluchi have owned your cars for about the same amount of time and have roughly the same degradation, even though he drives a lot more miles than you. It's possible that you both have roughly the same calendar aging (let's assume 4%, although storage temperatures affect this, so in reality it could be different), and you also have the same cyclic aging (let's assume 1%). His cyclic aging might be 1% because he's gone so many miles, but yours might be just as high not because you've gone miles, but because you've increased your cyclic aging by staying within the middle of the SOC range. Maybe if you had charged 17-35% this whole time instead of 37-55%, you would still be at roughly 0% cyclic degradation and only 4% total degradation (only from calendar aging, although that might be lower as well with lower SOC). Whether the extra stress of complicating your charging habits and being at such low SOC is worth it is another question. With how few miles you drive, it's probably not worth changing anything.

Yep that is why I’m interested in seeing where Baluchi’s operating range numbers place him on the chart you posted (and linked to).

 

[gtg465x]

Yep that is why I’m interested in seeing where Baluchi’s operating range numbers place him on the chart you posted (and linked to).

I edited my response after you replied, but here's another potential scenario I added:

It's also possible that all of Baluchi's 5% degradation is from calendar aging, whereas your calendar aging is less than his (4%) because you keep your SOC lower, but while he has 0% loss from cyclic aging because he hits those voltage gradients, you have 1% loss from cyclic aging because you stay within the flat voltage range.

 

[theothertom]

Picture shows degradation (full range) on 2021 SR+ with LFP.

Why does the range increase (degradation decreases) around 50,000 km? Not enough data points?

 

[AAKEE]

Why does the range increase (degradation decreases) around 50,000 km? Not enough data points?

I guess there is two different midels incorporated in the same graph.
Teslalogger does seem to have some mixes somtimes.
Look at these two as two models in the same graph:

 

[gtg465x]

That has always annoyed me about the Teslalogger.de chart. The top is the 2022+ Model 3 RWD with 60 kWh LFP battery and 272 mi / 438 km range. The bottom is possibly the 2021 SR+ with 263 mi / 423 km range, but that didn't even have an LFP battery. There was a made in China SR+ with a smaller 55? kWh LFP battery, but I thought that one was rated for 253 mi / 407 km, which doesn't line up with the bottom plot points. Anyways, the chart should maybe look something like this, but it's hard to tell whether the in between points are the smaller battery model with very little degradation or the bigger battery model with bad degradation. The plot points past 50k km can probably be ignored anyways, because they're outliers that drive an insane distance per year and probably won't be representative of the rest of the fleet when they get to that point (since calendar aging is the main factor). And speaking of calendar aging, I wish they had plots over time instead of just for distance.

 

[AAKEE]

That has always annoyed me about the Teslalogger.de chart. The top is the 2022+ Model 3 RWD with 60 kWh LFP battery and 272 mi / 438 km range. The bottom is possibly the 2021 SR+ with 263 mi / 423 km range, but that didn't even have an LFP battery. There was a made in China SR+ with a smaller 55? kWh LFP battery, but I thought that one was rated for 253 mi / 407 km, which doesn't line up with the bottom plot points. Anyways, the chart should maybe look something like this, but it's hard to tell whether the in between points are the smaller battery model with very little degradation or the bigger battery model with bad degradation. The plot points past 50k km can probably be ignored anyways, because they're outliers that drive an insane distance per year and probably won't be representative of the rest of the fleet when they get to that point (since calendar aging is the main factor). And speaking of calendar aging, I wish they had plots over time instead of just for distance.

View attachment 928135

Very good post.

I think the SR+ with 2170L / 55.4 kWh batt had 263 miles, and the smaller LFP was 55.1 (if my memory doesnt fail?).

Most probably the same constant (or very small adjustment for weight?) so the displayed range would be about 263 mi or 423 km ? Im not sure it ever dud get a ofgicial EPA range, as they might have not been sold in US?

The degradation vs time will be quite telling, the day prople will start to use that.
Probably we will need to see a lot of batteries failing on age regardless of the miles driven before this insigt reach out, so we need to wait s little bit more.
It looks like older model S is starting to show this, so maybe not too long wait…

 

[NYHeel]

I'm not terribly worried but I've noticed a fairly sharp linear progression in EPA range on my new Model 3 RWD since I started using TeslaFi. I took delivery on 2/27 this year and through one month (on 3/26) I still had the full EPA range on a full charge of 272.47 per TeslaFi as well as my memory. That was the first charge I did when I started using TeslaFi. Over the last 2.5 weeks my EPA range is now down to 268.5 which seems like a steep drop for such a short period of time. Also, the change has been fairly linear and consistent.

This includes 6 charges to 100% starting on 3/26 through my last charge that ended this morning on 4/14. This has all been at level 1 and 2 charging as I haven't yet done any supercharging yet. I charged at Level 1 the first two weeks I had the car as my Level 2 wasn't installed yet. With that said, our driving has been very efficient of late and though our rated range is 268.5, our estimated range is actually at 293.78. That's per TeslaFi which I believe just comes right off of the Energy app on the car. We frequently get drives of around 200-210 Wh/mile even on drives that include a decent amount of highway driving.

Looking at another app, Recurrent Auto is giving me a range score of 102 so maybe my range isn't degrading. I guess I'm just not sure what I should be looking at to determine real battery degradation vs. efficient driving habits. Obviously, 1.5% battery degradation (assuming it's legit) doesn't worry me. But the quick rate (occuring in less than 3 weeks and over less than 45 days of total car ownership) and the linear looking line does worry me a little bit. Do I have anything to worry about based on these stats?

 

[pipp]

I'm not terribly worried but I've noticed a fairly sharp linear progression in EPA range on my new Model 3 RWD since I started using TeslaFi. I took delivery on 2/27 this year and through one month (on 3/26) I still had the full EPA range on a full charge of 272.47 per TeslaFi as well as my memory. That was the first charge I did when I started using TeslaFi. Over the last 2.5 weeks my EPA range is now down to 268.5 which seems like a steep drop for such a short period of time. Also, the change has been fairly linear and consistent.
View attachment 928341

This includes 6 charges to 100% starting on 3/26 through my last charge that ended this morning on 4/14. This has all been at level 1 and 2 charging as I haven't yet done any supercharging yet. I charged at Level 1 the first two weeks I had the car as my Level 2 wasn't installed yet. With that said, our driving has been very efficient of late and though our rated range is 268.5, our estimated range is actually at 293.78. That's per TeslaFi which I believe just comes right off of the Energy app on the car. We frequently get drives of around 200-210 Wh/mile even on drives that include a decent amount of highway driving.

Looking at another app, Recurrent Auto is giving me a range score of 102 so maybe my range isn't degrading. I guess I'm just not sure what I should be looking at to determine real battery degradation vs. efficient driving habits. Obviously, 1.5% battery degradation (assuming it's legit) doesn't worry me. But the quick rate (occuring in less than 3 weeks and over less than 45 days of total car ownership) and the linear looking line does worry me a little bit. Do I have anything to worry about based on these stats?

I’m not one of the experts but here’s my 2 bits: just keep monitoring it. My guess is that it might pop back up a mile or two but then after another couple of months settle back in to where you are now. That’s just a guess for fun. But there really isn’t anything you can do at this point besides keep monitoring.

 

[3sr+buyer]

I think the SR+ with 2170L / 55.4 kWh batt had 263 miles, and the smaller LFP was 55.1 (if my memory doesnt fail?).

Most probably the same constant (or very small adjustment for weight?) so the displayed range would be about 263 mi or 423 km ? Im not sure it ever dud get a ofgicial EPA range, as they might have not been sold in US?

Some 2021 SR+ in the US had LFP batteries, with rated range of 253 miles or some such.

 

[NYHeel]

I’m not one of the experts but here’s my 2 bits: just keep monitoring it. My guess is that it might pop back up a mile or two but then after another couple of months settle back in to where you are now. That’s just a guess for fun. But there really isn’t anything you can do at this point besides keep monitoring.

Yeah, just hoping it at least levels out somewhat soon. I just don't want it to keep going down every time I charge the car. The crazy thing is that my son took the car on a pretty long round trip today and it's currently at 44% and projects to show another sizable drop in range from just one day. We'll see what happens as 44% isn't super precise without more decimal places but it's not a good sign.

 

[pipp]

Yeah, just hoping it at least levels out somewhat soon. I just don't want it to keep going down every time I charge the car. The crazy thing is that my son took the car on a pretty long round trip today and it's currently at 44% and projects to show another sizable drop in range from just one day. We'll see what happens as 44% isn't super precise without more decimal places but it's not a good sign.

I think when the battery gets to be 70% of its original state is when tesla is obligated to provide you with a replacement battery. At your present rate of degradation that would be around 3 years from now. But unless you are having terrible luck on this car, that rate will slow down.

 

[AAKEE]

I think when the battery gets to be 70% of its original state is when tesla is obligated to provide you with a replacement battery. At your present rate of degradation that would be around 3 years from now. But unless you are having terrible luck on this car, that rate will slow down.

Another way to see it is the scientific way. There is no battery lottery, really.

268.5 out of 272-273 is roughly 1.5%. This is within the degradation we could expect. Most probablyt there is not a noticable difference between @NYHeel ’s car and others, its probably a BMS thing.

If the battery follows the calendar aging chart (or better) we could expect this 1.5% today to be some 8.5% after three years, not 30%.
And 14% after eight years.

 

[AlanSubie4Life]

There was a made in China SR+ with a smaller 55? kWh LFP battery, but I thought that one was rated for 253 mi / 407 km,

Some 2021 SR+ in the US had LFP batteries, with rated range of 253 miles or some such.

They adjusted to 262 miles I believe after some period of time.

In the linked thread I think at some point we got enough data to determine the degradation threshold for 262. One of these days I should scrounge around and make a proper spreadsheet capturing all the data, but I just have not bothered. It’s all out there. (Basically it would be useful to have a table of FPWN, degradation threshold, typical capacity when new, and rated range when new (after any initial software adjustments to the constant), for each vehicle. The constant would be the ratio of degradation threshold to rated miles max.)

Note this was not 263. Totally different.

 

[AlanSubie4Life]

There is no battery lottery, really.

I refuse to believe this until there is an explanation for @KenC ’s vehicle. Surprisingly few outliers like that though, for sure.

So mostly I agree.

 

[Baluchi]

Yep that is why I’m interested in seeing where Baluchi’s operating range numbers place him on the chart you posted (and linked to).

Mostly I'm charging between zones 3 and 4, or between 4 and 5 on that chart.

 

[amg1923]

Another way to see it is the scientific way. There is no battery lottery, really.

268.5 out of 272-273 is roughly 1.5%. This is within the degradation we could expect. Most probablyt there is not a noticable difference between @NYHeel ’s car and others, its probably a BMS thing.

If the battery follows the calendar aging chart (or better) we could expect this 1.5% today to be some 8.5% after three years, not 30%.
And 14% after eight years.

View attachment 928491

Does this graph imply that if we store our car at 0%, the calendar degradation will disappear?

If this is the case, why does every manufacturer recommends to quickly charge when you get to low percentages because the battery could be damaged? Are they lying?