8% degradation after 9k miles, wtf?

[Chewy986]

Hello everyone!

So, I read a lot about proper battery maintenance (or so I thought), but I’m sitting on 8% degradation after 5 months and 9k miles… which sounds like way higher than most people experience and is pretty worrisome.

I charge my battery to 80% everyday as soon as I get home from work. I drive about 80 miles round trip and use around 30% of the battery daily, so when I get home it’s around 50%. I have never charged it above 85% and have been down to 17% only once and very briefly. I charge with my 220v 50a garage plug. I have never supercharged.

Based on the above fact pattern I expected to be in really good shape, yet my results are so far sub par.

I did buy the acceleration boost but mostly drive on the highway and rarely use it. I typically cruise 70-80mph which may be part or the problem. I live in Houston which is a hot climate for the battery and I generally have the AC on pretty high. I suppose the hot environment mixed with AC load and 80mph cruising speed is a bit taxing but I haven’t heard much discussion on it.

Any advice on how I might curb this degradation? Did I get a lemon?

Today I read 57% battery yielding 170miles for a 298mi capacity (or about 8.5% degradation vs new). I drive a model Y LR which is quoted at 326mi new)

 

[Candleflame]

They should throw out the rated range.
That is the range when it's new and drops by 10% very very quickly.

i agree, the governments have to introduce advertising standards... and teslas "gas cars may lose some efficiency" is really a stupid argument when your petrol car is maybe 2% less efficient after 300k kms....

 

[Candleflame]

Hello everyone!

So, I read a lot about proper battery maintenance (or so I thought), but I’m sitting on 8% degradation after 5 months and 9k miles… which sounds like way higher than most people experience and is pretty worrisome.

I charge my battery to 80% everyday as soon as I get home from work. I drive about 80 miles round trip and use around 30% of the battery daily, so when I get home it’s around 50%. I have never charged it above 85% and have been down to 17% only once and very briefly. I charge with my 220v 50a garage plug. I have never supercharged.

Based on the above fact pattern I expected to be in really good shape, yet my results are so far sub par.

I did buy the acceleration boost but mostly drive on the highway and rarely use it. I typically cruise 70-80mph which may be part or the problem. I live in Houston which is a hot climate for the battery and I generally have the AC on pretty high. I suppose the hot environment mixed with AC load and 80mph cruising speed is a bit taxing but I haven’t heard much discussion on it.

Any advice on how I might curb this degradation? Did I get a lemon?

Today I read 57% battery yielding 170miles for a 298mi capacity (or about 8.5% degradation vs new). I drive a model Y LR which is quoted at 326mi new)

AC does not use much power and isnt relevant when you drive at 80 mph. 8% degradation after 9k miles sounds about normal.

 

[TomServo]

Mine had a steady decline to about 8% at about the 9K mile mark and seems to be hovering there, I'm at 15,400 miles today.

That's according to the STATS app. Not sure how accurate that is, but when set my charging slider to 100% it tells me my "max range is 292 miles". My best when new was "312". FYI my 2020 Y was rated at 316.

 

[DanDi58]

As most people know, looking at what the car or an app says your max miles at 100% charge isn't really an accurate assessment of degradation. There are other reasons why it may not be accurate. That said, I'll add a data point - TezLab indicates 301 miles on my car with just under 12k miles; with the original rating at 326, I guess that would mean just under 8% 'degradation'. However, I have performed no BMS management activities so I don't really think it's that high. And I don't really care.

 

[AAKEE]

but I’m sitting on 8% degradation after 5 months and 9k miles… which sounds like way higher than most people experience and is pretty worrisome.

I charge my battery to 80% everyday as soon as I get home from work. I drive about 80 miles round trip and use around 30% of the battery daily, so when I get home it’s around 50%. I have never charged it above 85% and have been down to 17% only once and very briefly.

80% is about, or close to, the worst SOC you can have if you try to minimize degradation.

Degradation is divided into two types:
-Calendar aging
-Cyclic aging

Calendar aging is the dominant part during the first hears for most people.
80% SOC might ”eat” about 5-7% the first year.
To minimize degradation:
- The lower the SOC the lower the calendar aging.
- The smaller the cycles the lower the cyclic aging.
- The lower the cycle is positioned in the SOC range the lower the cyclic aging.

The standard ”forum truth” is that 80% is the best storage SOC and that lithium batteries breaks by SOC below 20%.
(None pf these are true)

Cyclic aging is: Time x SOC x temperature.

Temperature (lower is better) is often hard to affect.
SOC: Dont use higher SOC than needed if you like to keep the degradation low.
Time: If possible, charge ”late” so the time at higher SOC will be shorter.

You ”can not” loose 8% from your cycles and 9K mi.
You probably cannot loose 8% in 5 months unless the average temps have been 50 degree Celcius( some 120F).
So your real degradation of range probably is lower than the 8% you see.

You have not used the whole range of the battery capacity. Your battery havent really seen the endpoints of the battery.
Drive it down to a few to 10%, let the car sit for a night, no sentry and no other things running, do not use the app etc during this time( the car need to sleep for some hours to se the resting voltage).
Charge full( let it charge until it stops) and then let the car rest for a couple of hours, sentry off, do not use the app etc. Letting the car sleep is important.

I guess there this would get the BMS on track and increase the screen range.
After this, the range probably increases.
(Do not look for range or degradation in the app, all ”degradation” values should be taken from the car screen.)
It might take more than one big cycle to get the BMS to show the correct value.

 

[Candleflame]

As most people know, looking at what the car or an app says your max miles at 100% charge isn't really an accurate assessment of degradation. There are other reasons why it may not be accurate. That said, I'll add a data point - TezLab indicates 301 miles on my car with just under 12k miles; with the original rating at 326, I guess that would mean just under 8% 'degradation'. However, I have performed no BMS management activities so I don't really think it's that high. And I don't really care.

It is extremely accurate as has been discussed and prooven here time ans time again. With perhaps the exception of a messed up voltage table but this is rare.

 

[ranss12]

Recurrentauto says my May 2021 MYLR has a range of 299 miles. Here is the comparison between my Y and others. I'm way worse.

I have close to 16,000 miles on my Y - original range was supposed to be 326 miles. 299 miles = 8.7% degradation. At this point I'm not worried - if the degradation doesn't slow (as many posters say it will), then I guess I'll just get a warranty replacement battery in 3 or 4 years.
Incidentally, I do little Supercharging and my lifetime Watt-hour/mile is 233, so my Y has been treated pretty gently.

 

[jcanoe]

Recurrentauto says my May 2021 MYLR has a range of 299 miles. Here is the comparison between my Y and others. I'm way worse.

View attachment 775757

I have close to 16,000 miles on my Y - original range was supposed to be 326 miles. 299 miles = 8.7% degradation. At this point I'm not worried - if the degradation doesn't slow (as many posters say it will), then I guess I'll just get a warranty replacement battery in 3 or 4 years.
Incidentally, I do little Supercharging and my lifetime Watt-hour/mile is 233, so my Y has been treated pretty gently.

Your Model Y is just one year ahead of the class, that's all.

 

[Chewy986]

I am the original poster and wanted to mention this is resolved. The answer, which isn’t great, is that the math they use to estimate max capacity has some serious limitations.

When I initiated this post I never let my batter “rest” (sit at constant charge, with sentry mode off, for 4-6hrs) at less than 60% charge. This never gave their math equation enough data points to appropriately estimate the max capacity. I flipped my practice and let it rest often between 20-60%… and within a month my calculated max capacity jumped up from a low of 285 back up to almost 310…

I then let it charge and sit around 90% a few times and it dropped back to low 300’s.

The lesson is that unless you actively manage your soc levels during rest periods the max distance at full charge estimate may be low or high by 20miles or possibly more.

 

[FloridaSun]

I am the original poster and wanted to mention this is resolved. The answer, which isn’t great, is that the math they use to estimate max capacity has some serious limitations.

When I initiated this post I never let my batter “rest” (sit at constant charge, with sentry mode off, for 4-6hrs) at less than 60% charge. This never gave their math equation enough data points to appropriately estimate the max capacity. I flipped my practice and let it rest often between 20-60%… and within a month my calculated max capacity jumped up from a low of 285 back up to almost 310…

I then let it charge and sit around 90% a few times and it dropped back to low 300’s.

The lesson is that unless you actively manage your soc levels during rest periods the max distance at full charge estimate may be low or high by 20miles or possibly more.

I noticed the same thing.. I charged to 90 - 92% for a few times and my estimated range dropped to 305 miles.. I did charge to 70 - 80% a few times recently and I'm at about 312 to 315 miles 100% estimate. So, the estimated range and capacity depends a lot of your charging habits. I'm at about 25k miles and current estimated 100% range is 314 miles. If this is correct, my degradation is below average.. It has been almost 11 months since I got the car.. 3.5% degradation (my original range was 326 miles)

 

[DanDi58]

I am the original poster and wanted to mention this is resolved. The answer, which isn’t great, is that the math they use to estimate max capacity has some serious limitations.

When I initiated this post I never let my batter “rest” (sit at constant charge, with sentry mode off, for 4-6hrs) at less than 60% charge. This never gave their math equation enough data points to appropriately estimate the max capacity. I flipped my practice and let it rest often between 20-60%… and within a month my calculated max capacity jumped up from a low of 285 back up to almost 310…

I then let it charge and sit around 90% a few times and it dropped back to low 300’s.

The lesson is that unless you actively manage your soc levels during rest periods the max distance at full charge estimate may be low or high by 20miles or possibly more.

Curious as to how you found this out. Also, it's important to note that what you're talking about is the maximum range estimate, as you noted - not battery degradation. 2 different thing.

 

[qdeathstar]

Recurrentauto says my May 2021 MYLR has a range of 299 miles. Here is the comparison between my Y and others. I'm way worse.

View attachment 775757

It’s only like a 7 mile difference though…. Between you and average. So I’m not sure I would describe that as way worse.

 

[Dennisis]

It’s only like a 7 mile difference though…. Between you and average. So I’m not sure I would describe that as way worse.

And if you have the 20's (don't see your config) your actual range was never 326. Like you, I signed up for that Recurrentauto report some time ago but I think it's worthless, I wouldn't stress - too many factors and the range estimate can vary widely for reasons detailed elsewhere.

 

[AAKEE]

Curious as to how you found this out. Also, it's important to note that what you're talking about is the maximum range estimate, as you noted - not battery degradation. 2 different thing.

The range indication at the battery symbol is actually a battery capacity meter, graded in miles/kwh available.
So, it show battery degradstion indirectly.

Or it try to show, as the capacity calculation depend on seeing the open circuit voltage (OCV) at different SOC.
The true SOC is found out by reading the OCV when the battery have been at rest for a while.

 

[AAKEE]

I am the original poster and wanted to mention this is resolved. The answer, which isn’t great, is that the math they use to estimate max capacity has some serious limitations.

When I initiated this post I never let my batter “rest” (sit at constant charge, with sentry mode off, for 4-6hrs) at less than 60% charge. This never gave their math equation enough data points to appropriately estimate the max capacity. I flipped my practice and let it rest often between 20-60%… and within a month my calculated max capacity jumped up from a low of 285 back up to almost 310…

I then let it charge and sit around 90% a few times and it dropped back to low 300’s.

The lesson is that unless you actively manage your soc levels during rest periods the max distance at full charge estimate may be low or high by 20miles or possibly more.

Very good it worked out just as it “should”.

The BMS is good at keeping track of the capacity and for most it probably work fine without and BMS calibration tricks.

For me, mostly charging to 55% with about 20-35% cycles it overestimate the capacity slightly.
I had to drive down to -2% SOC to put it on track, and when reverting to 55% charges it creep up to the slight overestimate.

 

[Tonedog77]

Over 100k miles on test they have found these batteries have an initial drop of 5-7 percent rather fast then slow down a ton over the life of the battery most people saw a 5-7 drop around the first 15-30k miles and then barely any throughout the next 70k

 

[AAKEE]

Over 100k miles on test they have found these batteries have an initial drop of 5-7 percent rather fast then slow down a ton over the life of the battery most people saw a 5-7 drop around the first 15-30k miles and then barely any throughout the next 70k

So all owners here at TMC that have 10 to 14% degradation have driven their Model 3’s and Y 170.000 miles?

No.

Degradation do not only happen from miles/cycles. In fact the calendar aging is the dominant degradation source for at least the five first years for an car that is driven average miles/year.

Cyclic aging, that comes from the miles, is more or less ”flat” with about the same degradation per mile driven.

 

[v8eater]

The display in the car does NOT show battery degradation. The only way to truly get an accurate number is to charge the car to 100 percent and drive it until it is dead and measure the kwh used. That is the only way.

 

[AAKEE]

The display in the car does NOT show battery degradation. The only way to truly get an accurate number is to charge the car to 100 percent and drive it until it is dead and measure the kwh used. That is the only way.

Well, as I wrote, it shows the BMS judgement of the remaining capacity in the battery. Showing the estimated remaining battery capacity is also indirectly showing the estimated degradation.
It wont be a exact, true number as in a full discharge test but in many cases it is not very far away.

 

[Tonedog77]

So all owners here at TMC that have 10 to 14% degradation have driven their Model 3’s and Y 170.000 miles?

No.

Degradation do not only happen from miles/cycles. In fact the calendar aging is the dominant degradation source for at least the five first years for an car that is driven average miles/year.

Cyclic aging, that comes from the miles, is more or less ”flat” with about the same degradation per mile driven.

actually no never said anything about 10-14, but that is the average at 100k based on tests. And tracking data has shown alot happens at the very beginning and then very slowly over time. theres people who have done test at 100k through 200k miles that show a mere 8-10 percent total lost of which most happen in the first year of the battery, it slows down drastically after the first drop. Look up out of spec and his 100k breakdown showing hes right around 12% down from new at 100k miles