The few times Tesla has addressed battery degradation, they have simply lied and dismissed it.

[DrChaos]

FWIW: without using any more or less fancy app, my 2020 LR AWD started at 504 km displayed range. Now, 144,000 km (89,500 miles) later, 100% charge equals 474 km. Maybe there is more to it, but to me, that's 6% less mileage than what I had when the car was new. I can live with that. I regularly charge the car to more than the recommended level but I start driving right after I reach my target, and then arrive at home at the recommended 80% (or 90% when that was the recommended maximum).
To me, range continues to be a non-issue.

You mean you cycle from say 95% to 80%? That's not the optimal practice.

 

[UncleCreepy]

You mean you cycle from say 95% to 80%? That's not the optimal practice.

Depends on what you are optimizing for. If battery life is all that matters, yes, then it's probably best to keep the car at 50% SoC in an air-conditioned garage.
To answer your question, it takes about 5% SoC to return home from my daily commute, so I used to charge to 95% and arrived at home at 90% when Tesla thought it was okay to go to 90% for daily use. Now that the changed their mind and think that the battery shouldn't be sitting at more than 80%, I charge to 85% and when I come home, it's at 80%.

My personal car is an automobile, and I like it that way. It happens fairly often that I decide later in the day that I want to go fly (roundtrip to the airport ~200 km) or that I have something to do in Ottawa, which is roughly 80 km away. I want to be able to jump into the car and just go. To me, it's not paramount to optimize the last little bit of longevity out of the battery when it can clearly handle being charged and stored at 80%.

Also, correct me if I'm wrong, but hasn't Tesla debunked that "supercharging is bad for you car" myth a while ago? That may have been an issue with older models, but as far as I remember that's no longer a thing.

 

[LostVector]

Depends on what you are optimizing for. If battery life is all that matters, yes, then it's probably best to keep the car at 50% SoC in an air-conditioned garage.
To answer your question, it takes about 5% SoC to return home from my daily commute, so I used to charge to 95% and arrived at home at 90% when Tesla thought it was okay to go to 90% for daily use. Now that the changed their mind and think that the battery shouldn't be sitting at more than 80%, I charge to 85% and when I come home, it's at 80%.

My personal car is an automobile, and I like it that way. It happens fairly often that I decide later in the day that I want to go fly (roundtrip to the airport ~200 km) or that I have something to do in Ottawa, which is roughly 80 km away. I want to be able to jump into the car and just go. To me, it's not paramount to optimize the last little bit of longevity out of the battery when it can clearly handle being charged and stored at 80%.

Also, correct me if I'm wrong, but hasn't Tesla debunked that "supercharging is bad for you car" myth a while ago? That may have been an issue with older models, but as far as I remember that's no longer a thing.

I'm finding the approach a bit puzzling. Why charge to 85 instead of 80? The way you are doing it, the car is spending some portion of time above 80% ... and possibly not an insignificant amount of time either, depending on when you put that charge in relative to your next drive.

 

[UncleCreepy]

I'm finding the approach a bit puzzling. Why charge to 85 instead of 80? The way you are doing it, the car is spending some portion of time above 80% ... and possibly not an insignificant amount of time either, depending on when you put that charge in relative to your next drive.

Like I wrote in #13: I start driving right after I reach my target, and then arrive at home at the recommended 80%. If less than half an hour is a significant amount of time, then so be it. I've logged almost 90k miles with my car so far and don't have any crazy degradation.
To me it's more important that I can drive my car if and when I need it without spending hours to charge it first. This convenience is worth dealing with a slightly increased wear that, at least in my view, probably won't make any difference.

 

[LostVector]

Like I wrote in #13: I start driving right after I reach my target, and then arrive at home at the recommended 80%. If less than half an hour is a significant amount of time, then so be it. I've logged almost 90k miles with my car so far and don't have any crazy degradation.
To me it's more important that I can drive my car if and when I need it without spending hours to charge it first. This convenience is worth dealing with a slightly increased wear that, at least in my view, probably won't make any difference.

if you drive within half an hour of charging, seems mostly fine. It just appeared that you were going off Tesla's recommendations, and the recommendation is pretty specifically not to charge past 80% except for trips ... the advice isn't "charge past 80% daily and bleed it off immediately". FYI, the battery undergoes more physical stress when charged to its highest levels, so charging and then driving immediately only avoids the calendar aging portion of degradation, but not cycling stress.

None of that is to say your approach is wrong ... if you sleep better with 80% range, then go for it.

 

[AAKEE]

Kyle Connor from out of spec says that there can be significant heat loss that throws off the measurement in the trips card if you do the 100 to 0 test at over 50 mph. Could that be what’s happening?

Yes. It’s not that significant though - I’ve never seen more than about 1% when I have actually been paying attention.

The battery capacity is very dependent on the load on the battery.
Therefore, any specification in Watt hours will be at a specific battery load.

Teslas “Nominal Full Pack” or Full pack when new is with a reasonably low load (like the EPA-test load or so).
Driving in a manner, or in environments causing the power to be higher than the “spec” will reduce the delivered energy (more heat losses).

Heres the reason: Increased load reduces the output voltage due to the internal resistance.
Energy (Watt hours) is:
*Average voltage* x *Ampehere hours*

The Amphere hours (milliamphere hours here) in this chart are the same, but most real tests shows a slight loss in these as well at higher loads.

When the voltage droop increases, the heat losses increases and the delivered energy goes down.

This is also the reason why I call the battery test in the service menu more or less bullshit. For one part it seems to use the degradation threshold as the initial capacity, and the other part is that a slooooow discharge will deliver more energy because of the lower heat losses.
With low power enough, the losses from increased internal resistance that we see during normal driving is “bypassed” and the result is a energy amount that we can not reporoduce at all during normal driving.

I have done quite many long drives with no loss comparing nominal remaining and delivered energy. These drives has not been very fast, but ~ 55-60mph or so.
Having a warm battery reduces the internal resistance and thereby the losses.

Also, the often incorrect Tessie app says 67.3 kWh, whatever you can take from that.

Tessie usually comes up with a quite good number of actual capacity.
Tessie did have severe problems to judge the initial capacity before (almost always wrong) but it seems better now.
Tessie also used the term “usable capacity” before which caused people to think the redult was the “netto capacity” and by adding the buffer they thought the degradation was very low, specially combined with the faulty original capacity.


Most of this seems better, not perfect yet but much better.

 

[AAKEE]

if you drive within half an hour of charging, seems mostly fine. It just appeared that you were going off Tesla's recommendations, and the recommendation is pretty specifically not to charge past 80% except for trips ... the advice isn't "charge past 80% daily and bleed it off immediately". FYI, the battery undergoes more physical stress when charged to its highest levels, so charging and then driving immediately only avoids the calendar aging portion of degradation, but not cycling stress.

None of that is to say your approach is wrong ... if you sleep better with 80% range, then go for it.

*Note: Everything below about batteries is facts from the sum of a huge amount of research.

There is a lot of misinformation or misunderstandings about batteries.

The “below 90%” which was changed to “80%” is not the daily number you should charge to.
It is the maximum daily.
Going below 81% removes the “80% is recommended for daily” note.

Lithium batteries is better of with low SOC.

First of all, following Teslas recommendations and using 80% daily will not be a problem during the warranty period at least. The battery will survive.
But it will not be with the lowest degradation possible.
Teslas advices does not aim for the lowest possible degradation. Instead, Tesla aim for the maximum possible window of usage, but still with a controlled degradation.

So, degradation is split into degradation from operation (cyclic aging) and time (calendar aging).

Cyclic aging is much less than most people think, and calendar aging is much more during the first 5-8 years than most people think.

- The calendar aging is not noticably higher at 100% than it is at 80%. Actually many tests even shows 80% to be worse than 100%. So if you charge to 80% daily, there is absolutely no need to drive asap after the 100% charge.
This picture shows a good sum of the hundreds of similar tests that the science gave us.

Same test, fewer test SOC’s but actual Tesla model S cells taken from a almost brand new S.

The use “stress” with batteries is often missleading. I recommend not focusing on text with such terms, like stress or microcracks etc. as they often misslead you on a bad road.
Find the charts that shows what actually happens with the capacity instead.

Many threads about degradation incorporates people stating very low degradation dedpute using 80-90% daily, and many times it has been needed to prove to them that they actually has more degradation than they thought. That part itself is not very fun, but needed to open the eyes about how batteries actually work and behaves.



@LostVector: Just answered your post as I had to use any of these posts….Not specifically aiming to your statements.

 

[AAKEE]

Overall, I’m not particularly happy with the degradation. As an aspiring engineer, it’s something I just am going to think about and notice. I’ve always kept my car in % mode as the miles is completely useless. I’m going to unfortunately have to baby the performance I have on order as I don’t want to really have to be thinking like this again. Also apparently the 82kwh Panasonic batteries degrade much more too. What ever happened to this “million mile” battery?

Take an hour or two, read my posts and others about calendar aging. Search for example for calendar aging + AAKEE, then you will find useful posts to learn about what is degrading your battery, and how it does that.
Knowing that you can counter it be reducing the factors that causes higher degradation - or just leave it to what it is, if you get less unhappy knowing the facts behind.

 

[AAKEE]

That said, from pure interrest I did make a excel sheet for my first Tesla with the planned degradation curve.
I did have to adjust it about 9 months, as I found my average SOC was slightly lower and the verage cell temp also was a little lower than I did expect (data from logs). After that adjustment, the car did follow the curve spot on until I sold it after 2.5 years.

I did make a new sheet for my MSP, this time I added the possibillity to follow up the actual nominal full pack and nominal remaining at full charges.
Blur line is the expected battery capacity after degradation month per month, amber/orange is the nominal full pack. Again, it follows the curve.
I can see that my battery should be around 94.5 kWh at 5 years age.

 

[QtownTaxiGreg]

To me it's more important that I can drive my car if and when I need it without spending hours to charge it first.

You mentioned the airport run. If you had it charged at 60% you would have enough to get there and back and your calendar aging would drop back from the far end of the curve where it gets much worse. See Aakee's post with the multiple colours for temperature, degradation v SOC storage tests.

 

[AAKEE]

Why charge to 85 instead of 80? The way you are doing it, the car is spending some portion of time above 80%

There is no issue with having the car at 85% instead of 80%.

There’s an issue with what people think is bad, and what really is.
- Most things is not bad, at all but people thinknit is, so they avoid it at no gain.

 

[LostVector]

There is no issue with having the car at 85% instead of 80%.

There’s an issue with what people think is bad, and what really is.
- Most things is not bad, at all but people thinknit is, so they avoid it at no gain.

My point was more that regardless of what you think the impact is, if one is trying to follow Tesla’s recommended charging procedure, then charging to 85 and draining it back down daily is not that.

 

[DrChaos]

*Note: Everything below about batteries is facts from the sum of a huge amount of research.

There is a lot of misinformation or misunderstandings about batteries.

The “below 90%” which was changed to “80%” is not the daily number you should charge to.
It is the maximum daily.
Going below 81% removes the “80% is recommended for daily” note.

Lithium batteries is better of with low SOC.

First of all, following Teslas recommendations and using 80% daily will not be a problem during the warranty period at least. The battery will survive.
But it will not be with the lowest degradation possible.
Teslas advices does not aim for the lowest possible degradation. Instead, Tesla aim for the maximum possible window of usage, but still with a controlled degradation.

So, degradation is split into degradation from operation (cyclic aging) and time (calendar aging).

Cyclic aging is much less than most people think, and calendar aging is much more during the first 5-8 years than most people think.

- The calendar aging is not noticably higher at 100% than it is at 80%. Actually many tests even shows 80% to be worse than 100%. So if you charge to 80% daily, there is absolutely no need to drive asap after the 100% charge.
This picture shows a good sum of the hundreds of similar tests that the science gave us.
View attachment 1048279

Same test, fewer test SOC’s but actual Tesla model S cells taken from a almost brand new S.
View attachment 1048280

The use “stress” with batteries is often missleading. I recommend not focusing on text with such terms, like stress or microcracks etc. as they often misslead you on a bad road.
Find the charts that shows what actually happens with the capacity instead.

Many threads about degradation incorporates people stating very low degradation dedpute using 80-90% daily, and many times it has been needed to prove to them that they actually has more degradation than they thought. That part itself is not very fun, but needed to open the eyes about how batteries actually work and behaves.



@LostVector: Just answered your post as I had to use any of these posts….Not specifically aiming to your statements.

this post should be a sticky or part of FAQ for all such questions.