Battery Degradation Year 1

[AAKEE]

It is the net value without the buffer. Tessie can't see or know the buffer.

You might wanna look at these two posts:

Tessie usable capacity

BMS data from the same car

If the case was not made clear before, here is one example of this:

The BMS ‘Nominal full pack’ and Tessies “Usable capacity” is the same value. Both includes the buffer.

 

[James@Tessie]

You might wanna look at these two posts:

Tessie usable capacity

BMS data from the same car

If the case was not made clear before, here is one example of this:

The BMS ‘Nominal full pack’ and Tessies “Usable capacity” is the same value. Both includes the buffer.

Thanks! I've updated the docs and UI terminology.

 

[AAKEE]

Thanks! I've updated the docs and UI terminology.

Nice!

 

[rwojo]

78.5 is what other cars with the same config reported at 0 mi odometer. Hard to tell if you won the battery pack lotto or if there's something different with your battery versus other owners with that config.

There's a sticker on the front right side of the battery that can provide some insight. You can see it if you look under the car around the front right wheel. If you Google that model you might be able to find out the capacity when new that's been measured with hardware (e.g. OBD scanner or a car teardown.) Otherwise some people use ScanMyTesla with an OBD scanner to verify the underlying battery pack data.

For those that are able to get the the nominal and buffer, perhaps allowing those users to type in the values for now until there is a way via the API could work as a stop gap measure.

I finally got Scan My Tesla installed on my 2023 MYLR and it is showing 78.7kWh for the nominal full pack which differs only slightly from the 78.5kWh that Tessie defaults to, so I corrected that. Looks like that's apples-to-apples (includes buffer) so that's good.

Now Tessie is showing 0.1% degradation, with about 4,500mi since Feb 2023.

Is that the best estimate possible without doing a full drain/charge test via service menu?

 

[James@Tessie]

For those that are able to get the the nominal and buffer, perhaps allowing those users to type in the values for now until there is a way via the API could work as a stop gap measure.

I finally got Scan My Tesla installed on my 2023 MYLR and it is showing 78.7kWh for the nominal full pack which differs only slightly from the 78.5kWh that Tessie defaults to, so I corrected that. Looks like that's apples-to-apples (includes buffer) so that's good.

Now Tessie is showing 0.1% degradation, with about 4,500mi since Feb 2023.

Is that the best estimate possible without doing a full drain/charge test via service menu?

"Nominal full pack" is the current battery capacity, not when it was new - that's the same value as each dot measurement in the Tessie capacity chart (and it will fluctuate with every charge.) There's no way to know the original nominal full pack of your battery unless you measured it on day one. Tessie's original capacity is "nominal full pack" on day one for everyone with your car config to give you the closest possible number.

Ideally, "full pack when new" in your screenshot would tell you the right value, but that's a hard-coded value and doesn't represent your individually manufactured real-world battery. More info at SMT: Nominal Full Pack tracking.

 

[AAKEE]

For those that are able to get the the nominal and buffer, perhaps allowing those users to type in the values for now until there is a way via the API could work as a stop gap measure.

I finally got Scan My Tesla installed on my 2023 MYLR and it is showing 78.7kWh for the nominal full pack which differs only slightly from the 78.5kWh that Tessie defaults to, so I corrected that. Looks like that's apples-to-apples (includes buffer) so that's good.

Now Tessie is showing 0.1% degradation, with about 4,500mi since Feb 2023.

The battery pack in your MY LR is marked 82.1 kWh Full Pack when New.
The EPA test of the MY LR 2023 (was actually made on a 2022 as per the test certification), gave an output of 80.7kWh. The MYP (same battery did output 81.05kWh. There are some EPA tests where this battery type did actually deliver 82.1 (82.07kWh).

But as a start, they deliver about 81kWh on cars for the EPA test, which is ”broken in” by use, this 2022 MYLR was driven 4000miles Before the test. A completely new might deliver slightly more.


The 330 miles EPA range set the demand of the delivered capacity to slightly above 79kWh, somewhere around 79.1-79.2kWh. We find the same number on the M3LR with the same pack.

How to set the starting value can be discussed (huhh)….either the marked ”Full Pack When New” or the about 80.7 to 81kWh delivered in the EPA test, or the minimum energy needed to actually make the EPA range the car was sold with.

330 miles EPA range needs about 79.1-79.2kWh, there’s probably someone that have the exact number on that. @AlanSubie4Life maybe?

Any initial capacity below that 79.2 (-ish) will not cover the specified range. The cars normally start with a higher capacity, and the rated miles have a larger energy content when the battery has a higher capacity so the range doesnt go higher than 330.

I can see 79.2, but not lower as the initial capacity, or 80.7-81 or 82.1 KWh.

Inside the Tessie battery meter it should say 79.2 (at least) to cover the range the car was sold with.

Is that the best estimate possible without doing a full drain/charge test via service menu?

The battery test seem to have shown strange results from what I read so in that case, better to believe the nominal full pack value, even if it can be off track sometimes. Or do as I did last summer, charge full and drive to 0% (use Scan my tesla to hit 0% as close as possible), and after checking the SOC a while after the drive you can use the used energy and divide by 0.955 to get the total capacity including the buffer. Do not drive very fast as heat losses will take some “invisible energy” from the equation. 55mph or slower might be good.

 

[AlanSubie4Life]

330 miles EPA range needs about 79.1-79.2kWh, there’s probably someone that have the exact number on that. @AlanSubie4Life maybe?

Not sure whether you are asking for the degradation threshold or not. I think it is about 79kWh for this vehicle based on prior data reports from owners (long time ago now, a search here could find it probably). Though not 100% sure. It’s easy for the vehicle owner to determine though (just need the charging constant value -so rated line, minus 5Wh/mi).

It could be 78.9kWh too. (358/353*77.8kWh).

So I would assume the rated line is at 244Wh/mi (so 239Wh/mi is the actual value).

I think it is not as high as 79.2kWh, though if the rated line is at 245Wh/mi, constant value 240Wh/mi, it is. (Lots of rounding error here makes it impossible to get the tenths place exact, without more careful observation.)

 

[AAKEE]

"Nominal full pack" is the current battery capacity, not when it was new - that's the same value as each dot measurement in the Tessie capacity chart (and it will fluctuate with every charge.) There's no way to know the original nominal full pack of your battery unless you measured it on day one. Tessie's original capacity is "nominal full pack" on day one for everyone with your car config to give you the closest possible number.

Its a good conformity between the real NFP and the usable capacity. Just remember, this is includes the buffer

Ideally, "full pack when new" in your screenshot would tell you the right value, but that's a hard-coded value and doesn't represent your individually manufactured real-world battery. More info at SMT: Nominal Full Pack tracking.

There might be a difference between what’s really possible to draw from a 82.1 kWh pack and the nominal full pack number.
The cars tested for EPA has been used for a while with about 4000miles on the ODO before the tests, and they still deliver about 81kWh.

 

[AAKEE]

Not sure whether you are asking for the degradation threshold or not. I think it is about 79kWh for this vehicle based on prior data reports from owners (long time ago now, a search here could find it probably). Though not 100% sure. It’s easy for the vehicle owner to determine though (just need the charging constant value -so rated line, minus 5Wh/mi).

Yes, the degradation threshold, like when the car shows the EPA range.

Per the SMT numbers from @rwojo (that is rounded on these print screens) we have NFP = 78.7 kWh and 328mi range.

330/328 x 78700 = 79.2kWh

78.7kWh gives 328 miles, which is rounded of corse (both numbers). 78.7 + 2 x 0.24 (240rmi) = 79.2kWh.

It probably could not be close to 78.7, as (the ronded, again) 328 doesnt reach 330 miles.
A closer to full charge would reduce the error magin.

 

[MagnusMako]

What I'd really love is to provide a nice breakdown (like 80 kWh total, 3 kWh buffer, 77 kWh usable). That's the dream. Hopefully Tesla eventually provides a way to see it.

.... Otherwise some people use ScanMyTesla with an OBD scanner to verify the underlying battery pack data.

edit: subtract buffer inclusion

I'd imagine Tesla does provide a way to see it via their Service Subscription using the Diagnostic Software Toolbox 3 but seems unlikely they will ever provide it freely as they don't reveal it in the Service Mode screens either. Kind of scummy to gate that information behind a paywall be honest.

The Ingenext module and app provides readings as well to show the "Beginning of Life Energy" and the "Full nominal kWh".

I used Tessie app back in December and got a reading of 19.4% degradation then did some deep full cycles and used again recently and got a lower reading of 17.8% degradation. Dec 2018 build Model 3 LR DM with Ghost Mod and 83.3k miles.

 

[AAKEE]

I'd imagine Tesla does provide a way to see it via their Service Subscription using the Diagnostic Software Toolbox 3 but seems unlikely they will ever provide it freely as they don't reveal it in the Service Mode screens either. Kind of scummy to gate that information behind a paywall be honest.

The Ingenext module and app provides readings as well to show the "Beginning of Life Energy" and the "Full nominal kWh".

I used Tessie app back in December and got a reading of 19.4% degradation then did some deep full cycles and used again recently and got a lower reading of 17.8% degradation. Dec 2018 build Model 3 LR DM with Ghost Mod and 83.3k miles.

Your initial capacity should say 77.8 kWh.

Seems like Tessie often stucks about the degradation treshold?

The buffer thing is already, since long time, sorted out. There is even not the slightest doubt….

BTW, I would be interrested knowing the following for your car (to test your values in my degradation calculator).

-Whats the normal SOC you charge to?
-End of the day SOC, in average before charging?
-What time do you start the charging?
-Charge every day in general?
-Do you have a garage or park outside?
-Lifetime consumption?
-The climate, live in Texas?

 

[MagnusMako]

Your initial capacity should say 77.8 kWh.

Seems like Tessie often stucks about the degradation treshold?

The buffer thing is already, since long time, sorted out. There is even not the slightest doubt….

BTW, I would be interrested knowing the following for your car (to test your values in my degradation calculator).

-Whats the normal SOC you charge to?
-End of the day SOC, in average before charging?
-What time do you start the charging?
-Charge every day in general?
-Do you have a garage or park outside?
-Lifetime consumption?
-The climate, live in Texas?

I don't see Tessie listing the initial capacity, however it is listed in Ingenext and I attached it to my last post, which yes it shows at 77.8 kWh.

To answer your questions:

-Whats the normal SOC you charge to? 90% every night for many years, more recently only 90% every day or so during the day
-End of the day SOC, in average before charging? It varies. As of 6 months ago, the company I work for opened our new headquarters with free on-site Tesla charging, so I almost always charge at work before leaving at 6 pm. As I am at the office only 3 days of the week - I usually manage to charge to my set 90% before leaving, come home and not charge, then back to the office two days later and charge again. But to give you a realistic answer, I typically am until around 50-60% before I start a charging session for the past 6 months. In the first 3.5 years at a duplex before moving into my own house, I would typically get home around 70-80% then charge to 90% again on a 30A charger.
-What time do you start the charging? Typically at work in the afternoon - around 2 or 3 pm until 6 pm (enough to charge to 90).
-Charge every day in general? First 4 years was mostly every day, The last 6 months it's about every 2 or 3 days.
-Do you have a garage or park outside? Garage charging for home charging the first 4 years. Work charging outside and my normal place to charge in the last 6 months.
-Lifetime consumption? 70,497 mi / 20,877 kWh / 296 Wh/mi
-The climate, live in Texas? Austin, Texas - humid subtropical climate; long hot summers in the 90's and sometimes 100's with mild winters.

 

[AAKEE]

I don't see Tessie listing the initial capacity, however it is listed in Ingenext and I attached it to my last post, which yes it shows at 77.8 kWh.

The capacity in the meter is supposed to show the initial capacity. If it show a too low value, it will show a lower degradation than the real one, thus not helping users to reach out to Tesla at the right moment. Which could mean, you miss the time or miles limit to get a new replacement battery as per the Tessie information on that page in the app.

In the meter = initial capacity
“usable capacity” = present capacity
Degradation= 100-(usable capacity/initial capacity*100)

To answer your questions:

-Whats the normal SOC you charge to? 90% every night for many years, more recently only 90% every week or so.
-End of the day SOC, in average before charging? It varies. As of 6 months ago, the company I work for opened our new headquarters with free on-site Tesla charging, so I almost always charge at work before leaving at 6 pm. As I am at the office only 3 days of the week - I usually manage to charge to my set 90% before leaving, come home and not charge, then back to the office two days later and charge again. But to give you a realistic answer, I typically am until around 50-60% before I start a charging session for the past 6 months. In the first 3.5 years at a duplex before moving into my own house, I would typically get home around 70-80% then charge to 90% again on a 30A charger.
-What time do you start the charging? Typically at work in the afternoon - around 2 or 3 pm until 6 pm (enough to charge to 90).
-Charge every day in general? First 4 years was mostly every day, The last 6 months it's about every 2 or 3 days.
-Do you have a garage or park outside? Garage with 48A charging outlets.
-Lifetime consumption? 70,497 mi / 20,877 kWh / 296 Wh/mi
-The climate, live in Texas? Austin, Texas - humid subtropical climate; long hot summers in the 90's and sometimes 100's with mild winters.

Thank you very much, I apprechiate it. Currently away but I see if I can reach my calculations from here and test your values in my formulas.

 

[MagnusMako]

Certainly. And just to add a bit of information - I definitely don't drive like grandma so I'm not exactly surprised my degradation is on the higher end. I've done at least a dozen drag strip nights in 2019 and 2020 and probably close to a thousand (if not more) launches from a dig or a roll. I usually put down half to full power on the accelerator almost daily.

 

[AlanSubie4Life]

Yes, the degradation threshold, like when the car shows the EPA range.

Per the SMT numbers from @rwojo (that is rounded on these print screens) we have NFP = 78.7 kWh and 328mi range.

330/328 x 78700 = 79.2kWh

78.7kWh gives 328 miles, which is rounded of corse (both numbers). 78.7 + 2 x 0.24 (240rmi) = 79.2kWh.

It probably could not be close to 78.7, as (the ronded, again) 328 doesnt reach 330 miles.
A closer to full charge would reduce the error magin.

As a reminder/cross check, if anyone wants to check it for the Model Y:

Energy screen pic with rated miles also in the picture at a high SOC also allows constant calculation. Taking one with km selected might also provide additional cross check. I think this has been done before here, as I mentioned, a search might find it, or not.

Energy product (proj range * recent efficiency) divided by rated miles at any specific instant gives the constant.

We’ll still be dealing with rounding error of course, which can be used to work out the range of possibilities, maybe.

240Wh/mi constant means 79.035kWh to 79.365kWh. 239Wh/mi constant means 78.7kWh to 79.035kWh. Assuming the constants are round numbers (in Wh/mi) of course, which they might not be (I just don't know for sure though it might be possible to deduce it if you observe very very carefully).

 

[AAKEE]

To answer your questions:

-Whats the normal SOC you charge to? 90% every night for many years, more recently only 90% every day or so during the day
-End of the day SOC, in average before charging? It varies. As of 6 months ago, the company I work for opened our new headquarters with free on-site Tesla charging, so I almost always charge at work before leaving at 6 pm. As I am at the office only 3 days of the week - I usually manage to charge to my set 90% before leaving, come home and not charge, then back to the office two days later and charge again. But to give you a realistic answer, I typically am until around 50-60% before I start a charging session for the past 6 months. In the first 3.5 years at a duplex before moving into my own house, I would typically get home around 70-80% then charge to 90% again on a 30A charger.
-What time do you start the charging? Typically at work in the afternoon - around 2 or 3 pm until 6 pm (enough to charge to 90).
-Charge every day in general? First 4 years was mostly every day, The last 6 months it's about every 2 or 3 days.
-Do you have a garage or park outside? Garage charging for home charging the first 4 years. Work charging outside and my normal place to charge in the last 6 months.
-Lifetime consumption? 70,497 mi / 20,877 kWh / 296 Wh/mi
-The climate, live in Texas? Austin, Texas - humid subtropical climate; long hot summers in the 90's and sometimes 100's with mild winters.

I tried to use the most average values from your description, this is the result:

Initial capacity was set as the 77.8kWh full pack when new.

If we use 75.9 kWh as the initial value, we end up at 62kWh.

 

[MagnusMako]

I tried to use the most average values from your description, this is the result:
View attachment 942944
Initial capacity was set as the 77.8kWh full pack when new.

If we use 75.9 kWh as the initial value, we end up at 62kWh.

Very cool to see, thank you. I hope I can either level off or degrade past 30% before my warranty is up so I can get a battery replacement lol. Guess only time will tell.

 

[AAKEE]

Very cool to see, thank you. I hope I can either level off or degrade past 30% before my warranty is up so I can get a battery replacement lol. Guess only time will tell.

It levels of by the square root of time.

The prognose would be that the calendar aging will be 34% more than today at 8 years age, when the warranty expires. Thats 19-20% or so.
The miles driven, you’re at 70% of the miles for the warranty limit, so the cyclic aging should be at 5% or so when passing the warranty limit.
If you max the warranty by passing 120K at the 8 year day we are looking at about 24-25% or so.

The warranty only guarantee you to have 70% by the 8years/120K miles (is it?).
This means if your battery will degrade too much you get a battery that can make the 70% limit but most probable not a new one.

 

[ran349]

Aye, I agree that lack of smoothness ought to translate into less vehicle efficiency. In my case, I'm typically above 100%. I'm not sure why. I'm certainly not a cautious, slow driver favoring Chill Mode. Quite the contrary... I still debate purchasing the $2K Acceleration Boost upgrade. But I do make extensive, routine use of Regen braking and have brought much of my motorcycle throttle-control philosophy over to the Tesla.


View attachment 938918


View attachment 938919


View attachment 938921




I couldn't agree more on the use of Regen with a pack at even moderate temps. Depending upon how much deceleration I need, I often will release the throttle pedal completely, but although max Regen is spec'd at 85 kWh, I've never seen more than about 50-55 kWh or thereabouts. I'm guessing you'd have to be coming down from a pretty high rate of speed to generate all the Regen the car is capable of.

Anyway, I should say that I LOVE, LOVE, LOVE Regen when the pack is nice and warm. If the pack is even moderately cool, I don't like Regen at all (and will modify my driving style to avoid it).

I am surprised at that chart of efficiency that shows so many cars above 100%. But on your charging page, it shows you have an estimated 416 miles out of a rated 353 miles.
Are you really able to drive 416 miles on a single charge like the chart shows?

 

[Regaj]

I am surprised at that chart of efficiency that shows so many cars above 100%. But on your charging page, it shows you have an estimated 416 miles out of a rated 353 miles.
Are you really able to drive 416 miles on a single charge like the chart shows?

Presumably, yes.

The caveat is that most trips that would go 416 miles would probably involve a lot of high-speed interstate miles. And vehicle efficiency declines at high speeds. I did a 200-mile trip a couple days ago where the speed limit was mostly 70 mph - meaning actual speeds were closer to 80 mph. My Wh/mi on that trip declined to around the lifetime average for my car (currently at 234 Wh/mi after 17,000 miles). Most of my driving (which includes frequent stretches of interstate, but at slightly lower speeds), sees Wh/mi numbers well below that. And my lifetime average continues to decline. I attribute that mostly to ambient temps here in the mid-Atlantic being pretty ideal for an EV right at this moment.

But, yes, the EPA-rated range displayed by the car's BMS has a flip side: beat the efficiency number the EPA extracted from their sample and your car will go further than their's did.

Everyone talks about the inevitable battery degradation that happens with EV's. Not many squint their eyes and wonder how much range one might get if we parcel out those joules stored beneath us judiciously and with great care.