2018 Tesla model 3 performance range drop

[AlanSubie4Life]

Soon 6 years age?

Standard 25C average temp,

5.5% first year x square root (6) = 13.5% (+ a little cyclic degradation).

Yeah most likely more like 5.3 years old, hard to know. And that is just 12.7%.

Anyway I feel like low 270s is slightly low.

I have a car in the mid to upper 280s near identical age and I don’t feel mine is “really good.”

Then there’s @KenC ‘s Legend of the North which is from 2019 and is still showing around 310 miles (just 3%).

So I feel like it is probably average, on the high side. Of course, we have no idea how it was kept - probably somewhat hot and high. Which would make it fit the formula exactly. Presumably it DOES fit the formula.

 

[AAKEE]

Yeah most likely more like 5.3 years old, hard to know. And that is just 12.7%.

Anyway I feel like low 270s is slightly low.

I have a car in the mid to upper 280s near identical age and I don’t feel mine is “really good.”

Then there’s @KenC ‘s Legend of the North which is from 2019 and is still showing around 310 miles (just 3%).

So I feel like it is probably average, on the high side. Of course, we have no idea how it was kept - probably somewhat hot and high. Which would make it fit the formula exactly. Presumably it DOES fit the formula.

Yes, the 5.5% X square rt (6) was just average 25C taken as an example.

As most people charge or did charge 70-90% the 5.5% first year is about constant so only the average temp that really changes it.

5.3 yrs, 65k mi, 80% charging and end of day 60% at a 25C average temp gives this end result:

If we knew the former owner and could check things up more precise we probably could get a very good match, but this isnt that far away either. I did set the charging to start at dinner time in the picture above.
Lowering the charging to 70% and 50% at end of the day + charging in the morning set it like this:
So the take-away for the OP is that the battery probably is spot on what to expect. As we do not know exactly how the earlier owners did charge we can not make a 100% exact calculation but we can see that it is in the spann of the normal.

 

[AAKEE]

@randall_s : I think you might appreciate this thread where we are discussing real life degradation with the help of research data.

 

[N54TT]

Just wanted to add some data points. My 2018 performance 3 charged to 279@90% and 310 at 100% when I first got it. I’m at 73.6k miles and it’s now 296@100%. Up until Tesla lowered the daily charge limit to 80% I charged to 90% even though my daily commute is only 45-50 miles……just because I wanted max power .

 

[AlanSubie4Life]

@randall_s : I think you might appreciate this thread where we are discussing real life degradation with the help of research data.

Try November 2018, 60k, first three years 80% most of the time. Remaining time 50%. Starting ~78kWh. Call it 20C average (not sure exactly).

 

[AAKEE]

Try November 2018, 60k, first three years 80% most of the time. Remaining time 50%. Starting ~78kWh. Call it 20C average (not sure exactly).

How many miles today?
Time when starting the charge?
End of day SOC?
Garage?
20C ambient avg, so ~25C avg battery temp?

 

[AAKEE]

Try November 2018, 60k, first three years 80% most of the time. Remaining time 50%. Starting ~78kWh. Call it 20C average (not sure exactly).

25C cell temp
Guessing -> 80K km (50K mi) ?
10.5% calendar aging + 1.5% cyclic.
68.6 remaining out of 68

 

[AlanSubie4Life]

25C cell temp
Guessing -> 80K km (50K mi) ?
10.5% calendar aging + 1.5% cyclic.
68.6 remaining out of 68

Sorry. 60k MILES (isn't this the only correct unit of distance?)

Started charge early in day for first 1.5 years. End of day SOC 75%.
Subsequent, from March 2020 to whenever you converted me to 55% (can't remember but call it November 2021), basically was at 70-80% all the time.
No idea ambient battery temp. 25C seems too high (not a lot of driving). I'd say 23C.
Stored in garage. No sun, basically ever, even at work.

For 55%, I am at typically 45% until I charge, at night, starting at midnight.

 

[AAKEE]

Try November 2018, 60k, first three years 80% most of the time. Remaining time 50%. Starting ~78kWh. Call it 20C average (not sure exactly).

Guessing -> 80K km (50K mi) ?

Sorry. 60k MILES (isn't this the only correct unit of distance?)

Oh, missed that.

From what I hear blindness hits the eyes first? I might be there soon

The only correct unit of distance must be one quarter of a mile?

Started charge early in day for first 1.5 years. End of day SOC 75%.
Subsequent, from March 2020 to whenever you converted me to 55% (can't remember but call it November 2021), basically was at 70-80% all the time.
No idea ambient battery temp. 25C seems too high (not a lot of driving). I'd say 23C.
Stored in garage. No sun, basically ever, even at work.

For 55%, I am at typically 45% until I charge, at night, starting at midnight.

Here's what the formulas say. The formulas was not made to use different SOC like your strategy change, but I used the first 36 months as per the description and then added the rest of the time at 55%-45%.

Adjusted to 20C cell temp as the annual avg seem to be around 18C (?) and small charging sessions + not much driving cause the cell temp to be close to the ambient)

After 36 months charging to 80% with 70% end of the day SOC, and early charging:

I guess yo might rememeber the range from that time and can convert it to capacity.


Here what i get as todays capacity.

Remember that these formulas can not be better then the precision in the input so we should expect them to show the approximate remaining capacity and not to hit the exact number.
In this case I guess we have precision enought to hit within 1kWh or so. The average cell temp will not make a big change but if the change from daily 80-70% to 55-45% is shifted 6 months, we get a bigger difference, as this cut the degradation in half.

Do you have a recent full charge to compare with ? (i know the energy graph tell us that as well)

 

[AAKEE]

Here what i get as todays capacity.
View attachment 1015153

Just remembered the recovery effect from low SOC cycling and calendar aging (from when you went from daily 80-70% to 55-45%)
While the research reports mention it, I have no real data on how much to expect.
But you possibly find your battery slighlty better than the above, and if you do - its probably the recovery effect.

Its seen here as calendar aging lower that it should have been below 55%.
We would expect it to be ~ half of the 70-80% calendar aging but it is only about 30% here.
The reason (my own conclusion, not the researchers) is that the cells came from a real model S about six months old I think, probably charged daily somewhere between 70-90% (right ?)

When they put the cells for calendar aging at low SOC, some of the lost capacity was recovered and therefore the low SOC calendar aging came out better than it should have dome with brand new cells.

 

[AlanSubie4Life]

In this case I guess we have precision enought to hit within 1kWh or so. The average cell temp will not make a big change but if the change from daily 80-70% to 55-45% is shifted 6 months, we get a bigger difference, as this cut the degradation in half.

Do you have a recent full charge to compare with ? (i know the energy graph tell us that as well)

In Feb 2021 based on the sticky you can see I was at 71kWh. 290 miles.

I can only check at 51% right now but that calculates to 71kWh.

I think actually it is a bit below 290, though, and I have seen more like a bit over 285 miles, 70kWh, at my last actual full charge.

 

[ran349]

In Feb 2021 based on the sticky you can see I was at 71kWh. 290 miles.

I can only check at 51% right now but that calculates to 71kWh.

I think actually it is a bit below 290, though, and I have seen more like a bit over 285 miles, 70kWh, at my last actual full charge.

That's less than 2% degradation in 3 years! Are you trying to challenge @KenC?

 

[AlanSubie4Life]

That's less than 2% degradation in 3 years! Are you trying to challenge @KenC?

It really slows down.

What is not clear to me is if you can be super careful initially for first few years and then abuse the battery and be way better off.

So for example do the opposite of what I did - would I be at 74-75kWh?

Doesn’t make much sense physically with the SEI but maybe the protective layer is created and stabilizes?

Perhaps @AAKEE could explain the SEI structure at the anode and why it might permanently suck up less of the cyclable lithium or whatever if treated and created carefully.

 

[AAKEE]

It really slows down.

What is not clear to me is if you can be super careful initially for first few years and then abuse the battery and be way better off.

No, more like that the thicker the SEI layer gets the more it “protects” slows down the build up/degradation. (But it costs capacity and there’s a risk of cracks in the layer).

For your calc, I first used the 36 months with high SOC and got a capacity loss a per the first picture. Then I found the appropriate amount of months that would have caused the same amount of calendar aging but with 55-45% SOC. Then I added the rest of the 53 months(27) and the result was the calendar aging at present time for your car. (It has been a good match earlier, and it makes the logical sence from a SEI perspective).

So for example do the opposite of what I did - would I be at 74-75kWh?

Doesn’t make much sense physically with the SEI but maybe the protective layer is created and stabilizes?

The SEI layer first build up is a part of the cycling process at the factory.

I would say that the rate of calendar aging (at a certain SOC and temp) is depending on the thickness of the SEI. Which in turn is proportional to the degradation.