Battery Degradation question

[AlanSubie4Life]

Finally charged my car (2023 M3LR dual motor) to 100%. Still showing the same 77.8kWh and ~333mi rated range. Wonder if any other owner sees the same

View attachment 973912

Well, that actually says 332, rather than 333, which suggests you are slightly below the degradation threshold. Did you see it switch to 333rmi at some point after it charged for a while?

It's quite possible that after a while it went to 333, I'm just asking for clarification. Basically there is a huge range of energies (above about 77.8kWh) which would display as 333 rated miles at 100% in the vehicle (these are energies that exceed the degradation threshold). But as soon as you see 332 rated miles and it won't budge up to 333, that means potentially that there has actually been capacity loss below the degradation threshold, and for example the degradation threshold might actually be closer to 78kWh (so 332/333*78kWh = 77.8kWh).

The constant still appears to be 234Wh/rmi (we have better accuracy on that now, 243Wh/mi*320mi/332rmi = 234.2Wh/rmi), and the rated miles for the vehicle at max was 333rmi (known from EPA sticker), so technically it is likely the degradation threshold is 234Wh/mi*333rmi = 77.9kWh.

So perhaps you are slightly below that now. If you showed 333rmi, and the energy screen showed more energy as well, concurrently (it should), then you aren't, though.

Of course, this is all just an estimate and as @AAKEE mentioned, this estimate can get adjusted up and down. And it may take some time. Long term, it will of course only go down.

 

[Kelculate]

Well, that actually says 332, rather than 333, which suggests you are slightly below the degradation threshold. Did you see it switch to 333rmi at some point after it charged for a while?

It's quite possible that after a while it went to 333, I'm just asking for clarification. Basically there is a huge range of energies (above about 77.8kWh) which would display as 333 rated miles at 100% in the vehicle (these are energies that exceed the degradation threshold). But as soon as you see 332 rated miles and it won't budge up to 333, that means potentially that there has actually been capacity loss below the degradation threshold, and for example the degradation threshold might actually be closer to 78kWh (so 332/333*78kWh = 77.8kWh).

The constant still appears to be 234Wh/rmi (we have better accuracy on that now, 243Wh/mi*320mi/332rmi = 234.2Wh/rmi), and the rated miles for the vehicle at max was 333rmi (known from EPA sticker), so technically it is likely the degradation threshold is 234Wh/mi*333rmi = 77.9kWh.

So perhaps you are slightly below that now. If you showed 333rmi, and the energy screen showed more energy as well, concurrently (it should), then you aren't, though.

Of course, this is all just an estimate and as @AAKEE mentioned, this estimate can get adjusted up and down. And it may take some time. Long term, it will of course only go down.

Thanks for the explanation. I remember it was at 332mi even at 99% (I was sitting inside using a supercharger), and I was a bit surprised it was not 333 when it reached 100%. But maybe as you said, somehow the battery already suffered a loss from 78 to 77.8. I am not sure I would want to charge to 100% again just to confirm my car can’t reach 333, given how high SoC doesn’t help with degradation, and my battery might have already degraded slightly. Will update the thread again when I do another 100% charge. Thanks

 

[AlanSubie4Life]

Thanks for the explanation. I remember it was at 332mi even at 99% (I was sitting inside using a supercharger), and I was a bit surprised it was not 333 when it reached 100%. But maybe as you said, somehow the battery already suffered a loss from 78 to 77.8. I am not sure I would want to charge to 100% again just to confirm my car can’t reach 333, given how high SoC doesn’t help with degradation, and my battery might have already degraded slightly. Will update the thread again when I do another 100% charge. Thanks

In any case, you are probably close to max (we’d need another 333-mile owner of a brand-new vehicle to do the same to compare and confirm).

It’s possible that for this vehicle they leave very little excess capacity above the degradation threshold. On some vehicles they leave a lot of excess, while on others, typical starting capacity and the threshold are very close.

And we know that the degradation threshold is right around 77.9kWh, as explained above. And we know you are close to it. That much is very clear from your captures.

So perhaps you have no significant capacity loss yet.

Again, only way to really know what the typical starting point is is to get data from other vehicles (and ideally get SMT data on one of these vehicles: it would give info on “Full Pack When New” and how much the NFP exceeds the threshold typically, though there are (difficult/annoying) ways to determine the new NFP value without SMT).

 

[Kelculate]

Not sure if it is proof that my car’s battery improved. Today it showed 333mi at 100%. But quickly dropped that to 332mi as soon as I left the supercharger mall and onto the main road.

 

[AlanSubie4Life]

Not sure if it is proof that my car’s battery improved. Today it showed 333mi at 100%. But quickly dropped that to 332mi as soon as I left the supercharger mall and onto the main road.

View attachment 974560

That gives 77.9kWh (129Wh/mi*604mi) so a tiny step up.

But shows that degradation threshold is at least ~77.9kWh as expected . (It should be 234Wh/rmi * 333rmi = 77.9kWh based on your previous captures, as explained, so we should not see values on the energy screen exceeding that approximate value.)