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250000 miles on a 90D

amund7

Former Vendor
May 8, 2015
316
422
Norway
Is the difference between 'capacity when new' and 'nominal full' when new the brick reserve ?
No, that's degradation. Well actually, it's degradation + 'settling' of a new battery. According to BatteryUniversity.com, I think that's where I read it - a new battery has MORE capacity than it's 'rated' capacity, and it will settle down to rated during the first charge cycles. The problem here is, we don't know the 'rated' capacity, and the 'degradation' I calculated in the app from this will show too much degradation. We should have known what the 'settling' was, or have a reading that is the 'rated capacity', then we could calculate degradation correctly.
 

amund7

Former Vendor
May 8, 2015
316
422
Norway
Thanks for chiming in!

I appreciate the graph, and it makes sense. At least for me, the disconnect occurs when I try to correlate SMT with the 'miles remaining' meter on the car's display. E.g, my Model 3 LR has a rated miles consumption of 237 Wh/mile hardwired. When I charge to full I see 308 miles of range which corresponds to 308*0.237 = 73 kWh **

So when the car is fully charged, the buffer is included in the rated miles calculation
Once I have depleted the battery charge to 0 rated miles remaining, a buffer of 73*0.045/0.237 miles remain in the battery that are usable (with the caveats you mentioned.)

I realize that your are not responsible for Tesla. Perhaps the confusion here is that 'usable' in SMT is not always the same as 'rated miles' on the screen display.


**Yes, you used my car for your graph example ;)

Not sure I understand where you're going with this? Why don't you look at 'Usable remaining' for your calculation, then you don't have to worry about the buffer. The car will show 0 miles when usable remaining is 0. And then probably you will calculate a different Wh/mile that fits the 'Usable' - or where do you get that number from?

I think someone has said the range numbers, if plotted throughout the SOC range and against SOC, has a kink at about 20%, but I haven't really studied this. At least I have confirmed from several people that usable = 0 = SOC = 0 = range = 0, and I mean when comparing both SMT numbers and in-car display numbers. They may be off by a fraction, but that's just because the car doesn't show fractions and might have some roundoff logic in the displays.

The screenshot is from my own Ipad Mini I use for testing against my car.
 

SageBrush

REJECT Fascism
May 7, 2015
12,789
17,091
New Mexico
No, that's degradation. Well actually, it's degradation + 'settling' of a new battery. According to BatteryUniversity.com, I think that's where I read it - a new battery has MORE capacity than it's 'rated' capacity, and it will settle down to rated during the first charge cycles. The problem here is, we don't know the 'rated' capacity, and the 'degradation' I calculated in the app from this will show too much degradation. We should have known what the 'settling' was, or have a reading that is the 'rated capacity', then we could calculate degradation correctly.

OK. Where is the brick reserve amount in these calcs ?
 

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