Well, why would you expect more than 4%?
- The individual cells have had a bump of capacity by 4.1% (4.8Ah vs 5.0Ah)
- The total amount of cells remained the same (n=4416)
- 77.8 x 1.041% is exactly 81kWh!
View attachment 653784
View attachment 653783
I was looking after another thing when I found this table.
The cell capacity is not correctly calculated. The voltage will not hold 4.2V during a complete discharge but will drop during the discharge.
The average voltage should be the ”nominal cell voltage”, which shoudl be 3.7V on these cells. If doing a calculation about the energy content in Wh you should use the nominal voltage times the Ah-rating or tested A—value. I think there is some tests on the net showing the old 2170 model 3 cell, marked Wh is 18,5 and marked marked size is 5000mah, but the tests shows real content to be 4800mah or slightly above Which seems to be consistent witht the official Tesla dokuments about the cells.
Marked capacity 18.5Wh for the old 2170 should be a little optimistic. If we use the factor 4.8/5 times 18.5Wh we get 17.76Wh.
4416 x 17.76 = 78.4kWh.
For the new 2170L-cell, if we use 5000mah as the actual capacity we get 3.7x5x4416 = 81,7kWh. To reach the 82.1-mark we need the capacity to be 0,5% larger, 5025mah.
The M3 battery capacity is not as large as it seems by your table. We can see the voltage with low SOCs with SMT and compare it with a discharge curve that the state of charge really is low.
1.6% displayed SOC should be about 6% ”real SOC” according to the common knowledge of 4.5% buffer below 0% dispalyed SOC.
15kW battery power should be quite close to 0.2-0.25C and also close to 1A current. 278V equals 2.9V/cell.
Down is a discharge curve of a tesla 2170 cell. The current draw is 1A, so the Voltage droop should be similar.
If we look at the 2.9V position we see that it is about the knee where the voltage starts to droop quite fast and there is not much energy left.
We can calculate the approximate resting capacity below 2.9V by multiplying the average voltage times the Amp hours. The average voltage could be somewhere in the ball park of 2,85V, and the Amps is 1A, time about 15minutes(= 0.25 hrs). The resting Wh is about 0.71 Ah, or 0.71/17.75 % of the Watt hours, 4%.
As this calculatiuon is not done by exact numbers. The SOC vs voltage is grabbed from a youtube video and might change slightly if another fram was chosen. Its not ”perfect” but I think we clearly can see the similarity between my 4% calculation and the 6% ”real SOC” on the picture above. When the car has shown 0% and is driven until it stops there is virtually no energy left In the cells.
The(my) conclusion is that the marked capacity by Tesla, Full size when new, is the whole capacity without any hidden capacity.
The SMT picture is grabbed from this video by Teslabjörn:
The discharge curve is grabbed from this video: