Otherwise it asumes the capacity calculation is unreliable and increases the buffer up to 11kWh [% actually]
Great information. Thanks.
Seems to mostly explain what is seen above. Not sure what the meaning of SMT SOC and SOC expected (expected seems to be true SOC) is (it’s been explained to me before but I have forgotten). If I understand correctly (I may not, please correct!): Anyway it seems like an extra 6.5 % was allocated here taking it up to about 11% buffer. That would lead to about 4% displayed SOC.
8.4kWh, 11% of 53kWh is 5.8kWh, so 8.4kWh-5.8kWh = 2.6kWh of (53kWh-5.8kWh) is 5.5%, 2.6kWh of (0.955*53kWh) is 5%. Not sure which of the ways they would calculate the displayed SOC. Close to 4% anyway.
Confusing.
Same calculation but assuming NFP in SMT excludes buffer....
Don’t think you should do this, as discussed. NFP always includes the buffer, but sounds like the estimate can be off on these LFPs at low SOC. Still, you can trust the energy available shown by SMT is the system’s best estimate, even if it is not correct. So: It’s possible the system has less energy than the estimate at low SOC (hence the patches to the buffer on the LFPs), which would mean in reality you may have added more energy than the SMT delta. Which would yield better charging efficiency, perhaps closer to 85-90%.
You could try smaller additions of energy (say 50%), after a quick drive after a charge to 100% (not allowing time for BMS to drift off), and see whether the numbers are more reasonable.
In any case this still supports my claim that no more than 91-92% efficiency is likely possible. I guess one of these days I should check it in my car, though I’d have to just time the charge precisely, since I don’t have a dedicated meter. Also I don’t have SMT so would be multiple error sources.
I guess the SR+ (and RWD) vehicles getting 89% efficiency in EPA docs supports the idea that all vehicles, even the LR, are charged at 32A, 7.7kW, not 48A, for the 89% EPA number. Would be nice if they documented it. So at 48A 11.5kW it would be a bit higher efficiency, maybe 1-2% better. And yes the overnight loss in EPA test could knock 1-2% off these numbers. So maybe 93% best case?