None of us knows for certain. It could be that the Batt. Kapa. max value, which is calculated, could have been calibrated to more accurately display the usable capacity.opossum wrote: ↑Sat Dec 14, 2019 8:24 pmThe other odd thing you'll see is that after we got the car back (they did a software update and battery test), the max kappa value mysteriously increased from 13.7 to 14.9 and we are seeing a slight increase in range. Did they just 'give' us a sliver of the reserved battery capacity to delay a warranty claim?
Or BMW mechanics might be able to increase the usable capacity of the battery pack by reducing the unusable capacity which is ~13% for a 60 Ah battery pack when new (total capacity - usable capacity / total capacity, or 21.6 kWh - 18.8 kWh / 21.6 kWh = 13%). If this is happening, very few battery packs will be replaced under warranty because the BMW dealer capacity test could be rigged to keep the usable capacity above the 70% warranty level unless the actual capacity drops by more than 30% + 13% = 43%.
We know that the usable capacity can be increased using an older version of BMW's proprietary maintenance software. This capability was removed in recent versions, but is it available in some other maintenance software that BMW mechanics currently use? Or is the battery management system (BMS) running in every i3 capable of automatically decreasing the usable capacity to decelerate the battery cell degradation rate? I don't think we know.
It seems that significant loss of actual range as opposed to predicted range is limited to 60 Ah battery packs, at least for now. If true, is this due to improved battery cell chemistry in 94 Ah and 120 Ah battery cells? Or is it due to the 60 Ah BMS being the only BMS that can reduce the usable capacity because 60 Ah battery packs are most likely to suffer capacity degradation greater than the 30% warranty limit?