alohart wrote: ↑Fri Jan 14, 2022 7:54 pm
No EV manufacturer would allow its battery pack to charge to its absolute maximum voltage unless it supports limiting the top charge level when charging (e.g., Tesla). To do so would result in cell degradation that would make warranty replacement of many battery packs likely. The BMS limits the top charge level on all i3 battery packs.
Of course there must be a maximum voltage limit and it depends on the chemistry. The question here was, if the i3 also leaves some buffer at the top. As you can see from the discussion, the i3 charges the batteries up to the maximum voltage given in the battery specs from Samsung SDI. So they are not overcharged but for me it means, there is also no buffer left on the top end of the voltage range. This is stress for the battery and especially when it is left in this state over longer periods, this is not good for LiIon cells. The whole "buffer" seems to be left only at the lower end of the voltage range.
So this means, the strategy to charge only up to 80% or 90% (as long as you do not plan a longer trip) will be more gentle and it is a pity that BMW never added a feature to set this as the charging target, although their hardware provides all what would be required.