[DanielHB]

You can't really mix different types of cells together in the same pack. Even cells with the same manufacturer and chemistry can be problematic to mix if they are at different wear levels (or even from different batches from the same factory).

This is only practical if you reuse the whole pack, or at least the modules. And for that to work well you also need a lot of complex software to keep the packs working well with each other (like balancing power levels between the packs).

BMS software is no joke, it is already hard and complex enough when using brand new battery packs and cells of the same chemistry and manufacturer and wear level. Any kind of mixing massively increases the complexity and safety concerns.

[Xemplolo]

So they already come with a BMS.

Create a MetaBMS. The BMS of the cell pack doesn't care if a car requests energy between 0 and max and a BMS doesn't care either if it gets 0-100 kWh.

My car can easily charge from a household plug up to fast charger. My car consumes very random amounts of energy while i drive.