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The battery management will neither charge the batteries to a real 100% or let you discharge them to 0%. Some of the energy going into the car will be used for heat management, and if really cold out, maybe heating. The ac-dc conversion is only about 95% efficient at 240vac inputs (less efficient with 120vac input). The battery management might start the charge slow if the batteries are cold, and will be slow if they are hot, and will slow as the charge gets near the top. It may not slow down that much as on some other vehicles because of the fairly large 'reserve' BMWUSA keeps. AT some point, and it may not happen each charge, the logic will compare the voltages of each module and might try to balance the cells, and that can take some time, otherwise, it's just dumping power into them in parallel.
You'll always be putting more energy into the vehicle than actually gets stored in the batteries because of the inefficiencies involved. Mostly, that is expressed as heat, and that can require cooling, which uses more energy from the EVSE that doesn't go into the batteries. The energy from the EVSE is limited to 16A, so if your nominal voltage is lower, say in Europe where it might be 220 versus 240 in the USA (mine typically is 247), then that could limit the actual amount of energy. If you're in a commercial location, you might only be getting 208-vac in the USA, and that at 16A is only 3328W, so you won't be maximizing your charge capacity (many commercial charge points use 208, not 240 vac in the USA). The EVSE announces to the vehicle the maximum number of AMPS it can pull, the vehicle will then limit the maximum number of WATTS it will consume based on that announced amperage and the supplied voltage.
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