I made a bottom balance. https://www.youtube.com/watch?v=UJx7qL6Eo08https://www.youtube.com/watch?v=o-9LMiZdoNc
DbMandrake and others after replace cells observe a no relevance gain. I´m not an expert but an electric mechanic in Spain "80% electricos" has a lot of experience special with Smart and Citroën C-zero (i-miev) from carsharing companies. Following his information is important reset BMS and BMS history. Are two steps.
Don't believe the display of charge and the new autonomy!!!!!!! . And drive only with the old autonomy. You can drive with the Obd plug in and reading the voltage for more security.
After this, I charged and finally discharged finding the minimum voltage diference between cells. Wait two hours. Drive a few Kms. Wait two hours. Charge maybe only 15-20 min. Wait. Drive. Etc.....Charge a few minutes and you can see with Hobdrive how up the voltage but the "Ah BMS remaining state" up very slow. You can go down the voltage and finally discharge the car with balanced cells. With no charge in display of the car, I started charge. Then, before inject intensitivy , the voltage go very fast to 3.8v. When the display marks 3 steps all change. Out of reserve, start the intensivity. After this is very dificult to balance charge for the BMS.
I use Hobdrive watching BMS state. Min Max voltage Ah remaining etc....
The voltage and charge has a correlation but are not the same. 4.1v maybe is not a full charge for some cells.
The goal is a battery pack balanced not only with full charge, with bottom charge too.
Car Scanner App "can" make a "smoothing voltage" free. But I dind´t use yet.
This is my experience not a recomendation.