I will further explain cell balancing as follows and hopefully this will clear up what I described earlier...
There are TWO types of cell balancing. For the sake of discussion I will call them (1) Passive Cell Balancing, and (2) Active Cell Balancing.
Passive Cell Balancing = Cell balancing that takes place naturally as I described previously. This type of cell balancing is completely foreign to most self proclaimed "experts" on lithium batteries since their experience comes from the hobby world (i.e. radio controlled cars, trucks, planes, drones etc.). The cells used by the hobby world are generally of a much lower quality than what is used in our bikes. The cells in our bikes have a VERY tight spec tolerance on both capacity and internal resistance. This is done by screening the cells and only using those that meet these very tight specs. It is because of these very tight tolerances that this passive cell balancing actually works. You can NOT rely on passive cell balancing for cells that are not matched (i.e. capacity and internal resistance).
Active Cell Balancing = Cell balancing that requires the BMS to actively manage the balancing of the cells while the charger is in CV mode and current is below 4 amps in order to get the balance to within a very tight margin (less than 5mV as I stated previously). Doug and others are correct that this only takes place at the very end of the CV charge cycle. As I stated previously, on our bikes it takes place when the current to the pack is less than 4 amps. When most people talk about cell balancing this is what they are talking about. For the charger, all that is required is for the CV voltage to be correctly set such that current is low enough when the pack nears 100% SOC. If the CV voltage is set too high then the charger current will be too high when pack voltage reaches 100% SOC and the BMS will cut off charging without any active cell balancing. If the CV voltage is set too low then active cell balancing never takes place because pack voltage doesn't get high enough to trigger the BMS to start active cell balancing.
I'm certain that Terry and Brandon are very familiar with both passive and active cell balancing and they also know that active cell balancing only takes place at the end of the charge cycle. I feel confident in saying that when they said " don't have to worry about cell balancing not occurring until 100% SOC." what they meant is that due to passive cell balancing the cells will be within "acceptable" balance without charging all the way to 100% and allowing active cell balancing to take place and not that active cell balancing starts at 50% SOC.
mrwilsn is right at every points. Thanks btw for explaining that so well.
Doc
Thanks Doc, it's my pleasure.