Very few BMS do a good job balancing,
unless the pack is composed of all new well-matched cells
which of course is best.
Once a lot of balancing is needed, it can take **many days** of
using a charge source to hold them over the start-balancing voltage
to achieve a balanced set
because the balancing (bleeding) current is so low.
But BMS is only one way out of many to accomplish balancing.
Selection of matching cells and manual top balancing should happen long before assembling and wiring up the pack for bulk charging.
Balancing chargers and/or adjustable power supplies are ideally available to do it right.
Once assembled in normal cycling, if the cells quickly get out of balance,
in other words, working with a sub-par set of aging or poorly matched cells,
then higher-current balancing gear that can be adjusted to start at lower voltages is required.
