eMark said:
It's not a difficult question. If it applies to a $15 BMS then it possibly applies to most all BMSs unless one is defective from factory.
Is the following claim bogus or true?
…
Do you know of any inexpensive BMSs like this $15 BMS capable of such a bold claim as underlined?
I do not see anything underlined.
Yes it is not a straightforward issue, only an "easy question" if you have all the required data, which requires more knowledge about how balancing works than it appears you possess. Without those data, the question is not just hard, but impossible to give a simple answer, much less in the binary Y/N you seem to expect.
**Any** balancing BMS can balance a pack **eventually**, if the Ah capacity per group (or cell) is not "too great" and the V delta is not "too high".
Its balancing-related **specs** are what determines the level of effectiveness **for a given context**, assuming they are accurate. Which is why I asked you, please give us the specs of the BMS you are curious about.
A balancing current rate of 2A (or even higher!) will be quicker, or handle a bigger delta and/or be suited for a higher capacity bank
better than the usual sub-amp rate.
One that has (or lets you adjust to) a lower start-balance V setpoint, say 3.9 for li-ion cells,
will have longer to get the job done **within** your usual desired charge profile.
While one with **both** a low Bcurrent **and** a late (say 4.15V) start-balance point, requires a too-harmful AHT, maybe even days, and certainly should not be selected for a large pack, nor one where the V delta gets too high.
Some BMS can be balancing all the time, which I think would be silly,
but that also means they can balance **at any voltage/SoC**, so such a BMS could even be used for middle- or bottom-balancing if that is your preference,
if using "active" capacitance or shunt-method balancing rather than bleeding-resistance method, does not need to be while charging,
just turn the balancing on when at rest at your desired balancing-point SoC, and let it complete however long that takes.
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As for "green lights" the meaning of that would vary by charger, there are dozens of possibilities for how a charger determines "battery Full", and really that should also be adjustable.
The "how long" question has the same answer as "is a piece of string", depends on the four variables discussed above.
Note also that the "finish balance" Vdelta setpoint can be a high vs low delta, and that would have a big impact, and should (of course) be adjustable as well.