Reason not to keep active balancing always on?

[kissa2]

I have a JK bms with active balancing and today I experienced for the first time low cell voltage protection kicking in. Checking the battery status I noticed one cell was significantly lower than other three cells. My shunt said there should have been over 11% of battery capacity left in m 304ah lifepo4 battery bank. (The lowest cell voltage was 2.7V and other three were above 3.06V)

I realised I could still pull some power of the battery in its current state after activating cell balancing to raise the lowest cell voltage. I'm using someone's recommended settings for my bms from this forum and cell balancing is set to start at 3.3V. I'm wondering why is it recommended (or is it?) to use cell balancing only at higher voltages. Wouldn't it be useful also to enable cell balancing at lower voltages or all the time to pull more power out of my battery bank?

 

[sunshine_eggo]

Disagree with the 3.3V recommendation. that's too low. Balancing is only productive in the upper leg of the voltage curve - above 3.40V.

Balance is not about voltage. It's about state of charge. The voltage curve is so flat in the 3.1-3.4V range that voltage does not correlate to balance. Above 3.40V and voltage correlates with balance.

There is no harm in leaving an active balancer enabled all the time provided it only operates above 3.40V/cell

 

[Bob B]

I have a JK bms with active balancing and today I experienced for the first time low cell voltage protection kicking in. Checking the battery status I noticed one cell was significantly lower than other three cells. My shunt said there should have been over 11% of battery capacity left in m 304ah lifepo4 battery bank. (The lowest cell voltage was 2.7V and other three were above 3.06V)

I realised I could still pull some power of the battery in its current state after activating cell balancing to raise the lowest cell voltage. I'm using someone's recommended settings for my bms from this forum and cell balancing is set to start at 3.3V. I'm wondering why is it recommended (or is it?) to use cell balancing only at higher voltages. Wouldn't it be useful also to enable cell balancing at lower voltages or all the time to pull more power out of my battery bank?

The key thing I see here is .... for the first time.

Best to balance as sunshine-eggo recommended.

 

[MisterSandals]

The lowest cell voltage was 2.7V and other three were above 3.06V)

Even at 3.06V, the cells are less than 10% SoC. You got about 90-95% out of your battery before your BMS stepped in. This is not too shabby!

 

[Captain Hook]

Even at 3.06V, the cells are less than 10% SoC. You got about 90-95% out of your battery before your BMS stepped in. This is not too shabby!

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So am I correct with this: new aolithium battery cell factory settings for 100% capacity was 3.38. This gave a resting voltage of 13.3.5. After charging i noticed cell3 seemed a bit lower 3.32.So I raised 100% to 3.475 (arbitrary number). Charged it and achieved the cell voltage 3.475 - 13.6 then watched cell #3 during balancing pull the other cells down to 3.35 and voltage to 13.35.
So aolithium set the voltage to coincide with that weaker cell?
So that cell is less capacity? If so how much less at 3.35? What is the change in overall capacity?