Picture has 6 batteries of 8s2p.
(Battery" actually refers to identical components arrayed and working in concert, eg artillery battery)
These 6 batteries are then paralleled using the bare "parallel" wires.
The balance connector is connected to the ends of the parallel wires, 5 on top (shown) and 4 underneath (hidden)
Cells with white discs are Positive - bare w/red ring Negative.
Pairs of cells were pulled from battery packs, left connected with the handy extension "tab" for connecting in series.
Many want to separate every cell, test, then reassemble.
I test in pairs, sometimes in 3's and most recently in 4's with the 10,400mAh packs for latest project.
If pairs etc. are substandard I will separate, hoping for 1, or some, good cells.
I strive for banks of equal capacity, rather than cells of equal capacity.
After these ... hmmm ... 7 years of Lithium pack building ...
One of the surprising things I noticed is that Lithium cells tend to deteriorate at a reliable percentage rate rather than at a capacity rate.
eg Same brand 80% capacity cell paralleled with a 40% capacity cell, tend to diminish in capacity at the same rate. 80% to 40% and 40% to 20%, rather than 80% to 40% and 40% to 0%.
This is reasonable, when you take into account that the weaker cell is charged and discharged at the same residual C rate as the better.
In series, by comparison, the weaker cell would be discharging twice as fast at double the residual C rate, and might deteriorate at 4x the rate as the stronger cell.
Oh! C rate should be calculated at present, rather than original, capacity!
So, after removing self-discharging cells (the bane of any pack builder) I build banks of equal capacity, resting assured of an stable and equal deterioration.
While I do not! use a BMS I do employ a bank level low voltage meter-alarm. <$5.
I bulk charge ... rather than balance charge = no need!
After removing self-discharging cells and having banks of equal capacity, (= equal future deterioration), banks remain balanced. (other than due to physical damage eg broken solder connections!)
I do monitor bank voltage at "full" and "empty".
Any variance indicates a problem and is hunted down!
Sorry! I do not use a BMS
... corrected above.