Acceptable voltage deviation of Lifepo4 cells while charging

[BabyRaccoon]

Hi i'm using 8s 200AH Lishen Lifepo4 cells and i have top balanced all the cells. I set the bulk charging limit to 27.4 V and float charging voltage to 27V. While charging the cells , when the cell voltage reaches to 3.42V the deviation voltage between the cells began to rise rapidly,at a point it reaches to 320mv. Even though the bms (Daly Smart BMS) start to balance the cells, the deviation keeps on going high so i stopped the charging. what is the acceptable voltage deviation between the cells while charging ?

 

[sunshine_eggo]

Results like that indicate (order of likelihood):

1) you did not effectively top balance your battery.
2) You have an issue with your connections/sensing leads/something.
3) You have a BMS malfunction.

Balancing current of most BMS is very very small, so it's only useful in maintaining well balanced cells - not in compensating for poor quality cells or a bad balance.

Recommend you use your power supply to hit each of cells from low voltage to high voltage until they read 3.65V.

A well balanced battery at full charge will have a very small deviation.