question

Hi @Matthias Pallhuber

Probably a thing that has to do with internal balancing algorithm.

See if it's any change if you try to keep a pack voltage of 56V (3.5/cell) and start balancing from 3.36V per cell?

These voltages are from Pylontech experience/settings.

Alex

Most probably cell voltage measurement error. Every cell voltage is calculated by the BMS based on another voltage value in the battery, heck it could even be the BMS temperature that's playing a role here in deciphering the exact voltage of a cell. You're into too-much micro-management here, imho.

@Matthias Pallhuber I seem to reach an optimum of balance after 15 minutes of 100% reached.. Its always the same 6 cells which are drifting down in the lower voltage block.

I have 4 winston cells and see the same thing when the charge current bottoms out. I never really looked into this and have just accepted that some cells have slightly different "full" charge voltage. Or perhaps more likely that the active balancer (deligreen) is a bit different at the top cells vs the bottom ones. Cells within 10mV at the start of absorp, going up to within 30mV at the end of absorp at 20 mins, 3% tail current.

Given you have noticed that optimal cell balance is about 15 mins into absorp, and around the same time the charge current bottoms out, it would be safe to suggest that the absorp period can be reduced down to 15-30 minutes.

Additional thoughts. Do check the cell voltages at both the cell and at the balance leads at the BMS.

The can socket on both devices.

Kind regards,

Jacco

https://www.victronenergy.com/live/battery_compatibility:can-bus_bms-cable#introduction

Did you top balance the cells?

If it is always the same six, open your pack swap some of them over in position and go again.

Torque and assembly are pretty important.

They show like a 0.02v difference in the beginning of the graph so not bad. The graph scaling makes it worse. Is probably related to the balance trigger between them assuming you have active balancing? (Also settable on JK.)