I'm using my REC Q BMS with 560 Ah at 48 volts, 32 LiFePO4 battery's total. 100 amp Inverters. 2, 100 amp charge controllers, I've been getting this Cell Voltage differs more than set error. If anyone could recomend any changes to my setting that would be great
It looks like you have a pretty big cell imbalance problem. I see that your balancing ends at 3.58 but you stop charging at 3.53, which is part of the issue.
If it were me I would adjust my setting to something more like:
End of charge 3.58
End of Balance 3.60
Start Balance 3.40
It also looks like what is happening in your setup is that you are trying to balance at too low a voltage, where the cells are basically in their "flat" part of the profile and its very difficult to accurately calculate the cells SoC. By moving it up to 3.4 to 3.45 where the cell profile changes, you dont inadvertantly try to balance a cell that doesnt need to be balanced.
At this point I would break the pack down and do a parallel static balance, but if not possible, I would leave it to top balance for 2-3 days with a small 1-2amp charge. Your BMS may get hot trying to bleed off the cells, so a fan placed over it will help until they come back into balance. You can also try an incandescent light bulb to bleed off the highest few cells. It will take much longer than you think.
Good luck,
@Rick Thanks
Regarding the CELL SETTINGS INSTRUCTIONS if I type RAZL? I get a
2.50000e-1, that means what?
Regarding the Parallel strings box on the settings, I have a 16S2P Bank (32 batteries), Should that box be 0?
That e is the number of digits to offset the decimal, so the e-1 means your RAZL is 0.25 :)
I think you mean you have a 2P16S system with 2 cells first paralleled than those 16 put in series to give you 16 of 560Ah cells at 48V nominal. If you had 2 sets of 1P16S cells each with their own BMS that setting would automatically be set to 2.
Hope that helps
@Rick Thanks for your recomendations, that works. Take a look at my logging is this fairly normal for the differnt resistence, I noticed it can change alot on differnt days
