Daly BMS cannot balance cells even after a Month

[Laurel Katiyo]

So this is my issue, i was a beginner to building diy packs and bought 8 Hithium 280 cells. I need power urgently and used them in series without a bms for about a week but never really drained them. I was charging and discharging using the inverter's built in mppt charge controller, ltr on my daly BMS arrived and i connected it. Since then i have 1 problem. 2 or the cells seem to have deviated a lot from the rest. When charging, one of the other 6 cells will reach 3.65v and charging will stop while those other 2 are still lagging behind at maybe 3.1v or 3.2v and the BMS just stops the charging, and also when discharging those 2 cells that didn't charge to 3.65v will run out of power first and drain to 2.5v and the BMS just shuts down so i end up with 1 cell that is causing the BMS to shut down at 2.5v while other 6 cells will be around 3.35v or 3.4v. So in the end i have a pack that works for only 6 hours and the BMS will turn off the discharge when 6 cells are still clearly over 80% and the BMS itself is saying 87% but can no longer use the pack because 1 cell has run out. Is there any way to counter this. I live in Zimbabwe and diy packs are something that is unknown and i can get a charger for 3.65v to top balance nor an active balancer anytime soon as i have to wait 2 months plus for any order to get here, what can i do to solve this, will connecting all cells in parallel do the trick?

 

[LakeHouse]

what can i do to solve this, will connecting all cells in parallel do the trick?

No, not unless you have a dc power supply to top balance. Just connecting in parallel may make a small improvement, but it won't fix the problem.

Assuming your cells are just out of balance and not permanently damaged:

The longer-term solution: Order an active balancer, or a better BMS with active balancing now. Having this problem solved in two months is better than having it solved never.

In the short term, probably the best you could do without a dc power supply is to manually discharge the highest cells. Leave the BMS connected, and when the battery is near fully charged, connect an individual high cell to a resistive load like an incandescent car light bulb (because they're meant for 12V) for a few minutes. Doesn't matter if the bulb illuminates, it'll be drawing some current, and you should see a voltage drop in that cell on the BMS. Repeat with other high cells.
This will be a slow and user-intensive process, but should help.

 

[robbob2112]

This..... full charge.... let it rest a few hours... then I used a 100w30ohm resistor across the runner cell to bring it down to the other cell voltages....afterwards it stays pretty much in sync with use,

But getting a better bms with 2a active balancing is the best choice

Battery hookup has some 8s 100a JBD bms or aliexpress once you lookup and know the exact model... then verify when ordering....or order straight from JBD....

Note - JK, ANT, and some others have it as well but I favor the JBD for my 8s 24v batteries

 

[Skypower]

This..... full charge.... let it rest a few hours... then I used a 100w30ohm resistor across the runner cell to bring it down to the other cell voltages....afterwards it stays pretty much in sync with use,

But getting a better bms with 2a active balancing is the best choice

Battery hookup has some 8s 100a JBD bms or aliexpress once you lookup and know the exact model... then verify when ordering....or order straight from JBD....

Note - JK, ANT, and some others have it as well but I favor the JBD for my 8s 24v batteries

Just looked at the JBD offerings. If I had to start anew, I seriously consider them plus a EnerKey 4amp balancer.