Cascade 2 active balancers?

[zzzdgr]

Hello,

I have a motor battery that is 30s. I want to know if it is possible to put 2 active balancers and connect them / cascade them. ie a 16s and a 14s.
I assume it would be possible to put them on the battery independently but is there a way to join them to balance all 30 cells?

thx
Dennis

 

[BentleyJ]

JK-BMS stand alone balancers can be used in the manner you are describing. Check the link below and scroll down to the wiring diagrams. Other brands may have this capability, I'm not familiar enough to say for sure. Wiring diagrams should be available on the internet for NEEY and others.

JK-B2A24S - JK BMS

Product Overviews: Battery Active Equalizer (JK-B2A24S) is a balanced solution for large-capacity series lithium battery packs Management system.The equalizer uses a supercapacitor as a medium to achieve active energy transfer equalization. The equalizer is suitable for 2 to 24 strings of...

www.jkbms.com

 

[Sven77PV]

Is there anybody out there actively using JK-BMS balancers cascaded?
I knew of their capability and build a 64s battery with currently 3 JK balancers. But now I noticed the following:

When the battery pack is being charged or discharged, the voltages of the "cascading cell" differs a lot between the 1st and 2nd (and between 2nd and 3rd) balancer! In fact the last cell of an preceding balancer is physically the same as the first cell of the next.
I used the voltage calibration of all balancers to match the single cell voltages when idle. I also verified the voltage of the cascading cells to match the displayed voltage.
But when charging or discharging (with may 5-15A and 105Ah cells, so only ~0.2C), the voltages differ up to 250mV (the difference increases over the time of charge/discharge)!
Right after stopping the (dis)charge, the cells show nearly the same voltage again.

To examine the problem further, I now switched the balancing off and I will monitor the cells manually to see, if it makes a difference.
If so - what balance trigger voltage is best? I use 30mV, maybe I only have to increase this to avoid the described problem?