How safe is adding an active balancing board?

[Jan-Erik-86]

As thew title say, I'm curious about the safety of adding an active balancing board.

As my 12p 13s pack (one 7P and one 6P in parallel) is a mix of used cells it will naturally run out of balance quicker then a pack with identical cells. In the beginning with a 26A controller there was no problems, and after upgrading to a 36A controller there was still not much issues - but after I've shunt modded the controller to 50A I've started to notice it needs balancing more often then before.

The problem is my only way of balancing now it to fully charge the pack as my BMS won't start bleeding cells until 4.2±0.025V, and so I'd prefer not doing this more often then needed. Also, since bleed current is very low, it takes forever to balance.

As active balancing boards does not appear too expensive for a 13-14S battery, I was wondering if this would be a good idea, as i could then have a balanced pack even when charged to only 70-80%, but there was this one thing crossed my mind - how safe is it if a cell should fail and gradually develop an internal short?
Normally when this occur one would quickly notice it as one parallel group would drop in voltage relatively fast compared to the other groups, but with an active balancing board balancing with over 1A, don't we just hide the problem until the cell is so damaged that it draws over 1A in self discharge?

An active balancing board with Bluetooth app that you can use to monitor and turn balancing on and off would solve this problem, however it would be a bit on the expensive side for my budget, and so I've been looking into cheaper alternatives which are constantly on when there is enough voltage difference between the groups.

 

[jonyjoe303]

I been using active balancers going on 2 years, they balance at 6 amps. If a cell develop a short, you wouldn't really notice with or without active balancers.

You can use voltage alarms that will sound an alarm if the voltage between 2 or more cells gets too high. The advantages of having balancers outweighs the disadvantages especially on a battery with balancing issues.

I bought the 4s version of the balancers on your link, and they didnt work. I left connected for 8 hours and one light was blinking but didnt do anything to the balancing. Maybe I got a bad one, but I have no confidence they would work plus they are very small, I don't think they balance at the rate they claim.

If I were you, I research more before buying a active balancer, the cheap ones might not be up to the job.

 

[vreppeto]

I have one of the 5.5a capacitive balance boards https://www.aliexpress.com/item/1A-...122.html?spm=a2g0s.9042311.0.0.27424c4do16ZHS. I m wondering if it is safe to run it in parallel with a cheap chinese bluetooth bms. https://www.aliexpress.com/item/-/33062359787.html?spm=a2g0s.8937460.0.0.9c642e0eiTtu0h
It scared me when AI first triedto connect both units at once because there was a large spark. It makes sense that the should be safe to use together in my mind. I cannot picture any kind of short that might cause them to argue. Testing for resistance/continuity between terminals on the balance board shows resistance for a a split second before it opens completely. This seems to be the source of the spark. The bms has short circuit protection. It does not seem to hurt the bms. I disable balancing using software for the bms so the blanace board can work without interruption. What do you all think? Is there any reason the bms might be damaged?

Update: ICGOGOGO responded saying yes it is safe to run in combo with a JBD smart BMS.