Cheap Chinese Active Balancers

I have noticed that AliExpress have recently started offering "Active Balancers".

Knowing that these JUST balance and are not a complete BMS, has anyone had any experience with these?

https://www.aliexpress.com/item/33002903687.html

https://de.aliexpress.com/item/4000181271387.html

There are apparently 2 types being offered. The second type appears to use capacitors to transfer charge from cell to cell, but not sure about the first type.

Dave

The first one has been reviewed by Julian Ilett:


There's someone else who's done it too, but I can't remember who did.

There's a few threads on active balancers. Haven't really wanted to tinker with those cheap under $20 units. But have looked at some more capable units.

QNBBM, expensive when scaled up since they're 20 each. So for a 14S it would be $280.
https://www.aliexpress.com/item/32997199343.html

No name 1A balancer. Not configurable, but balances to 40mV. I use these currently on my 7S300P build. Since they have a serial output that I use to log the data in my build. Under $100 for a 14S setup. If you look at my build I did some small test on it. I'm actually more interested in the one below that I'm waiting to arrive any day.
https://www.aliexpress.com/item/4000061285529.html

Another 1A active balancer. This is highly configurable, and bluetooth output. Just bought one of these to test. Under $100 for a 14S setup.
https://www.aliexpress.com/item/32985346022.html

This looks built to last:

https://www.aliexpress.com/item/32906812693.html?spm=a2g0o.detail.1000023.3.29331335rWmKz9

Overmind said:

This looks built to last:

https://www.aliexpress.com/item/32906812693.html?spm=a2g0o.detail.1000023.3.29331335rWmKz9

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Why? Just because it has big resistors?

In all honesty, there is no need for an active balancer in a powerwall. If your battery bank is constantly balancing, there are either cells near failure or the batteries are terribly mismatched in terms of capacity. It's best to address the underlying issue rather than masking it with an "active balancer" and hiding other potential problems/warning signs along the way.

Yes. I did have some problem with resistors including on various chargers like Xtar. Soviet-era resistors always permanently fixed the problem.

mike said:

In all honesty, there is no need for an active balancer in a powerwall. If your battery bank is constantly balancing, there are either cells near failure or the batteries are terribly mismatched in terms of capacity. It's best to address the underlying issue rather than masking it with an "active balancer" and hiding other potential problems/warning signs along the way.

Click to expand...

I disagree on that an active balancer is useless. I think that term should apply to all balancers. An active balancer just works differently, but otherwise works like any other balancer would. Being active doesn't necessarily mean that it's always balancing. It just means it's not passively dissipating the energy as heat like a batrium would. Instead it's transferring some of the energy back into the system. The active balancer can be set to only balance at certain deviations, therefore should sit idle most of the time, just like a passive balancer would. Its only advantage is that it doesn't waste the energy during the balancing. My wall stays under 30mV difference at all times. It can do that for months at a time. My active balancer only kicks in at 40mV and it does that only occasionally, so bringing in some of the slightly out of balanced packs. That is a normal occurance.

So the correct thing to say is that is no need for a balancer in a powerwall.

So if you dont balance you dont move any energy and therefore a passive ballancer would have been cheaper

What Mike and me and many other is trying to say is that the cost getting active balancer does not pay off on a proper battery bank. With that said moste of the "cheap" active balancers only HIDE the balancing done meanwhile a decent passive balancer even reports back on how much off a cell is.

I calculated it and on my battery bank it would take 15+ years before i even save anything buying active balancers instead of the passive i had today.

Also note that you generally balance when you have excess energy that in most cases also gets wasted.

Add upp the fact that an active balancer also wastes energy so for the purpose they are built they are ment to balance during bottom and top meaning they always move energy back and forth...

Active balancer have their purpose for sure but in most powerwals they only hide whats going on and people need to understand why you balance and when before masking it.

I would say "It should not be needed"

I don't see how an active balancer is more expensive than a passive balancer. Last time I check a decent active balancer that is configurable is under $100 for a 14S setup. So cost is not an issue here. If you're trying to calculate the ROI of a active saving you money, then yes I agree it's never going to pay back. An active would be more efficient in how it's balancing, so reduction in heat. Again, you're under the general assumption that an active balancer is balancing 100% of the time, wasting energy transferring between cells all the time. That's not the case. You set it to only transfer when there is enough deviation between the cells. Over time you can tell which cell is always going out of balance just as much as a passive system would since it will always be the highest in deviation.

these are the ones that I have used. the top one, I boughta 4s version for 12 dollars, and connected to an out of balance battery, after 5 hours nothing happened, it was still out of balance. I bought 2 of them and both perform the same, they are useless to balance a pack.

The middle one, I bought the 4s version(20 dolllars)and Also after 5 hours the battery was still out of balance but it did balance a small bit. But it would be insignificant.It does work but very slowly, it would take days to balance an out of balance pack. But it will keep a pack that is mostly balance, in balance.

The bottom one I also bought a 4s version (95 dollars) that one actually works and I use 24/7 on a 4s 220ah lifepo4 that has balancing problems. This one keeps up if you like to fast charge your battery.

I like my batteries to be in perfect balance, thats why I use the active balancers. I also like to fast charge my packs, active balancers lets the battery stay balance close to the top end, without the balancers I would never get a full charge on my 220ah lifepo4 pack, the bms would activate too early.

jonyjoe505 said:

The middle one, I bought the 4s version(20 dolllars)and Also after 5 hours the battery was still out of balance but it did balance a small bit. But it would be insignificant.It does work but very slowly, it would take days to balance an out of balance pack. But it will keep a pack that is mostly balance, in balance.

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That's curious considering it's supposed to transfer charge at the rate of several amps - so I guess the rating is bad. Do you have any data you'd like to share with that unit?

I just bought the same one *facepalm* so I'll be testing it as well. I've been working on a DIY BMS, and the most annoying part for me has been the balancing. What I liked about that unit is that it has an on/off switch (a trace on the PCB you can cut and hookup to a switch) to turn balancing on and off.
I'd like to also measure the current and see what it is actually balancing at.

Based on your feedback it seems like it's a dud and I might be better off with what I was doing - a resistive balance board that is separate. Either way I'll test it and share my results.


Other than that - a BMS system would just need to do low and high voltage cutoffs which is much easier to implement. There are a bunch of cheap $20 current meters on amazon that... well they aren't perfect but they are close enough for users like myself who are using sub 5kwh systems

there was a new versionthat came out that has red capacitors instead of the blue ones,. its suppose to be an improvement. The ones I have just don't balance fast enough. When I tested it, I used a severely out of balance pack, and its performance was not good. During the test I also used a 3in1 lipo tester (which has resistive balancers) the 3in1 tester(cost 10 dollars) easily outperformed the active balancer.

The chargery bms8 that I have on my 4s 220ah lifepo4, has 1.2 amp resistive balancing, you can adjust at what voltage you want them to come on, you can also turn them off.Very good bms all around.


3in1 tester works better then the cheaper active balancers

I bought the red resistor one myself. I checked youtube and looks like one person made a video which... I can't really decipher but I think it shows him getting almost 5amps of balancing current in his testing.

Looks like his setup is 5 cheapo multimeters soldered on to measure current draw, and that exact 3in1 tester you have to measure voltage.

He's even tested this 1a version and it seems to be working...

What I would use is the 5amp version - which would be automatically controlled via my bms. This way I can also keep track of how long equalizing was kept on for

Thanks for starting this topic. i have a similar story.I have 12x or so of those BAE bus packs and 480x new 32650 lifepo4 cells, totaling 1584 cells and 15kwh. each half of the battery has itsown high qualitytop balancing BMS, but and a strange thing happens recently. Overnight it would turn off and error out my magnum inverter and transfer switch, leaving me in the dark. when i commissioned the system in august 2019when it was sunny, it would top balance every day sitting at 54.4VDC for hours and i never had issues. now that we are into the late fall in the northern hemisphere, and i have double the pack capacity size over time from 7.5 to 15wkh, it almost never gets to 3.60V/cell which is the threshold for balancing in a typical LI-FE BMS. so in a matter of a 3 or so weeks one of the cell layers out of 15swas drifting down to 2.5V/cell when the others are at 3.05v/cell causing the BMS to activate the protection circuit and disconnect the power before my transfer switch got to its own 46.5 volt trigger level to go back to grid.

I think the solution is to have both an active and passive balancers on at the same time. the top balancer provides over and under volt protection for the pack and the cell levels(the stick.) And the active balancers provides more capacity and balance with shallow cycles between middle and low charge levels(the carrot.) i'll be in $140 for both active and passive ballance at the 100amp/150amp/hour scale. my red-cap'ed 17-16-15-14sactive balancers will arrive 1/2020 and cannot wait to install them with the shortest possible butequal length, 16awggauge wire, until then i'm manually bottom balancing the packs with a smartcharger once a week. i have a youtube channel search for solar porch nissan leaf.

No
Active chinese cheap balancers Will hide your issue and just delay it slightly. The problem above is that you didnt check it in time and fix the issue. For instance swapping out the self dischargibg cells.

Another is to set balancing to start eatlier. You state you have a high quality bms then you can set that.

Dont hide the issue you have. Fix it instead. A proper passive bms would handle it even without not getting a full Charge.

Getting active balancer is just an excuse not wabting to remove cells that are faulty

daromer said:

No
Active chinese cheap balancers Will hide your issue and just delay it slightly. The problem above is that you didnt check it in time and fix the issue. For instance swapping out the self dischargibg cells.

Another is to set balancing to start eatlier. You state you have a high quality bms then you can set that.

Dont hide the issue you have. Fix it instead. A proper passive bms would handle it even without not getting a full Charge.

Getting active balancer is just an excuse not wabting to remove cells that are faulty

Click to expand...

There aretwo Li-Fe packs each 7.5kwh, one with brand new cells and one with used BAE bus packs. both had the issue where the BMS would go into protection mode after a few weeks of not top balancing. my BMS is not programmable.to get the low cell layer back to the same volts as the other cell layer (2.5v up to 3.15v, a bottom balance) itput1.5ah into the new cell pack and 750mah into the used cell packwith the smart charger, consider each isa160ah cell layer, that is lessthan 1%. is that really a problem? based on that i figure a 5 amp active balancer is many thousands of time overkill to meet the need of making up1.5ah over a fewweeks.

IF its less than that in drift its not a problem and i dont see why you would even consider getting expensive active system hiding it.

I have alot more drift over Winter than that and i dont get into issues
IF that small amount is tripping under voltage you drain the pack to much from start.

Chasing that last 1.5ah isnt worth it

Hi ,Dave ,
The active bms wasn't a cheap balancing bms , so that 2 options you had posted
Wasn't active ,that's balancing by resistance
Wendy
<Email removed>

So this 1A JK-B1A24S active balancer I have now comes with a new version that has CANbus. I was going to try and figure out how to communicate through the bluetooth interface but wish I'd waited and got this instead.

https://www.aliexpress.com/item/4000252216391.html

The seller has provided some documentation on it, and I had to do some google translation from chinese to english. Thought this might be useful to someone.

I've had the red cap active balancers 15s installed for 17 days and the cell layers are within .01v, so they definitely work. Also I do think they unlocked more capacity, 1/6/2020 was really sunny in Ohio and I charged up record 15.3KWH.This chart shows a day from fall 19 without the active balancers and then then both 1200xBAE + 450xVaricore batteries with active balancers, so two things changed, but Im happy with it.