Cheap Active Cell Balancer Test (Fail)
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- Опубликовано: 16 окт 2024
- Active cell balancers are supposed to move electricity from high cells to low cells, keeping the whole pack in balance. Active cell balancers can sometimes be costly, so I was excited to test this cheap one when it came on the market. Unfortunately, I was disappointed in the results.
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hi, the cheap active balancer works fine but it is very very slow compared to the other, you need not one night but several months to balance those big batteries. The problem with this cheap balancer is: it didn't balance the lowest cell against the highest cell like other balancers. It balances each cell against the adjacent ones, the one on the left or on the right. So in worst case, if your pack is unbalanced with cell no. 1 highest and cell no. 16 lowest, this balancer needs 16 steps to balance the complete pack.
And that is a terrible design for more than 2-3s packs.
As usual, the devil is in the details.
I love how you accentuated "inexpensive"! Good info!
Just watched a video on tolerances...it appears that is the problem with the "cheap" balancer. Nice and informative vid again David. Thanks
These active balancers have a bi-directional buck switchers between two cells. They make a voltage comparision and buck from higher voltage cell of two cell pair to lower voltage cell of pair. The buck switcher IC's are leap frog overlapped so charge can be shuffled up or down the total stack of cells.
Problem is the buck switcher IC's operate unsynchronized which caused the possibility of adjacent switchers to be pushing current into one of two cells while its voltage sense measurement is being made. This causes incorrect decisions on which cell in pair has higher voltage and results in charge transfer in wrong direction. Small gauge wiring voltage drop from 1 amp current balancer to cells aggrevates the issue. Pushing 1 amp through 6 feet of #22 wire has 100 mV voltage drop which will effect reading at balancer IC compared to actual battery terminals.
Any balancer needs to simultaneously snapshot voltage readings on all cells at the same instant in time to account for variable load current on cells due to inverter load/charging that may change cell voltage reading at differing points in time.
The DFN packaged version could be made to work by adding a syncronizing reset function every two seconds with something like a 555 timer IC, level shifted to all Enable pins on the balancer IC's on the board. Unfortuately the PCB boards with DFN package parts do not connect the EN pin and it is very difficult to make the connection to EN pin on the very small package. SOT23 packaged version part does not bring out the Enable control pin.
It is unfortunate as the principle is sound to make a low cost active balancer. If the IC manufacturer used the enable pin to self synchronize all the chips it would work.
You know, I've spent better part of the afternoon looking for any documentation on how exactly these small active balancers work. There are hundreds of tests and surface level descriptions, but no sound documentation anywhere!
So far, this youtube comment is the best description I've found.
David:
From your description, you had both balancers connected in parallel to the battery bank. Whether the green balancer was balancing or not, it was still monitoring (thru the app) and therefore powered. I believe the green circuitry was loading the battery outputs and possibly affecting the black balancers' ability to balance.... Just a thought.
I thought as much, this was my first thought. Could the other balancer be disrupting the function of the cheaper balancer was my first question when I watched this.
As far as I know, his cells are of large capacity and this shouldn't make any measurable difference. The green balancer should definitely be drawing significantly less power than what the smaller balancer is able to balance.
This is most likely the issue of his cells and loads being greater than what the small balancer can manage.
I've bought that black active balance board also, with a very similar outcome on unbalanced cells.
For your project use the deligreen 1s balance active one by one
I just ordered a mid-range unit. It's 5a balancer with large red caps. Not a lot of reviews but all the tests ive seen show that it can balance wildly out of range voltages and works for powerwall sized packs. May be a good video idea, they're $40 on AliExpress
same for me, just tested smaller balancer and it failed...
waiting for bigger balancer to arrive, hopefully it will do it's job.
David, I've enjoyed following your project. Regarding this episode on balancing your group of batteries I don't recall seeing anything about you Bottom Balancing the packs. I'm just a novice and haven't built anything yet but it seems that this is an important step especially for LiFePo4 batteries so I thought I'd mention it. Thanks and I look forward to seeing a few more episodes before you can enjoy just relaxing and enjoying the benefits of you DIY power wall!
Hi Mark, These batteries have been sitting over a year before I got them. So I have to cycle them a few times to bring them back to life. After they are conditioned I'll be top balancing the packs. Thanks for watching.
yes, i had one of those active battery balancers, it was really expensive, it moved power from cells to cells, but made cell balance worse as well.
i think one of the problems is when they balance on the lower voltage atstead on the upper voltage only
The cheap balancer works fine for smaller batteries, but because it can only balance between neighbouring cells there is a limit to how effective it is on large setups. There is a 99-30mV difference between cells , so you could have up to (if my math is right) 14 x 99mV and 14 x 30mV difference between cell 1 and cell 16 which is 1.26V to 0.42V difference. So your 0.2V is actually well within spec for this device.
On a smaller pack, say 3S or 4S the difference would be very low. So I think these boards are best suited to smaller packs if you want precise balancing.
Oh boy! I've ordered these for a 60S pack!! To kid myself, I presume that when drawing current different cells will be high and low from when charging the battery , so the error averages out to some extent by cycling? Further my solar charger multiplexes so only charges 12S at a time, so the maximum error is across 12 cells. Other youtubers on this balancer seem not to be near the worst case scenario when testing this and even get less than 30mV between adjacent cells, but that can be measuring errors using cheap multimeters as most of us do.
I just hooked 3 of my BYD battery pairs up to these "cheap" balancers and they worked far better than nothing. I was having trouble with a cell or 2 reaching 3.65 during charge, leaving all the rest at 3.4 or even 3.3! This board straightened all that out on a slow overnight charge. I put 20 amps into 6 batteries total and they are now within .026, .057, .010 which is a lot better than .3! I think your green one would do a better faster job though. But I'm going to see how this goes.
BTW, I only have 3 of these because that's all they sent. I ordered and paid for 5, one for each pair of BYD's . So I'll just move them around for now. I'll send them another email after President's Day weekend (they are in Kentucky).
Just wondering if you ever checked the reported voltages of the green balancer against a good volt meter? I saw someone tested another balancer which didn't read voltages properly and would cause cell imbalance like the black one.
Yes, I have. It's close enough. It was awhile ago, but I think within 6 mili-volts or something to my multi-meter.
@@DavidPozEnergy Thanks.
Merry Christmas
I have a slew of the 4S models of those. I think the issue is they're not calibrated (they're also not fault tolerant I burned a couple up...). I can swap the 4S ones out on the same battery and get different lights lighting up. Really have to use 1% or better parts when making something like this which these cheap ebay balancers are not.
My BMS allows me to top balance as long as the current isn't too high so I have to charge my 12V lifepo4 pack at a relatively low current (1A or so) which is fine for me since I rarely deep discharge it
tl;dr they're junk
I guess you get what you pay for at least sometimes I bought 2 of the green ones but only one worked.
Very interesting !
Bummer. I own one also but my cells are too close in balance, 10-20mv to actually test it out. Supposedly the balancer will only start balancing once you hit 100mv (.1 v) difference but so far my pack / cells have not wavered higher than 20mv.. Interested in your upcoming BMS test.
Yeah I noticed that too. But 0.1 volts out of whack is too much for LiFePO4. I want them to be closer then that. Another good reason not to get it.
@@DavidPozEnergy totally agree
do you have any updated info on active balance boards ? is there a link to the green board ? I'm shopping for one for a 48V lipo pack. Thanks.
Congrats on the battery bank.
I have an 8S version of the black board with LEDs. So far it's worked really well but I've not used it much.
i did nod found the other videos about the green bms. what kind of bms is that?
Hi David, in one of the comments you said you were going to use a Chargery BMS. Did you ever do that? And if you did, did you make a vid of it? Greetings, Rik
Yes, the chargery brand BMS is installed. However, I never could get it to work correctly, so I never made a video on it. I don't recommend it.
Thanks !! Very useful video .. ta
What do your prefer BMS or Active balancer? Seems to me the active balancer along with a good charge controller is gives good control if if the balancer is good.
I prefer a BMS first. But an active balancer is a nice thing to add after the BMS
both. the BMS protects the cells from over and under voltage, over current and short circuit while the active balancer keeps the cells balanced without losing much charge on the pack as a whole.
I believe that the cheap ones can only move energy between batteries that are next to one another in their pinout - that is, cell 1 can only share energy with 2. Cell 2 can only share with 1 and 3. Because of this, they have to "shunt" power down the line of batteries to get power from cell 1 to, say, cell 6. They are forced to put it into cell 2, then into 3, then into 4, then into 5, and finally into cell 6. So they're ideal for small packs, really - 3S would be the absolute ideal for them, 13S is asking a hell of a lot of them.
ruclips.net/video/40rAkqBz8Vk/видео.html
Your bluetooth balancer shunts the power into it's capacitor bank, and then directly into whatever cells is lowest. In other words, it can go from cell 1 and dump energy directly into cell 6 (or 12, or wherever it needs to go). I think you'll find that the cheap, capacitorless balancer would work ok on a small pack that has fairly well matched cell groupings, just to keep things balanced as you charge. Essentially I think it's designed to work on ebike batteries that never see more than a few percent imbalance, not anything big and beefy. And nothing super imbalanced.
I have a 7S el-cheapo balancer unit on order for an ebike battery test rig. And a 7S BMS. Gonna deliberately unbalance the test rig and see what happens, but for rigs the scale of yours the bluetooth unit is probably a far, far better idea.
Can you know what this is like?
It's a balance board mounted on the lifepo4 4s, but the balance is too precise. Just perfect. So I'm looking for the same thing as this, but I don't know where it is.
prntscr.com/whmmlo
Thank you
Hello David,
what do you think, can I use an active cell balancer instead a BMS. Why am I asking? I have the idea to use 4 Lifeo4 (3,2V 125AH) prismatic cells to build a 12V pack and charge them with an AGM Load Curve to 14,4V. So I think I don´t need overcharge protection. (One reason not to by an BMS)
Another question I am having is why does Lead Accid Batteries do not use a BMS ( They have 6 cells with 2V and has been used since lifetime without balancing and BMS. A bad series connectes cell has the same electical physics to me as Lifepo4.
Are these 200A 4S BMS to power a 2000W AC step-up converter behind a Lifepo4 pack mandatory or just waste of money? They can break and you don´t even know it or shut down the whole system. This can happens as well with common port or seperate port.
Can an active call balancing and a lower voltage cutoff and a nice 200 Littlefuse system an option?
What dou you think and do you have any ideas what active balancer could work.
Buy the way my system is design for an RV with 230V 50Hz and a 300W solar supply.
Thank you nice channel, like to see more of your projects
Bob
I recommend always using a BMS with lithium batteries. Sometimes things can break, but it's rare if you size components well and set up automatic controls.
David what would suggest I use for a BMS for my Leaf batteries. I am going to use 48v. So 7 leaf batteries in Series. Also can you supply the link for your green active balancer in this video? Thanks loads. Mike
Which BMS to use. This depends on how many amps you need to pull. You could buy a cheap little BMS for $40 if you only 20 or 30 amps. Or you could spend a grand on a Batrium: www.batrium.com/collections/decentralised-supervisor/products/watchmon4-exp-leafmon
Balancer: www.aliexpress.com/item/4000252216391.html?&srcSns=sns_More&tid=white_backgroup_101&mb=No5ewoeO0rRW8pX&tt=ae.CopyActivity&fbclid=IwAR0lW8iwrTT9KTPlG6tkZX-lsCP73xnliK7AxT12iRkzHYNT11MAuvyd1q8&rdtUrl=https%3A%2F%2Fwww.aliexpress.com%2Fitem%2F4000252216391.html%3F%26srcSns%3Dsns_More%26tid%3Dwhite_backgroup_101%26mb%3DNo5ewoeO0rRW8pX&aff_platform=default&cpt=1576778475931&sk=FFhITpnE&aff_trace_key=5063c2a474ac4884a831f8c8274dcdd1-1576778475931-08776-FFhITpnE&businessType=ProductDetail&platform=AE&terminal_id=aea5cb8e6c504178ace6f2aadc4d8eea
Hi David, I bought two of these batteries and am now planning the rack to hold them. I was wondering if the orientation of the battery would matter. To save space I would like to mount them on their sides rather than the bottom (or top). Do you think placing them on their side would be a problem. Thanks
I'm sure it's possible to rig up something that keeps them on the wall vertical. It will just take a bit of engineering.
Thanks for the response. I was more concerned mounting them on their sides might damage them in some way. Any thoughts?
Lithium batteries can be mounted in any orientation, so that's not the problem. The problem is getting them fastened to the wall without crushing anything. The plastic case around them is pretty strong, but not made to take all the weight of the cells. And if the plastic deforms over time (from sitting on a shelf) then the weight would be on the cell tabs which would cause damage.
I ordered some of those batteries a month ago but nothing has arrived. Maybe you know someone over there.
Nice work bro.
What battery charger you going to use and what BMS board you going to use for this battery setup?
I'm using my inverter as a charger, and I'm going to try a Chargery BMS. Thanks for watching.
@@DavidPozEnergy I'm planning to use Midnite Solar Classic 250 MPPT Charge Controller with Smart Lifepo4 li-ion Lipo LTO Battery Protection Board BMS 48V 72V Bluetooth 20S on this 4.5KWH LiFePO4 Battery Modules setup with 48vdc
DavidPoz Doesn’t the chargery bms balance the cells? If so, do you need this active balancer?
Yes, the Chargery BMS has a balance function. It uses resistors to burn off the electricity from high cells. This is wasteful. I like the idea of active balancers that maintain the electricity, but move it from high cells to low cells.
@@DavidPozEnergy So are you going to use BMS to charge and protect battery and use balancer for balance function ?
The active balancer will not start working unless there is a .1 volt difference between cells. Probably not as accurate as your resistive balancer
have used the 7s version of the little black board with led's version on a 40ah pack for a year everything is balanced still. what store did you get that from?
Which store did you get it from?
Question not directly about video. When you had cover of the new batterys could you tell how easy it would be to make a single 24 volt pack by rewiring the cells ? I ask because I am going to buy some and would also like to use one on a 48 volt golf cart. If I buy an odd number and can't convert it fairly easily I would be stuck with one battery I couldn't use. I know I could use two of them in cart but would rather not and with the weight savings one should provide as ,much or more range as the Pb acid ones .
sorry typo off and mistake single 48 volt pack
There are 8 cells inside each module. There is no way to break them down further. So if you want to make 48v, you will need an even number of modules.
The little balancer that I have works on adjacent cells if the difference is 0.1 volt or more, and balances down close on those adjacent cells. Not really ideal for real balance but it might do something to bring up a low cell, but only about 1 amp current flow.
I've bought a few of these for used battery packs, and their ok, but sort of work
These balancers are not suitable for LiFePo batteries (even sellers says they are suitable). Those boards use ETA3000 IC's. Those ic's are designed for Li Ion batteries. Eta3000 needs minimum 0.1V difference between cells to kick in and since lifepo batteries have straighter voltage curve so it might not work
Looking for the wire harness with connector for the BMS 14pin have any ideas where I might either buy the connector as a whole or make my own with pins connector and wire?
www.mouser.com/Connectors/Headers-Wire-Housings/_/N-ay0lo
Molex has any wire connectors
what fuse and rating are you using on your battery positive terminals?
The fuse you see in the video on the positive post is 150 amp, Class-T. I'm working on a video talking about them.
That seems to be a very good Battery MURDER system,LOL
IT WILL ONLY BALNCE CELLS OVER 0.1V DIFFERENCE. IT WILL ONLY BALANCE THEM IF THEY ARE NEXT TO EACH OTHER. THIS TWO LAST THINGS MAKE IT ONLY/ MOSTLY APPROPRIATE FOR SMALL SERIES CONEECTIONS. It jut works fine but not for your purpose. They were already within 0.1V when you took the first screenshot so the device pretty much did nothing
I have the same problem with those balancers. I set my 12s battery up with one cell off by 0.3V. Hooked 6 different balancers to same battery (one at a time). All 6 of them attempted to balance different cells instead of the cells that was out of balance!!!
Julian Illet did a video on how each active balancer is one way, 3 to 4 but not 4 to 3, which cause havoc pulling down adjacent cells. But to be fair they’re designed to be used during charging so theoretically their impact is smaller.
I do believe you misunderstood Julian Illet. please watch his video on the subject ruclips.net/video/Fb52fVaMeY8/видео.html
heya that can happen go you doing these test's so you now what is good and what not
i suppose your cells are too unsimilar or you have highly leaking cells inside your stack.
May be because the black one is for capacities less than 30Ah
Idol👌🏻
As far as I understand these active cell balancers they measure the internal impedence of the cell as part of its calculations. If you had another cell balancer connected at the same time this would cause false impedence readings which could explain the cheap one not working correctly. On the other hand you could have been sent a faulty board as other channels have. When they tried a second board it worked perfectly. The quality control is non existent on these cheap boards so there are a few dead ones being sent out.
And this is why you don't immediately yell "get a BMS" to every situation. A low quality BMS is much worse than no BMS at all.
I have LiFePo4 cells, bottom balance and no BMS.
yeaaaahhh, wait until your pack has been through 1000 charge/discharge cycles, and THEN see if it's still bottom balanced... I guess you'd never know until it's too late, because you don't have a BMS :-(
Did you really expected for this SMALL balancer to balance such huge batteries? 😂
It's not about small or large its these things just are bad I have a 7s one I used on a small battery and they just aren't accurate or work properly. Frustrating also how expense these vendors ripping people off
plojm123 well... it’s just like charging your Tesla from aa battery 😁
@@andreym325
he is not charging the battery from the bms. the bms is trying to balance the cells. so if the bms has low balancing current it should not make the balancing worse at the least.
@@ursodermatt8809 I know lol, I'm good with batteries
They dont ship to Canada
batt go worked great for my lifepo4 packs it took 2 days and they are steadily at perfect balance even after discharged and charged they end up within 2 millivolts of each other..
but the battgo waste charge, as the active balancer keeps most of the wasted charge
Thanks for testing I was considering buy some. Now I won't.
I use smart bms which I can change to either active balance or charge balance. I generally leave it on charge balance unless I see something fishy like a battery that is more than 10 percent off the others and if active won't fix it then it's time for tearing down the pack for repair.
I see you plugged it in wrong, you need to connect the B- side first.
David,
I was really disappointed with your results, as I was hoping to use this active cell balancer too. I watched quite a few other videos on this balancer.
Check out this one.
ruclips.net/video/40rAkqBz8Vk/видео.html
It shows a 4s setup moving current around, with a max value of 1.44A.
Was your issue with the final balance result, ie not all cells had the same voltage, or that the charge current was not good ?
Brian
I've also seen that video and others. Perhaps this balancer is fine for smaller setups, but not a 16s battery. My issue was that it made my cells more out of balance. (worse)
@@DavidPozEnergy
Looks like the spec on this active balancer is not so good. From the web page on EBAY they claim that:
"Working principle, the inductor converts the transfer charge carrier. When the battery error voltage is above 0.1V (100mV), the balance work is started until the error is stopped at 30mv. The built-in improved ultra-low internal resistance MOS, the balance current is 0-1.2A, and the battery voltage difference is smaller. The smaller the current, the static power consumption does not exceed 20uA! With balance instructions!."
So it appears the best you can do with this active balancer is 30mV, and to even start moving current around there has to be a 100mV difference. Perhaps not what we were all hoping but it does appear to be working to spec.
Junk balancer. I got the same and it failed in 15 min.
Like #430. Thanks for sharing!
Thanks. Looks like you are going through the videos.
@@DavidPozEnergy Caught up. I think I've watched/liked them all. Keep sharing - thank you!
Thanks for watching them.
Hi David, I'm have QNBBM equalizer.
Those look like the best out there
If you bothered to read and understand that particular balancer works only to balance cells that are 300mV or more in voltage differential. It will do this anywhere in the charge cycle, unlike most which attempt to top balance only in that small window when battery is close to fully charged. Another unfair China bashing video.
Many others have had success with them
I think you may not have understood how the active balancer works.
Here's a vid that should help you to better see what the device does. What you saw with your monitor would likely be different once you disconnected the active balancer or you unfortunately just got a bad active balancer.
ruclips.net/video/40rAkqBz8Vk/видео.html
Only bla bla bla