I got the 7s version of this and have tested it for 2 months. Works great so far. However, we need a version 2 of this because it only monitors differences of adjacent series. We need one that takes an average of all 7s and tries to bring every series to the average voltage otherwise what happens is that at 0.03v accuracy multiply by 7 = 0.21v. In theory, the 1s (first series) can be at 4.10v and the 7s can be at 3.89 (-.021v) and this balancer will not care. This will become worst with a 14s pack and so forth.
Would have thought this was an ideal opportunity to get out 4 ammeters, looks forward to the reverse engineering, and hopefully a rebuild with capabilities of 10 amps :)
I have one AB for 16S and it sits. I never thought it can go that low on voltage. Since I am building 6S SC pack now I can use this balancer finally. Great video. Thanks.
The circuit is similar to a synchronous buck switcher. A synchronous buck converter has an active MOSFET for rectifier as well as normal coil charge MOSFET switch. Because it has two MOSFET's to series coil it can buck in either of two cells direction. The I.C. measures which one of the two cells is higher and buck transfers from higher to lower voltage cells. Multiple IC's overlap every two cells so it can bucket-brigade charge transfer up and down a series stack of cells. It actually worked better for you then I expected for the 2.5v supercaps although you did not measure transfer current. Problem, which you eluded to, is as the cell voltage is lowered, the gate drive voltage to the MOSFET switches is reduced. This causes their ON resistance to go up reducing the buck switcher transfer current and creates higher switching losses.
Definitely want to see the lithium ion in action...to see how well it can handle an almost completely flat pack to full charge how close it maintains the cells till it reaches full charge Might be a good way to safely charge a battery pack with multiple cells if it can actually maintain good balance from dead to full charge in all the cells, especially if there is a weak cell in the pack
@@appleejack A lot of S C manufacturers will use the same case to keep a standard form factor. The dimples take up interior space when using a lower value capacitor BUT keep the same outer diameter. Think of the dimples as filler material.
Mr. Ilett, I bought a 14S version with the intention of reverse engineering it for a much higher current transfer and can confirm that it does indeed squirt 1.2A when connected to Li-Ion batteries. I've got a rough drawing of my work to date, if you want it.
I wouldn't just yet. I've attached it to my 14S 80P powerwall and it takes forever to shift a 200mv difference. When Julian comes up with a 20A version, he'll make us powerwall chappies very happy.
@@peterpurpose ah thank you... I am assembling 80p packs so I appreciate the insight. My first 14 packs contain identical 2000mah cells that i've already capacity tested, so they should be pretty closely balanced in capacity... but when I expand I will be dipping into different cells, so a larger bms will be needed then. Have you used a resistive bms? I would think even this stock would beat one of those aince they tend to do a wimpy 20ma draw or similar.
That an interesting product for some niche cases where you get large unbalance and are in desperate need to save every bit of power you can. Often balancing difference with good cells is not that large and passive systems do not waste that much energy.
Indeed. I made a 4S lifepo4 battery pack from new cells (all same batch) that I was prepared to balance manually - about 50 charge/discharge cycles later I've never had to balance them (never been more than 0.01v different at top or bottom of charge). Interesting.
I think this module is interesting in the case of refurbished cells in a pack. Given that this kind of cells have very different characteristics, they will get out of balance pretty soon
That board would be fun to play with. You could use a voltage divider and have it drive a relay or a different boost board externally with higher voltage cells or even 12 volt batteries in series.
Put a Volt Meter on each capacitor and you'll see it's not boosting any voltages. It is bucking all voltages. So it takes the higher voltage of 2 cells/caps, and bucks it down to the lower cell/cap. With the inductors, it must do it using pwm, which makes sense because it needs to be decoupled when transferring the energy, otherwise a short will occur. So, when you pull the energy from the center cap, the device will then buck the voltage from cap 1 down to cap 2, and buck cap 3 down to cap 2, until cap 2 reaches the voltage of caps 1 and 2. (This is how I understand it works. Altho, I could be wrong on this setup and would love to see how it really works) A neat trick I'd like to see tho, is doing something really wildly extreme on the votlages. Make cap 1 at 2.3V, cap 2 at 2.0V, and cap 3 at 1.9V, and see what the unit does. Will it start transferring from cap 1 to cap 2, as well as transfer from cap 2 to cap 3?? Will it go sequential bouncing back and forth? will it fry itself????
Wrong way to look at it. The device uses a Buck/Boost topology (check the datasheet and the various papers on on these balancers), and whilst the output voltage is clamped by the cell being charged, to get a decent amount of balancing current into that cell you need something capable of generating voltages higher than the cell.
I'm currently waiting for a 3S version to arrive, for balancing the packs in my current Solar Energy Accumulator (often known as solar generator)project. These modules look very clever, and more efficient than resistive balancing the cells.
Finally I have always felt that over voltage balancing by burning off excess voltage through resistors was just wasting your already stored energy. At least this uses that energy to charge your lower cells.
Heres more interesting, multiplying the balance current by connecting parallel boards.this test uses five of this cheap 3s boards. ruclips.net/video/Kg8SeHJVsWY/видео.html
Good data there Julian. I use active balancers from Deligreen, constant functions to bring or maintain a lithium-ion pack to on or below 10ma up to 8amps per cell 4.2v max.
Honestly, I don't think I have ever seen a balancer circuit actually work the way we all want it to work. It's all about ohms law, very small voltages / small resistors = very small currents. I think you would not of seen any difference between a pack with the balancer and a pack without the balancer. You would have to have a bad cap or cell in the pack to see that balancer do anything noticable. Interesting video, I like your common sense approach and the fact that you don't rehearse before doing the video.
This would be more clear if you were not also charging the stack at the same time this balancing board is supposed to be trying to help. How about getting 3 volt meters and repeating the experiment, and leave the charger off? I can't tell if it's this magical board doing the balancing, or your existing protection devices with this board just reporting a voltage difference?
The purpose is not to draw 12 volts from a 24 volt battery as many people erroneously believe and constantly erroneously post. The purpose is to lengthen the lifespan of any battery and increase it’s effective amp hours because balancing allows you to get more out of the fuller cells because your BMS doesn’t kick on from early polarity reversal in a less full cell. This thing is amazing for a 12 volt battery, or anything that uses more than one cell in series. (Series batteries are dangerous if a cell is empty when the other cells are highly charged masking the empty cell)
Will Prowse reviewed them a few weeks ago - he was initially impressed, but then suspected they weren't charging low cells and instead bleeding. Need Julian to do a proper test!
Very nice. Do make the lithium version please. Would be cool to measure the current going through the individual leads. I've been looking for a cheap active balancer for ages. The only one downside is these will hide a dying pack as you won't notice it sagging.
I tested this module and the current depends on voltage difference. Grather the difference bigger the current it transferrrs from one to other cell. Curent is linear to voltage difference.
@@JulianIlett yes, at a difference of around 1V it will be 1A maby less . And as the difference drops drops the amperage too. The device gets pretty hot at 1.2A so be careful.
Most types of batteries have difficulties when configured in parallel (same voltage, increased amperage). It is common to have a cell that isn't staying at full voltage (what it's voltage would be if not in parallel). This device enables automatic switching in a parallel circuit to ensure your batteries stay balanced.
I got 4 of these balancers on eBay to use on my 14s Lithium ion battery pack. First one burnt with smoke when I plugged in. Second one kind of worked. However in a 14s pack, with minimal 0.1V difference for the balancer to kick in, the worst case scenario there can be 1.4V difference in voltage between cell with minimum and maximum voltages. After all I went ahead with a capacitor based balancer with better sensitivity.
In your worst case scenario 1,4v. (In theory) That means that the best cell triggers the BMS at 4,2v so the charger stop. And the worst cell is at 2,8v. That will never happen in real life. Liion are empty at 3v so the charger never charge and your battery pack have no energy.
So, with 17 cells, and one in the end very slowly losing charge you'd eventually get somewhere between 0.48 and 1.6V difference between highest and lowest cell, as balancing stops at 30mV, but doesn't start, and therefore restart until 100mV difference?
Thank you very much I learned a lot and you helped me make an informed decision when ordering BMS for my lithium 18650 project. REASON!. I wanted to make a 4S Li-Ion standby charger and the problem was this info below. Chargers made for operational readiness, or standby mode, often let the battery voltage drop to 4.00V/cell and recharge to only 4.05V/cell instead of the full 4.20V/cell (Mine is a Solar 18V 100W) Now I wondered how to balance cells that don't get to full 4.2 volts and man you solved this problem for me!
Is there any way this BMS is taking the energy from main contacts and charging the unballanced cells when battery is discharging? I am using an active 4S balancer made by REC-BMS and it is working this way. It is also discharging higher charged cells to battery main contacts, when the battery is charging.
With a super capacitor bank, you'll only get a significant imbalance during rapid charging or discharging, and there is more than a minor difference between the capacitors.
I've got a few of these from 4s to 16s but my 13s blew its IC between cell 3 and 4, measured the resistance on these cables and got 10 ohms, seen a few videos of these bursting into flames on first use, build quality variable, so now I'm trying to identify the IC so I can replace it, hoping to reverse engineer it and make my own.
Hi Julian, I know this is a bit delayed but quick question, If you had those super capacitor connected to a battery pack (LIFEpo4) would they discharge the batteries? I;m just about to make a battery pack and was thinking of adding some supercaps but trying to decide whether to connect on the batteies or after the switch
You can't test the balancer while you're charging at the same time! Please do the experiment again and measure the currents on each wire to see what is really happening! I got the 7S and a 16S versions for my packs and seem to work OK, but current seems to be much lower than 1.2A. I'm still not convinced it's charge pumping, but I don't have enough ammeters and voltmeters to know for sure.
Julian, if I bought a 6S Active Balancer BMS would I be able use part of the BMS, say use it on only 3 or 4 Li-ion cells if required? If I could it would save buying lots of different Active Balancer BMS’s
I think this is going to solve a problem I have with one of my 3S tool batteries. It's a dumb battery with no balancing and as a result over a few charge cycles one of the cells gets out of sync with the others and then the battery capacity is severly reduced as it doesn't charge properly and cuts out in the tool. At the moment I have to open the battery and manually balance the cells. I think I could add in the wires for this board and then let the board do this for me. Now to find it at a good price.
I have worked out I can fit this into my battery charger using the monitoring pins built into the battery. Obviously not to be used while battery is charging but I can use it to balance afterwards. Going to make it removable by using a USB as it has the 4 pins/wires I need for a 3S board.
Hi Julian and all. Can we really call this BMS ? It's only balancing the cell, but doesn't seem to do any overvoltage or undervoltage protection of each cell ! Which is very important for Li-ion battery, if not most important! With that board, you can argy that all cells are balanced at each time (which is far from true in case of defective cell or problem on the battery pack like broken spot-weldded connection, 1.2A balancing current would never fix a 10, 20 or even more amp of your charging device or your fed device) and thus, manage the entire pack voltage for over and under voltage, but I don't think it's the good way to do it, actually, I'm pretty sure it's not. I would be interested of what you think.
Hm, I wonder how much rf noise that device generates. I think I'm going to buy a couple just to try but the RFI would restrict the use to cases where that won't matter.
Julian thanks for sharing,the question is ! as literally the word balancing means : if using a DVM and testing the voltage across each cell it should show equal voltage after a certain time wouldn't it ? any heat builds up during balancing? it looks like an opto-isolator was used to activate the voltage sensing comparators op-amps i suppose.cheers mate.
I had a idea. Could it be possible to make a circuit that connects from one extra battery and walks around to the other cells? Basically as it hits the higher voltage cells the extra cell would draw some charge then as it moves to lower cells it releases charge.
I can't see why it should be quandary about whether this device works as boost or buck converter. To me it is obvious, it is a buck one. It takes the voltage from a higher cell and bucks to to the undercharged cell. The 0.03V difference is simply the margin at which bucking stops. The logic of the IC is quite clever as it is, to make it boost or to be in the "any cell to any other cell" configuration would make it prohibitively expensive.
No, it's a buck/boost topology. To transfer a decent amount of current between two similar potentials (this stops at 30mv difference) you have to use a circuit that can boost.
Nvm it does work without charging or discharging. You just have to be careful when plugging it in. Either go in fast or make sure the -B pin touches first. Also loose connection causes the board to short out in like a second. Make sure those solder joints r good
If you check item/33060735605.html on Ali, you will see there is a small usage video. They show how you can use the 16 board with just 5 LiIon cells, and as long as the polarization is okay, it does not matter where you connect the array of cells. On LiIon it did 0.36 A. You should really look up that video. (I am not endorsing any of it, I want to be informative, that's all). Nice find! This active BMS. How ever, your charging circuit will still overcharge cells, if the charging current is higher than the BMS can distribute. In other words, you make it mandatory to charge all cells with a maximum current equivalent to what can be dissipated. Uh, right. Things do get complicated now, you can not rely on the maximum (outer) voltage otherwise.
For reverse engineering you could take all the parts off and soak the board in aceton. Either it will desolve the whole solder mask, or it makes the traces better visible. If you got a second one give it a try.
When I've the money spare I need to re-build a battery pack for an old power tool. I've some cells just need the electrical gubbins like this. It'll be a big jump from Ni-Cad to Lithium.
Shouldn't it be balancing also without charging, even while discharging ? This would be great if one cell inside a bigger pack drops prematurely while under load.
Does not this module decrese the lifespan of the batteries quicker? Passive balancing takes the energy from one battery only, contributing to its charging/discharging life cycle. But when you are charging one battery by another battery, you decrese the lifespan of both batteries.
So it's like a bulletproof battery, you can connect to any number of it's cells and it'll just take it. If pulling under 1.5 amps you could debatably use this *instead of a buck regulator,* by just choosing how many cells you pull from. This is wild, every multicell battery out there will now be able to output multiple voltage ranges instead of locked to only one. Does this also mean you can *charge just one cell* - and that one cell will then be used to charge all other cells in the pack? So you no longer need a high voltage supply to charge this battery. It can effectively charge as if the cells are in parallel instead of series.
Yeah it's early days, but think of the next version, think of the modifications. I'm hoping it might be cost effective to beef it up. In TV shows & video games, technology is often oversimplified to an comical extent where if you just touch a battery onto ANY power source it'll somehow magically recharge it, everything interfaces with everything. Blissful. edit: aww, on reading more it seems the current goes through the chip, so the chip itself will always limit to 2A max (so says datasheet).
@@JulianIlett probably works great if your use case is somewhat like this: you have a high voltage high power application that requires batteries, but you also need a small current at a lower voltage for, say, some monitoring device. current sensors, wifi connectivity and somesuch. while you could put a buck converter to power those, and it might even be reasonably efficient for the designed load, that wouldn't also give you the benefit of active balancing.
Should be able to...Two 12S modules should do the trick... That's what Julian was referring to at the end of the video were he mentioned being able to cascade them.
@@pfeerick Cascading them, I think you need to overlay one of the cell with the 2 BMS, so for 24 S you would need at least 12s an 13s BMS (or 8s ans 17)
@@Llop66 Yeah, I can see how that might be needed, otherwise you'd potentially end up with two 'banks' within the example 24S configuration... hadn't thought of it that way... thanks! :)
Do you really need a buck converter? it could be the case that cell 1 is being charged with a higher voltage (lets say 2x 4.2 volts) and for cell 1 to charge cell 2 it could be 4.2 volt -> 4.1 volt and the bigger the voltage differences the bigger the charge current with a limit of 1.2 amp.
I've been thinking of replacing the dead NiCad cells in an old 12V cordless drill with three 18650s and this board would make it possible but at £10 it would double the cost of the repair and I would need to buy a charger capable of charging three cells in series. This is not financially sensible, it would cost more buying than a new and better drill. So my solution is to fit a connector to the battery pack which connects to both ends of the three cells. Then I use a single cell charger (that I already have) with a connector that puts the three cells in parallel and when in use I fit a dummy connector that puts them in series. I would still need to fit a 3S protection circuit in the pack but they cost peanuts. Three series 18650s are nominally 11.1V and would have about three times the capacity of the original NiCads.
If anyone else is thinking of doing this then remember that you need to buy high current versions of the 18650 and it helps to buy them with tabs. It's not a good idea to solder wires onto any type of battery.
You were turned charger on all the time. So you cannot be sure that balancer is doing anything. It would behave same even without that balancer in this setup.
mmh that balancer should be given the time to equal out cells 3 and 2 and then i would expect the voltage on cell 2 to differ from cell 1 so it should light out first the left led for some tome and then the right one. but to be honest i guess this thing was a bit slow for my taste. i wouldve wanted to see it equal out these cells a bit faster also it wouldve been nice to see to which voltage you discharged that one cell with your h7 car bulb. apart from that did you already start figuring the problems with your spot welder? and your featured in a hackaday post on that maybe its worth a read (if for nothing else then at least for the links to other projects of the same kind)
Yeah, I'm fairly certain the problem with Supercap spot-welding is the very fast voltage drop (exponential fall into a fixed resitance load). This is where a battery works and a supercap doesn't. I like the simplicity of Dark Kevin's 12V car battery and hand-timed solenoid setup :)
i doubt its doing what it claims, why not attach a voltmeter between each lead from bms to the cap and see if polarities change while balancing, im assuming it will balance in one direction rather than other way round as well
@@xbipins this chap seems to think it is an eta3000 www.beyondlogic.org/review-li-ion-lipo-lifepo4-lithium-battery-active-equalizer-balancer-energy-transfer-board/
I do like your chanel.. Well there are companies who make several kWh units from super kondenzators.. But price is just robbery (very green environmental). Anyway you can make better and you have the knowledge for proper storage from super-kondenzator.. Like 48V for your solar system.
The audio change from the commentary on on your workbench to the commentary on the eBay page didn't "burst out" as energetically as usual, please resume the usual explosive switch to eBay commentary on future videos. Enjoyed this video and I intend to make a purchase and experiment with some Wickes cells myself also. Cheerio.
Now to bad it doesn't only do this when unplugged and then stop each cell when done charging so they're not doing a balancing act, faster charge. like the TP4056 does for me.
Or there's the brute force method: Install a bunch of relays to put all the cells in parallel, which would balance them quickly, then put them back in series. The only drawback is that they'd have to be offline for charging. (For extra credit, do the same thing with mosfets and an Arduino.)
they probably have bigger self-discharge current than batteries, so they might be useless for long-ish term storage (i might be wrong on that one), but the higher charge and discharge current might make them ideal as buffers for intermittent high-current load/generators. what is your use case?
@@jacquesb5248 possibly. If the charge is done properly. Supercaps are way more sensitive to overvoltage than, say, lead batteries. It might be cheaper to A verify that your current batteries are actually good B just add more batteries. Maybe your problem is insufficient capacity. You should determine if your problem is energy or power. Capacitors have more instant power but they are smaller capacity and higher self discharge. It might very well be that one problem is disguised as another. You might have a too high initial current draw which damages your batteries and makes them lose capacity. In that case you should buy fresh batteries and put more in parallel and/or a small capacitor bank in parallel with it. Or you simply don't have enough capacity in your batteries to last enough time. Then all you have to do is put more batteries. You have to characterize your setup: internal equivalent series resistance, parasitic power draws, self discharge rate (equivalent internal parallel resistance), peak power consumption, average power consumption before anyone could with any reasonable confidence give you advice.
i very much doubt it can transfer 1.2A. the battery balancers that balance at all voltages have the disadvantage in so far that you need perfectly matched cells. otherwise it will try to transfer power all the time in the lower voltage cell but then has not time to discharge that cell again and then in fact creates cell unbalance. this happened to me. a cell balance system should only balance in the satiated area (almost full). it therefore has to be adjustable because there are that many different lithium batteries.
So, what happens if you drain the middle “cell” (here, a capacitor)? Which one does it transfer the energy out of, 1 or 3? Okay, never mind. I want huge flames... where’s my BoomBoxDeluxe... ?
The price of these still haven't come down and I don't know why. They are still about 10 quid from aliexpress including P+P. Considering the components involved, these should be as cheap as chips by now.
@@Ziplock9000 That's good to hear. It's a shame no-one in the UK is selling them, I always prefer to buy from a local seller even if it does cost me slightly more as it's so much easier to get a refund if something goes wrong.
i invest for some time an idea actually triggert by you julian with the joule thief to do this. But quickly ended with the single direction ernergy taransfer limit. But the breaktrought for me was an idea to you standard available components, and i do my balancing with class D mini audio amplifier. PAM8403 is best. Input grounded so its cold against AC and the internal DC is reference supply/2. Power for PAM8403 for two super caps from 0 to 5 or 5.4V and the the decination filter at output works fine to transfer energy between two super capacitors. With a second PAM8403 its then possible by overlap to build a 3s balancer. does work fine even into 1A transfer current, which is for balancing with not wasting into heat more then efficent. Standard balancer just burn ~100mA. PAM8403 boards are ready and need only very little modification. the inductor can be taken or must be added i tested with 10uH works fine
i want to agree with OP as the specs suggest that 100mv is needed to start activity and it will terminate at 30mV difference. if only using Boost, that would also work, as only current needs to be transferred......therefore i cant really see a need for extra complexity
@@mekuranda You don't have to guess, just look at the datasheet and the various white papers on this method and if you have some electronics background you will clearly see it's a classic buck boost circuit. Some of them use Ćuk converters which is another type of buck/boost topology. Sit down with a pen and paper for a while and you find it's not actually possible to implement a single inductor buck converter topology that can do what this does.
@@ferrumignis Thanks for your comments - when I made mine I was in front of the TV typing on a small remote keyboard - so it was just a casual comment. What is said in the data sheet is one thing, and it could do both buck and boost - I was thinking with out fully knowing what is really going on in the device - I tend to become sceptical about how something operates in a gut sense when the no.s don't stack up - i.e. the 100mV and 30mV thresholds - in all buck boost topologies I have ever played with and with modern gain and comparator blocks - the thresholds are amazingly loose - in a potentially clever device that could be used in up to 100s systems - the cumulative errors would limit this. If the thresholds were an order of magnitude or more smaller - it could find its way into power walls of larger household systems. I don't have the ability to know what the designer of the chip was thinking or if there are simplifications because of some component (die level) choices or limits to prevent a better spec - but have been caught many times in the past assuming what is written or even schematics presented in IC's not actually close to whats inside - hence often responsible IC vendors have a disclaimer of sorts to say "equivalent cct" useful for simulations or even just simplifications to gain a sense of "how it might work" in your application. I suspect this is a really simple device used in a creative way and I will as you suggest watch this space and revisit the datasheets of this and other devices - I don't often comment on RUclips engineering articles - as so often people make comments about things they are not familiar with - instead I found this product/component thought provoking and mysterious and the original poster was not the only one who was very adamant that it was this or that - must have just slipped into a cheeky mode for me to say - he could be right - as so many before him had said all kinds of opinions as pseudo facts!
I'm thinking to replace my motorcycle battery with six supercaps. But now I see that one lightbulb can empty a cell that quick......... I dont know if I still want to execute that plan. Lets start learning about calculating farads to mAH :D
I'd only do that if my motor cycle still used a kick starter and I was sure I'd never want to use the lights with the engine turned off, otherwise the supercap pack would run out of energy too quickly to be of use in an emergency.
nice video, but i think you're setup is a bit flawed. you are not really showing that it is "moving" current from one cell to another. you are charging at the same time and you are not even measuring the individual voltages on the cells and not measuring the amps. it might as well that this balancer is simply "burning" current on the cell(s) with the highest voltage
![[SFM] Risky Recital](http://i.ytimg.com/vi/RzNkY1_Nk3o/mqdefault.jpg)
I got the 7s version of this and have tested it for 2 months. Works great so far. However, we need a version 2 of this because it only monitors differences of adjacent series. We need one that takes an average of all 7s and tries to bring every series to the average voltage otherwise what happens is that at 0.03v accuracy multiply by 7 = 0.21v. In theory, the 1s (first series) can be at 4.10v and the 7s can be at 3.89 (-.021v) and this balancer will not care. This will become worst with a 14s pack and so forth.
It would be nice if you used a clamp meter to actually measure the current, rather than spending a lot of time speculating...
Or at least voltmeters on the 3 caps!
Tried 2 boards in parallel to see if it will multiply its balancing current
See it here.
ruclips.net/video/2S0wMsFcUjg/видео.html
Clinton Coker heres a quick timelapse on its energy transfer
ruclips.net/video/UQinTqFLb68/видео.html
Would have thought this was an ideal opportunity to get out 4 ammeters, looks forward to the reverse engineering, and hopefully a rebuild with capabilities of 10 amps :)
yeah he could have even pulled out his 4x Ryobi DVM
I have one AB for 16S and it sits. I never thought it can go that low on voltage. Since I am building 6S SC pack now I can use this balancer finally. Great video. Thanks.
The circuit is similar to a synchronous buck switcher. A synchronous buck converter has an active MOSFET for rectifier as well as normal coil charge MOSFET switch. Because it has two MOSFET's to series coil it can buck in either of two cells direction. The I.C. measures which one of the two cells is higher and buck transfers from higher to lower voltage cells. Multiple IC's overlap every two cells so it can bucket-brigade charge transfer up and down a series stack of cells.
It actually worked better for you then I expected for the 2.5v supercaps although you did not measure transfer current. Problem, which you eluded to, is as the cell voltage is lowered, the gate drive voltage to the MOSFET switches is reduced. This causes their ON resistance to go up reducing the buck switcher transfer current and creates higher switching losses.
Definitely want to see the lithium ion in action...to see how well it can handle an almost completely flat pack to full charge how close it maintains the cells till it reaches full charge
Might be a good way to safely charge a battery pack with multiple cells if it can actually maintain good balance from dead to full charge in all the cells, especially if there is a weak cell in the pack
That should work if you charge the pack at a current well below the balancer's transfer current.
Please buy a multimeter and stop guessing. Thank you. (found it interesting anyway)
@@appleejack A lot of S C manufacturers will use the same case to keep a standard form factor. The dimples take up interior space when using a lower value capacitor BUT keep the same outer diameter. Think of the dimples as filler material.
Mr. Ilett, I bought a 14S version with the intention of reverse engineering it for a much higher current transfer and can confirm that it does indeed squirt 1.2A when connected to Li-Ion batteries.
I've got a rough drawing of my work to date, if you want it.
Wow, MUCH more effective than traditional bms's. I like!
I'm going to get one for my 48v powerwall sized bank.
I wouldn't just yet. I've attached it to my 14S 80P powerwall and it takes forever to shift a 200mv difference. When Julian comes up with a 20A version, he'll make us powerwall chappies very happy.
@@peterpurpose ah thank you... I am assembling 80p packs so I appreciate the insight. My first 14 packs contain identical 2000mah cells that i've already capacity tested, so they should be pretty closely balanced in capacity... but when I expand I will be dipping into different cells, so a larger bms will be needed then.
Have you used a resistive bms? I would think even this stock would beat one of those aince they tend to do a wimpy 20ma draw or similar.
Have you used a resistive bms?
I have not, but my apc ups is so inefficient that I'd rather not waste the little British sun that we get.
@peterpurpose can you please post your drawing? Thank you!
That an interesting product for some niche cases where you get large unbalance and are in desperate need to save every bit of power you can. Often balancing difference with good cells is not that large and passive systems do not waste that much energy.
Indeed. I made a 4S lifepo4 battery pack from new cells (all same batch) that I was prepared to balance manually - about 50 charge/discharge cycles later I've never had to balance them (never been more than 0.01v different at top or bottom of charge). Interesting.
I think this module is interesting in the case of refurbished cells in a pack. Given that this kind of cells have very different characteristics, they will get out of balance pretty soon
That board would be fun to play with. You could use a voltage divider and have it drive a relay or a different boost board externally with higher voltage cells or even 12 volt batteries in series.
Put a Volt Meter on each capacitor and you'll see it's not boosting any voltages. It is bucking all voltages. So it takes the higher voltage of 2 cells/caps, and bucks it down to the lower cell/cap. With the inductors, it must do it using pwm, which makes sense because it needs to be decoupled when transferring the energy, otherwise a short will occur.
So, when you pull the energy from the center cap, the device will then buck the voltage from cap 1 down to cap 2, and buck cap 3 down to cap 2, until cap 2 reaches the voltage of caps 1 and 2.
(This is how I understand it works. Altho, I could be wrong on this setup and would love to see how it really works)
A neat trick I'd like to see tho, is doing something really wildly extreme on the votlages. Make cap 1 at 2.3V, cap 2 at 2.0V, and cap 3 at 1.9V, and see what the unit does. Will it start transferring from cap 1 to cap 2, as well as transfer from cap 2 to cap 3?? Will it go sequential bouncing back and forth? will it fry itself????
Wrong way to look at it. The device uses a Buck/Boost topology (check the datasheet and the various papers on on these balancers), and whilst the output voltage is clamped by the cell being charged, to get a decent amount of balancing current into that cell you need something capable of generating voltages higher than the cell.
Heres a quick test on its enrgy transfer.just to show if it really transfers energy
ruclips.net/video/UQinTqFLb68/видео.html
I'm currently waiting for a 3S version to arrive, for balancing the packs in my current Solar Energy Accumulator (often known as solar generator)project.
These modules look very clever, and more efficient than resistive balancing the cells.
Finally I have always felt that over voltage balancing by burning off excess voltage through resistors was just wasting your already stored energy. At least this uses that energy to charge your lower cells.
Me too - I feel the same :)
What an interesting little module.
You made a comment at the end of your LiFePO4 video which made me think you might be testing this module too :)
Heres more interesting, multiplying the balance current by connecting parallel boards.this test uses five of this cheap 3s boards.
ruclips.net/video/Kg8SeHJVsWY/видео.html
Good data there Julian. I use active balancers from Deligreen, constant functions to bring or maintain a lithium-ion pack to on or below 10ma up to 8amps per cell 4.2v max.
Honestly, I don't think I have ever seen a balancer circuit actually work the way we all want it to work. It's all about ohms law, very small voltages / small resistors = very small currents. I think you would not of seen any difference between a pack with the balancer and a pack without the balancer. You would have to have a bad cap or cell in the pack to see that balancer do anything noticable. Interesting video, I like your common sense approach and the fact that you don't rehearse before doing the video.
This would be more clear if you were not also charging the stack at the same time this balancing board is supposed to be trying to help. How about getting 3 volt meters and repeating the experiment, and leave the charger off? I can't tell if it's this magical board doing the balancing, or your existing protection devices with this board just reporting a voltage difference?
Take a look at the ALD8100 super capacitor balancing mosfets
Yes, may be dandy to pull 12v from a 24v system for limited use. Sure would take a long time correcting it's self at those low transfer rates.
The purpose is not to draw 12 volts from a 24 volt battery as many people erroneously believe and constantly erroneously post. The purpose is to lengthen the lifespan of any battery and increase it’s effective amp hours because balancing allows you to get more out of the fuller cells because your BMS doesn’t kick on from early polarity reversal in a less full cell. This thing is amazing for a 12 volt battery, or anything that uses more than one cell in series. (Series batteries are dangerous if a cell is empty when the other cells are highly charged masking the empty cell)
Thanks jullian, I got the 7S version of this, only thing was lacking of this module is there wasn't any proper review. now we have this thanks
Will Prowse reviewed them a few weeks ago - he was initially impressed, but then suspected they weren't charging low cells and instead bleeding. Need Julian to do a proper test!
@@ahaveland didn't saw that review. hope jullian comes with a proper test on these modules
Very nice. Do make the lithium version please. Would be cool to measure the current going through the individual leads. I've been looking for a cheap active balancer for ages. The only one downside is these will hide a dying pack as you won't notice it sagging.
I tested this module and the current depends on voltage difference. Grather the difference bigger the current it transferrrs from one to other cell. Curent is linear to voltage difference.
So it may start at 1.2 Amps, but it will fall rapidly from that value.
@@JulianIlett yes, at a difference of around 1V it will be 1A maby less . And as the difference drops drops the amperage too. The device gets pretty hot at 1.2A so be careful.
How about 2 parallel boards to multiply its balancing current.heres a test made of it.
ruclips.net/video/2S0wMsFcUjg/видео.html
Most types of batteries have difficulties when configured in parallel (same voltage, increased amperage). It is common to have a cell that isn't staying at full voltage (what it's voltage would be if not in parallel). This device enables automatic switching in a parallel circuit to ensure your batteries stay balanced.
i think you are a bit confused about something?
I got 4 of these balancers on eBay to use on my 14s Lithium ion battery pack. First one burnt with smoke when I plugged in. Second one kind of worked. However in a 14s pack, with minimal 0.1V difference for the balancer to kick in, the worst case scenario there can be 1.4V difference in voltage between cell with minimum and maximum voltages. After all I went ahead with a capacitor based balancer with better sensitivity.
In your worst case scenario 1,4v. (In theory) That means that the best cell triggers the BMS at 4,2v so the charger stop. And the worst cell is at 2,8v.
That will never happen in real life. Liion are empty at 3v so the charger never charge and your battery pack have no energy.
This is what I was Talking about a while back. Transferring the power from one to add another that needs a boost.
Well I'm still going to continue with my 'cell to pack' idea using the inverter modules :)
So, with 17 cells, and one in the end very slowly losing charge you'd eventually get somewhere between 0.48 and 1.6V difference between highest and lowest cell, as balancing stops at 30mV, but doesn't start, and therefore restart until 100mV difference?
Are they single wound inductors? Couldn't see enough detail of the PCB
Yes, tiny SMD inductors marked 1R0 (1uH?) with two pads down on the PCB.
@@JulianIlett 1R0 = 1 Ohm wire wound bleed resistor masquerading as an inductor in marketing?
Definitely inductors. If these were simple bleed circuits, there would need to be 3 of them (1 per cell).
Your video helps us to know basics better.
Thank you very much
I learned a lot and you helped me make an informed decision when ordering BMS for my lithium 18650 project.
REASON!. I wanted to make a 4S Li-Ion standby charger and the problem was this info below.
Chargers made for operational readiness, or standby mode, often let the battery voltage drop to 4.00V/cell and recharge to only 4.05V/cell instead of the full 4.20V/cell (Mine is a Solar 18V 100W)
Now I wondered how to balance cells that don't get to full 4.2 volts and man you solved this problem for me!
Is there any way this BMS is taking the energy from main contacts and charging the unballanced cells when battery is discharging? I am using an active 4S balancer made by REC-BMS and it is working this way. It is also discharging higher charged cells to battery main contacts, when the battery is charging.
With a super capacitor bank, you'll only get a significant imbalance during rapid charging or discharging, and there is more than a minor difference between the capacitors.
I've got a few of these from 4s to 16s but my 13s blew its IC between cell 3 and 4, measured the resistance on these cables and got 10 ohms, seen a few videos of these bursting into flames on first use, build quality variable, so now I'm trying to identify the IC so I can replace it, hoping to reverse engineer it and make my own.
I would have expected the board to come with mounting holes. What would be the best way of fixing it? A clamp? Hot glue? Dangling in the breeze?
How about this test, 2 boards in parallel, seeing if doubles the balncing current
ruclips.net/video/2S0wMsFcUjg/видео.html
easy, it's using a 2nd fet in place of the diode in the boost, circuit will look like a 1/2 bridge. I sold one like this in the '80s
Good work. This in conjunction with some smart electronics to meassure whats going on and when to start stop this would be killer for sure
Hi Julian, I know this is a bit delayed but quick question, If you had those super capacitor connected to a battery pack (LIFEpo4) would they discharge the batteries? I;m just about to make a battery pack and was thinking of adding some supercaps but trying to decide whether to connect on the batteies or after the switch
You can't test the balancer while you're charging at the same time!
Please do the experiment again and measure the currents on each wire to see what is really happening!
I got the 7S and a 16S versions for my packs and seem to work OK, but current seems to be much lower than 1.2A. I'm still not convinced it's charge pumping, but I don't have enough ammeters and voltmeters to know for sure.
That's a lot of ammeters! I may put the scope on the connector and look for evidence of a switch between buck and boost modes.
@@JulianIlett That would help - don't have to do all of the wires at the same time!
On LTO (2.5v) it's charging at 35ma to 65ma
When using LiPo batteries, Is it necessary to use a LiPo charger with these active balancer boards, or would a fixed voltage be OK? Thanks
Julian, if I bought a 6S Active Balancer BMS would I be able use part of the BMS, say use it on only 3 or 4 Li-ion cells if required? If I could it would save buying lots of different Active Balancer BMS’s
Hi Julian Ilett
Can you please explain the circuitry involved in the board
Google "Buck boost cell balancing"
is there a video on you building the super-caps and what are the things on the bottom of the caps?
I think this is going to solve a problem I have with one of my 3S tool batteries. It's a dumb battery with no balancing and as a result over a few charge cycles one of the cells gets out of sync with the others and then the battery capacity is severly reduced as it doesn't charge properly and cuts out in the tool.
At the moment I have to open the battery and manually balance the cells. I think I could add in the wires for this board and then let the board do this for me.
Now to find it at a good price.
I have worked out I can fit this into my battery charger using the monitoring pins built into the battery. Obviously not to be used while battery is charging but I can use it to balance afterwards.
Going to make it removable by using a USB as it has the 4 pins/wires I need for a 3S board.
Hi, do you know what kind of connector the board has? I'm struggling to find that information.
Thanks!
Hi Julian and all.
Can we really call this BMS ?
It's only balancing the cell, but doesn't seem to do any overvoltage or undervoltage protection of each cell ! Which is very important for Li-ion battery, if not most important!
With that board, you can argy that all cells are balanced at each time (which is far from true in case of defective cell or problem on the battery pack like broken spot-weldded connection, 1.2A balancing current would never fix a 10, 20 or even more amp of your charging device or your fed device) and thus, manage the entire pack voltage for over and under voltage, but I don't think it's the good way to do it, actually, I'm pretty sure it's not.
I would be interested of what you think.
Looks very modular. I would really like to be able to breadboard the modules. Please reverse engineer, Julian.
See pinned comment :)
Hm, I wonder how much rf noise that device generates. I think I'm going to buy a couple just to try but the RFI would restrict the use to cases where that won't matter.
Julian thanks for sharing,the question is ! as literally the word balancing means : if using a DVM and testing the voltage across each cell it should show equal voltage after a certain time wouldn't it ? any heat builds up during balancing? it looks like an opto-isolator was used to activate the voltage sensing comparators op-amps i suppose.cheers mate.
I am confused, You called them supercapacitors and the article says Lithium Ion packs. Which are they?
Its possibly click bait.
The balancer is designed for use with lithium battery packs, but he's using it with super capacitors.
I had a idea.
Could it be possible to make a circuit that connects from one extra battery and walks around to the other cells?
Basically as it hits the higher voltage cells the extra cell would draw some charge then as it moves to lower cells it releases charge.
I cannot find it anywhere, but does this have a discharge/recharge cuttoff?
thanks for showing this... I've been considering getting one.
Could u daisy chain then on a big battery to balance the whole battery?
I can't see why it should be quandary about whether this device works as boost or buck converter. To me it is obvious, it is a buck one. It takes the voltage from a higher cell and bucks to to the undercharged cell. The 0.03V difference is simply the margin at which bucking stops. The logic of the IC is quite clever as it is, to make it boost or to be in the "any cell to any other cell" configuration would make it prohibitively expensive.
No, it's a buck/boost topology. To transfer a decent amount of current between two similar potentials (this stops at 30mv difference) you have to use a circuit that can boost.
I read somewhere you have to run power through the pack for this to work? I'm getting mine today hopefully it'll work for what I need.
Nvm it does work without charging or discharging. You just have to be careful when plugging it in. Either go in fast or make sure the -B pin touches first.
Also loose connection causes the board to short out in like a second. Make sure those solder joints r good
tested same balancer, it failed in my case. performed 4 tests and it was not able to bring cells to promised 30mV cell diff..
Does it only work with cells in parallel or does it only work properly with cells in series?
This is brilliant! I wonder what the thermals of the balancer board look like when you're putting a load on just one cell, for example? Thanks Julian!
If you check item/33060735605.html on Ali, you will see there is a small usage video. They show how you can use the 16 board with just 5 LiIon cells, and as long as the polarization is okay, it does not matter where you connect the array of cells. On LiIon it did 0.36 A. You should really look up that video. (I am not endorsing any of it, I want to be informative, that's all).
Nice find! This active BMS. How ever, your charging circuit will still overcharge cells, if the charging current is higher than the BMS can distribute. In other words, you make it mandatory to charge all cells with a maximum current equivalent to what can be dissipated. Uh, right. Things do get complicated now, you can not rely on the maximum (outer) voltage otherwise.
So is this board not the same as what we find in balanced power tool batteries?
Don't your protection boards essentially "balance" without the new board?
yes, but those do it by wasting the extra energy. This new board here doesn't waste the excess energy, that's why it's interesting.
@@roidroid Not only that but a regular BMS only balances when the cells voltage is at the maximum. This module balances all the time !
For reverse engineering you could take all the parts off and soak the board in aceton. Either it will desolve the whole solder mask, or it makes the traces better visible. If you got a second one give it a try.
We need clive to make a video on this and go in depth
Not sure what "Eighter" is?
@@goosenp solved
When I've the money spare I need to re-build a battery pack for an old power tool. I've some cells just need the electrical gubbins like this. It'll be a big jump from Ni-Cad to Lithium.
I have the 7s version of this board, was really keen to see what chip is used but couldn't make it out.
See ICT Dept comment below - review, data sheet, schematics, the lot :)
Shouldn't it be balancing also without charging, even while discharging ? This would be great if one cell inside a bigger pack drops prematurely while under load.
Does not this module decrese the lifespan of the batteries quicker? Passive balancing takes the energy from one battery only, contributing to its charging/discharging life cycle. But when you are charging one battery by another battery, you decrese the lifespan of both batteries.
So it's like a bulletproof battery, you can connect to any number of it's cells and it'll just take it. If pulling under 1.5 amps you could debatably use this *instead of a buck regulator,* by just choosing how many cells you pull from. This is wild, every multicell battery out there will now be able to output multiple voltage ranges instead of locked to only one.
Does this also mean you can *charge just one cell* - and that one cell will then be used to charge all other cells in the pack? So you no longer need a high voltage supply to charge this battery. It can effectively charge as if the cells are in parallel instead of series.
Well, sort of. All that stuff is theoretically possible, but it would have to be done at low current.
Yeah it's early days, but think of the next version, think of the modifications. I'm hoping it might be cost effective to beef it up.
In TV shows & video games, technology is often oversimplified to an comical extent where if you just touch a battery onto ANY power source it'll somehow magically recharge it, everything interfaces with everything. Blissful.
edit: aww, on reading more it seems the current goes through the chip, so the chip itself will always limit to 2A max (so says datasheet).
@@JulianIlett probably works great if your use case is somewhat like this:
you have a high voltage high power application that requires batteries, but you also need a small current at a lower voltage for, say, some monitoring device. current sensors, wifi connectivity and somesuch.
while you could put a buck converter to power those, and it might even be reasonably efficient for the designed load, that wouldn't also give you the benefit of active balancing.
I have 24S - is there any way how I can combine multiple of this to use it for 24s?
Should be able to...Two 12S modules should do the trick... That's what Julian was referring to at the end of the video were he mentioned being able to cascade them.
Klemen Zhivko its possible, just overlap the last cell connction to the 1st cell connection of the other board
@@pfeerick Cascading them, I think you need to overlay one of the cell with the 2 BMS, so for 24 S you would need at least 12s an 13s BMS (or 8s ans 17)
@@Llop66 Yeah, I can see how that might be needed, otherwise you'd potentially end up with two 'banks' within the example 24S configuration... hadn't thought of it that way... thanks! :)
Do you really need a buck converter? it could be the case that cell 1 is being charged with a higher voltage (lets say 2x 4.2 volts) and for cell 1 to charge cell 2 it could be 4.2 volt -> 4.1 volt and the bigger the voltage differences the bigger the charge current with a limit of 1.2 amp.
Very interested to see more measurements and a reverse engineer on this one 🙂
I've been thinking of replacing the dead NiCad cells in an old 12V cordless drill with three 18650s and this board would make it possible but at £10 it would double the cost of the repair and I would need to buy a charger capable of charging three cells in series. This is not financially sensible, it would cost more buying than a new and better drill. So my solution is to fit a connector to the battery pack which connects to both ends of the three cells. Then I use a single cell charger (that I already have) with a connector that puts the three cells in parallel and when in use I fit a dummy connector that puts them in series. I would still need to fit a 3S protection circuit in the pack but they cost peanuts. Three series 18650s are nominally 11.1V and would have about three times the capacity of the original NiCads.
If anyone else is thinking of doing this then remember that you need to buy high current versions of the 18650 and it helps to buy them with tabs. It's not a good idea to solder wires onto any type of battery.
You were turned charger on all the time. So you cannot be sure that balancer is doing anything. It would behave same even without that balancer in this setup.
mmh that balancer should be given the time to equal out cells 3 and 2 and then i would expect the voltage on cell 2 to differ from cell 1 so it should light out first the left led for some tome and then the right one. but to be honest i guess this thing was a bit slow for my taste. i wouldve wanted to see it equal out these cells a bit faster also it wouldve been nice to see to which voltage you discharged that one cell with your h7 car bulb.
apart from that did you already start figuring the problems with your spot welder? and your featured in a hackaday post on that maybe its worth a read (if for nothing else then at least for the links to other projects of the same kind)
Yeah, I'm fairly certain the problem with Supercap spot-welding is the very fast voltage drop (exponential fall into a fixed resitance load). This is where a battery works and a supercap doesn't. I like the simplicity of Dark Kevin's 12V car battery and hand-timed solenoid setup :)
Hi. Thank you so much for this video. Can you show how to cascade them, for like a 30S?
And can these boards be paralleled, to have higher current transfer rates?
i doubt its doing what it claims, why not attach a voltmeter between each lead from bms to the cap and see if polarities change while balancing, im assuming it will balance in one direction rather than other way round as well
is the chip this one www.ablic.com/en/doc/datasheet/battery_protection/S8209B_E.pdf
@@xbipins this chap seems to think it is an eta3000 www.beyondlogic.org/review-li-ion-lipo-lifepo4-lithium-battery-active-equalizer-balancer-energy-transfer-board/
reasonably sure they only transfer to the next cell (last to first) and not back? i would like to see schematics :)
I do like your chanel.. Well there are companies who make several kWh units from super kondenzators.. But price is just robbery (very green environmental).
Anyway you can make better and you have the knowledge for proper storage from super-kondenzator.. Like 48V for your solar system.
The audio change from the commentary on on your workbench to the commentary on the eBay page didn't "burst out" as energetically as usual, please resume the usual explosive switch to eBay commentary on future videos. Enjoyed this video and I intend to make a purchase and experiment with some Wickes cells myself also. Cheerio.
Now to bad it doesn't only do this when unplugged and then stop each cell when done charging so they're not doing a balancing act, faster charge. like the TP4056 does for me.
Or there's the brute force method: Install a bunch of relays to put all the cells in parallel, which would balance them quickly, then put them back in series. The only drawback is that they'd have to be offline for charging. (For extra credit, do the same thing with mosfets and an Arduino.)
Julian, what is the IC located this board?
It's the ETA3000. www.beyondlogic.org/review-li-ion-lipo-lifepo4-lithium-battery-active-equalizer-balancer-energy-transfer-board/
I looked at both eBay listings and couldn't find out how you set the voltages.
You don't, it just looks at relative voltage levels between cells and makes them match up. It's the BMS that sets the overall voltage level.
am pondering to use these super caps to replace garage 24V battery
they probably have bigger self-discharge current than batteries, so they might be useless for long-ish term storage (i might be wrong on that one), but the higher charge and discharge current might make them ideal as buffers for intermittent high-current load/generators.
what is your use case?
the batteries allways flat or don't last long then I cat open garage door
@@jacquesb5248 supercapacitors will probably be flat even faster.
@@gominosensei2008 dunno. but charge cycles way more?
@@jacquesb5248 possibly. If the charge is done properly. Supercaps are way more sensitive to overvoltage than, say, lead batteries.
It might be cheaper to
A verify that your current batteries are actually good
B just add more batteries. Maybe your problem is insufficient capacity.
You should determine if your problem is energy or power.
Capacitors have more instant power but they are smaller capacity and higher self discharge.
It might very well be that one problem is disguised as another. You might have a too high initial current draw which damages your batteries and makes them lose capacity. In that case you should buy fresh batteries and put more in parallel and/or a small capacitor bank in parallel with it.
Or you simply don't have enough capacity in your batteries to last enough time. Then all you have to do is put more batteries.
You have to characterize your setup: internal equivalent series resistance, parasitic power draws, self discharge rate (equivalent internal parallel resistance), peak power consumption, average power consumption before anyone could with any reasonable confidence give you advice.
i very much doubt it can transfer 1.2A.
the battery balancers that balance at all voltages have the disadvantage in so far that you need perfectly matched cells. otherwise it will try to transfer power all the time in the lower voltage cell but then has not time to discharge that cell again and then in fact creates cell unbalance. this happened to me.
a cell balance system should only balance in the satiated area (almost full). it therefore has to be adjustable because there are that many different lithium batteries.
You are great, you explain it so nice and clear, keep it up. What super caps you use?
Thanks :) They're 700F 2.5V Nippon Chemicon
So, what happens if you drain the middle “cell” (here, a capacitor)? Which one does it transfer the energy out of, 1 or 3? Okay, never mind. I want huge flames... where’s my BoomBoxDeluxe... ?
11:10
The price of these still haven't come down and I don't know why. They are still about 10 quid from aliexpress including P+P. Considering the components involved, these should be as cheap as chips by now.
Down to just over a fiver now.
@@caskwith Nice one. Good to see the prices come down. I did actually buy a couple of these when I posted and they seem to work fairly well.
@@Ziplock9000 That's good to hear. It's a shame no-one in the UK is selling them, I always prefer to buy from a local seller even if it does cost me slightly more as it's so much easier to get a refund if something goes wrong.
Anyone know what kind of connectors this board uses?
The 10S unit i've got uses a JST-PH style connector on 2mm pitch, if that helps.
i invest for some time an idea actually triggert by you julian with the joule thief to do this. But quickly ended with the single direction ernergy taransfer limit. But the breaktrought for me was an idea to you standard available components, and i do my balancing with class D mini audio amplifier. PAM8403 is best. Input grounded so its cold against AC and the internal DC is reference supply/2. Power for PAM8403 for two super caps from 0 to 5 or 5.4V and the the decination filter at output works fine to transfer energy between two super capacitors. With a second PAM8403 its then possible by overlap to build a 3s balancer. does work fine even into 1A transfer current, which is for balancing with not wasting into heat more then efficent. Standard balancer just burn ~100mA. PAM8403 boards are ready and need only very little modification. the inductor can be taken or must be added i tested with 10uH works fine
Super interesting device!
You're The Man Julian!
I think they only do buck conversion. They wouldn’t need to boost, imho.
They do need to boost, you can not transfer sufficient current between two similar potentials with a buck converter.
i want to agree with OP as the specs suggest that 100mv is needed to start activity and it will terminate at 30mV difference. if only using Boost, that would also work, as only current needs to be transferred......therefore i cant really see a need for extra complexity
@@mekuranda You don't have to guess, just look at the datasheet and the various white papers on this method and if you have some electronics background you will clearly see it's a classic buck boost circuit. Some of them use Ćuk converters which is another type of buck/boost topology. Sit down with a pen and paper for a while and you find it's not actually possible to implement a single inductor buck converter topology that can do what this does.
@@ferrumignis Thanks for your comments - when I made mine I was in front of the TV typing on a small remote keyboard - so it was just a casual comment. What is said in the data sheet is one thing, and it could do both buck and boost - I was thinking with out fully knowing what is really going on in the device - I tend to become sceptical about how something operates in a gut sense when the no.s don't stack up - i.e. the 100mV and 30mV thresholds - in all buck boost topologies I have ever played with and with modern gain and comparator blocks - the thresholds are amazingly loose - in a potentially clever device that could be used in up to 100s systems - the cumulative errors would limit this. If the thresholds were an order of magnitude or more smaller - it could find its way into power walls of larger household systems. I don't have the ability to know what the designer of the chip was thinking or if there are simplifications because of some component (die level) choices or limits to prevent a better spec - but have been caught many times in the past assuming what is written or even schematics presented in IC's not actually close to whats inside - hence often responsible IC vendors have a disclaimer of sorts to say "equivalent cct" useful for simulations or even just simplifications to gain a sense of "how it might work" in your application.
I suspect this is a really simple device used in a creative way and I will as you suggest watch this space and revisit the datasheets of this and other devices - I don't often comment on RUclips engineering articles - as so often people make comments about things they are not familiar with - instead I found this product/component thought provoking and mysterious and the original poster was not the only one who was very adamant that it was this or that - must have just slipped into a cheeky mode for me to say - he could be right - as so many before him had said all kinds of opinions as pseudo facts!
Pls show me diagram for connecting 6s balancer to 6sbms
I'm thinking to replace my motorcycle battery with six supercaps. But now I see that one lightbulb can empty a cell that quick......... I dont know if I still want to execute that plan. Lets start learning about calculating farads to mAH :D
I'd only do that if my motor cycle still used a kick starter and I was sure I'd never want to use the lights with the engine turned off, otherwise the supercap pack would run out of energy too quickly to be of use in an emergency.
should have discharged the pack then tried to charge the whole pack with 2.5v on one cap
I bought 1 of each of these balancing circuits, works great and only cost $395 USD. What a bargain.
Yeah ! ...been smokin' weed ?! Lol !
Real tranfer 1.2a?
Schematic drawings needed
www.beyondlogic.org/review-li-ion-lipo-lifepo4-lithium-battery-active-equalizer-balancer-energy-transfer-board/
nice video, but i think you're setup is a bit flawed. you are not really showing that it is "moving" current from one cell to another. you are charging at the same time and you are not even measuring the individual voltages on the cells and not measuring the amps. it might as well that this balancer is simply "burning" current on the cell(s) with the highest voltage
its a resistor balance board, it drains at 0.07amps, tested and confirmed, it is not a active cell balancer
I don't know why you're so surprised about the bidirectional current transfer. You already figured out how to do that with your Muppet project.
That was easier in that both chargeable devices have a common ground