How Daly BMS balances your cells and ... actually works!
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- Опубліковано 26 вер 2024
- That balancing problem of the Daly BMS did not leave me alone. I needed to know how it works and why so many people say it keeps their battery in balance. So I set up the biggest test environment ever 😎 and failed...
Does the Daly really only balancing the one cell with the highest voltage as Paul said? It would make sense and could explain why it is working at all. It would need to balance the cells over many many cycles though to have an effect.... or is there even more to it? We will unveil all secrets of the Daly BMS in this video!
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I love how Power Paul gets all the credit even though I told you this in my comment in your last video (Which you responded to!) :P Like I said before: Any BMS will only balance the cells that are above either the pack average or above the lowest cell voltage. No BMS is going to ever balance all cells at the same time. Because like you said, that wouldn't actually be "balancing". They only balance the high cells.
That said, you still don't want to set balancing to start at 3.2v, that is too low because you could end up pulling balance current when the battery is being discharged or at low state of charge.
3.33v should be the absolutely minimum balance start current to ensure that cells that are at a low SoC aren't balanced down even lower.
OK, ok, ok, you're right, you said this before it is true, sorry. All credit goes to you and not to Power Paul. He was wrong anyway 😂
But the Daly BMS only balances while it's charging anyway, so it will never drag the pack down to the individually set balance start voltage. This sort of feature is only really possible when it's incorporated into a BMS so it knows when there's charge current going in.
@@PowerPaulAu This comment makes no sense.
Let's say If I have a pack with 4 cells at that when (mostly) fully charged look like this:
Cell #1: 3.60v (102 Ah)
Cell #2: 3.65v (101 Ah)
Cell #3: 3.55v (103 Ah)
Cell #4: 3.45v (105 Ah)
At very high states of charge the BMS will be pulling current from Cell #2 because it's the highest cell. It's the highest voltage cell because it has the lowest capacity and thus hits 100% SoC faster than the other cells.
Now let's examine this same pack again at say around 30% SOC. Now the voltages would look more like:
Cell #1: 3.22v (102 Ah)
Cell #2: 3.21v (101 Ah)
Cell #3: 3.25v (103 Ah)
Cell #4: 3.27v (105 Ah)
Cell #4 now has the highest voltage because as the strongest/highest capacity cell it's voltage will remain higher as the pack approaches lower SoC.
Now say my MPPT is putting out 50 amps and my inverters are drawing 48 amps, so I have a very low charge current of 2 amps flowing into the battery.
This 2 amps will turn on balancing, and it will now cause the BMS to draw balance current balance from cell #4, which will actually work to unbalance the pack because it's cell #2 which reaches 100% SoC first when at high states of charge.
This isn't some imaginary scenario either. I have spent many hours testing what voltages work best to start balancing. I've encountered this exact scenario when testing balancing at lower voltages.
If you want to top balance you need to make sure you never draw balance current when the battery is at a low SoC. Saying "it only balances during charging" is not really a good excuse since the battery can (and is very likely to be) be at very low state of charge during charging.
@@JeremyAkersInAustin this post/video is just about how the Daly Balance circuit works. I think you're delving way too deep. As for my comment not making sense, that's ok, it's the fact of how it works, it's not up to me to make sense of it. If you want a better explanation, and you're that invested in it, I'd suggest you contact Daly and ask why they do it this way. Andy isn't asking why, he's showing what it does. And so am I.
I can see you're upset about not getting a mention earlier on, but if Andy mentioned everyone that comments or helps, his videos would go on forever and would be much less fun. He's mentioned you now, twice at least, so we can all move on.
As he has alluded to, there's more on this coming, so let's sit back and await some more findings. Just keep in mind, he's effectively reverse engineering a sealed black (and red) box with minimal test equipment and no real documentation. Things aren't always as they seem.
If you want to provide better information than he is, perhaps it's worth starting a channel of your own, anyone can do it now.
@@PowerPaulAu "this post/video is just about how the Daly Balance circuit works."
No, it's not *just* about that. He's *also* addressing the hundreds of comments he received telling him he needs to start balancing at 3.2v, which as I pointed out with a very easy to follow and understand example, can cause the Daly to unbalance your pack because it would allow balancing to occur in the lower and middle states of charge. Everyone should understand by now that balancing in the lower to middle states of charge regions of a battery can cause your pack to become unbalanced. The fact that the Daly only balances during charge doesn't change the physics of this. Charging (and thus balancing) would frequently occur during low and middle states of charge. There's a reason Daly asks you to set a balance start voltage because they don't expect you to balance the pack anytime a charger is connected. Since 3.2v is very close to fully discharged, setting balancing to start at 3.2v essentially means balancing would occur almost anytime charge current is detected at almost any state of charge.
"I can see you're upset about not getting a mention"
Huh? I was in no way upset and I absolutely did not expect him to call me out. I was just teasing Andy because he and I were just discussing this in another long comment thread like the night before this video aired. I in no way actually expected to be mentioned. If anything it just surprised me that he called out any one person when I saw several people tell him the same thing.
"If you want to provide better information than he is"
Again: Huh? I'm agreeing with Andy's own comments that 3.2v is too low and providing literal real world examples that I have actually seen first hand, as evidence to why 3.2v is too low to balance. Several other people who are experienced with LFP cells have jumped in in other comments to say the same.
"perhaps it's worth starting a channel of your own, anyone can do it now"
Ask Andy how many hours he invests into this every week. This is not something that just "anyone" has the time and energy to do. Taking the time to set up the cameras to get the correct angles and setting up screen readers and then going back and editing in the various shots from various camerasa and screen captures with the video. That's a LOT of work. I don't think it's fair to imply that this is so easy "anyone" can do it, because there's a reason that not everyone does. I have a lot of respect for the amount of effort Andy puts into this and there's no way I would have the time to put this kind of footage together. I have a full time job plus an infant and toddler at home which is another full time job in and of itself. I already find it hard to find the time just to *work* on my battery projects. Taking the extra time to film it all and edit all the footage, upload it to youtube and respond to people's comments? No way. I love that Andy's doing this and only hope that he finds my comments helpful since I've already done most of the testing he's done building my own packs.
I have a fun challenge for you. Cycle a pack with balancing disabled, cycle a few hundred times, then do a capacity test to see the difference. If any.
I've cycled packs without bms (bottom balanced obviously) for months and the cell drift was minimal. I would balance every six months. Not telling anyone to do this though. But balancing isn't that big of a deal. My friend builds 1000Ah+ packs with Orion BMS and the passive dissipative balancer does the job. Very minimal balance current too.
That's why I never care about balancing really. It's rarely used. On a high quality cell pack, with low c rates, and matched cells, those packs won't balance for the first year or so. The balancing circuit will be triggered at high soc, as always due to the nature of the soc curve for lifepo4, but it won't really balance them because it will constantly bleed off highest voltage cell, which will vary by the minute. So balancing isn't doing a thing.
I did this with grade b cells too. Ir was all over the place and so was the capacity. One cell was 10% less than the others! But I just bottom balanced, set absorption, then cycled. No issues at all.
This will take a long time to do.... and besides its good to balance your cells, mostly to prevent voltage sag underload and having your inverter reach its low voltage cut off. I've noticed that its when the pack is at 15 to 80 percent state of charge that all the cells are around the same voltage how ever its the amp hours that each individual cell has inside of it that will make the difference when underload. That's when you see some cells hit their minimum voltage... if just one of them is "bad" then due to the charge curve it will bring the pack voltage way down... Having said that, I do agree with you 100 percent you can hold a pack in balance for 6 months easily... but but why not put the best bms on your battery pack?
i found that if the battery is not pulling and charging with excessive of energy the cell drift will be minimal. i charge the battery with constant 100a and the discharge is 100a ~ 200a, i can see the voltage different less than 30 cycle.
@@wenhaowong5549 whats the total amp hour of the battery pack? Also the charge/discharge rates in relationship to the total capacity of a battery is called its "C" rating. The lower the ratio this is the lower the charging/discharging "C" rate you will have which is what you want.
@@raymondcasso7966 yes, i know that, my battery bank are 202ah, so charging c rate was 0.5c, i have try to increase the battery bank to 404ah so the charging rate is just 0.25c, however the cell drift is still noticeable.
Hahaha... You absolute legend Andy!
I love it when people prove me wrong by doing proper testing like this, because I learn something. My assumptions were just that, assumptions based on the info I had at the time, and the end result (as you found out) looks the same from a user perspective for putting a load on the highest cell, or putting a load on the highest cells. It's an interesting way of balancing, and it's certainly not the most efficient, but I'm sure Daly has its reasons. I do think the JK BMS that takes from the highest, and puts it into the lowest, is a much more effective system. Hopefully Daly is working to keep up with the competition, because I think they may be lagging behind lately.
You are correct, there are better BMS's available for different setups. The Daly was chosen due to its 250A rating (for my batteries) so a 12v battery can run a 3000w Inverter at full load). If I used one of the other brands, they max out at about 200A generally, which wouldn't be enough. I'd love to find a good 250A 4S BMS, does anyone know of one? I also chose the Daly BMS because I wanted my batteries entirely supplied by Australian companies, so I went to Solar4RV's in Victoria for the BMS's.
For people who are using, or consider using the Daly BMS, they are good providing you have good cells and they are well matched. So do the build properly and top balance them to start with, then they will give you plenty of good service. If you're using particularly dodgy unmatched cells, or second hand ones, then you might be better to limit the maximum output current and use a BMS that will provide higher balance currents. T
Thanks again for an excellently produced educational video! I got a lot of laughs from the video too.
Thanks a lot, Paul. Without your initial comment and thought around that, we wouldn't have 'cracked the secret' 😂. Team effort 🤝
So your balance start voltage of 3.2V makes actually sense in combination with well matched cells. Hence you test them all individually before putting them together in your packs.
I just tested the balancing function on eve 280ah cells built into a 48v pack. My cells were factory OOB. The cells came to me around 50% and the first charge was crazy unbalanced (0.312v). However, I brought them down to 75% SOC and changed my Balanced Open Start Volt to 2.7 and Balanced open diff volt to .02. After just two cycles of 100% to 75%, these cells are pulling full capacity. No top balance required. Great Video!!!!
so now that they are balanced, did you change the balance settings?. what did you change it to?
Andy I have a 120A Blue tooth BMS that ballances the same way (Not Daly) - It balances 60mA but on 320ah cells it would take ages from newly assembled despite initial parrallel charging - To get round it I used my little T8 charger to do the initial charge - it balances as it charges up to 15watts - I disconected the BMS ballance leads as I charge so the two ballancing regimes did'nt conflict - The Battery was balanced perfectly with each cell 3.6V - I then disconected the balance leads and charge leads from the T8 then reconected the BMS balance leads and the battery has stayed in balance this past 6 month despite heavy use ( Her hairdryer). I concluded that my BMS can keep matched large cells ballanced in regular use but is too feeble to balance a freshly made up pack on its initial charge.
Thanks for sharing Trev. The initial top balancing is indeed important and the BMS has only little work to day afterwards. Hence these balance current of just a few mA could be enough to keep your pack balanced.
@@OffGridGarageAustralia It's ironic that a little charger designed to fast charge RC "toys" in the field has the kind of features that are so lacking on most mains chargers - To be able to activly balance as you charge - set charge currents and terminal voltage and warn of any critical malfunction automaticly shutting down - max 30amp charge continuous charge is good too.
You should get an active balancer, look at the Heltec units. Passive balance is so slow it’s pretty useless on large battery packs. With active balance you pull power out of high cells and push it back into low cells at the rate of several amps. It’s way faster than draining high cells to make heat.
Thanks for taking the time to do the video. I was going back and forth with you about how my dumb Daly has been working flawlessly. I rarely see more than 5mv difference between cells. Oh I'm surprised you ended the video talking about using larger cells because I'm using 8 280ah cells and couldn't be happier with how perfect they stay balanced and protected.
My personal experience for the last 6 months have shown that even a small passive balance it works flawless. I can almost guarantee if you take the time to put the daly on you 280ah cells you'll see it works just as good as any other BMS.
That is great, Riley. Thanks for sharing. I think this reassures people that Daly BMS are actually working. What is the start voltage for your balancing?
If cells are matched then a small balance current is enough. Not sure what happens when you have 3 ones that are not like the other 16. I think Andy 1st pack have something like this
Hi Andy, I don't know why there was a confusion in the first place. Isn't passive balancing always bleeding off the higher voltage cells? Otherwise it will not make sense right. I dunno how your QUCC balancing works but I thought passive balancing has been always like that.
You will see in the next video...
I have shown the QUC in this video
Hello from the high desert of New Mexico USA 🇺🇸. Hey Andy congrats on another great video, you really have become the G.O.A.T of solar power on UA-cam. Keep up the good work and stay safe and charged
Thanks very much James. The GOAT 🐐
I have torn a Daly BMS down for repair and found it just uses the standard cheap common balancing and monitoring IC SH367309, I posted the english datasheet on the diy solar forum. This will give you every bit of technical information you could ever want on how DALY does balancing. Based on the circuit and the chip in use, I don't see how it could do something so dumb. I am still in the process of reverse engineering the firmware and once I get mine working (waiting on parts) I will capture how it's configuring the chip.
Edit: I can confirm that DALY are using the reference circuit in the SH367309 datasheet for balancing, except DALY are using 131 ohm resistors, which equates to the 25mA balance limit. The transistor feeding this resistor is a S8050 (NPN Transistor) and is capable of up to 500mA, in theory these resistors could be altered to increase the balance current to around 300-400mA without overloading the transistor. 10 ohm should be good for this, and a common value, you just need to ensure the resistor is rated to dissipate the heat.
Thank you for these information.
Paul is indeed correct. When you measured the current on the cell 2 the current is negative. So you are not measuring de discharge on cell 2, you are measuring the current going to cell 3 (to the negative terminal). So your conclusion about balancing all the cells is not correct. And you didn't measure cell 1 to triple check your conclusion. And you could try the 0-3.0000A meter from ebay. That one will have enough resolution with its 5 digits.
Yes, you're absolutely correct, Jonathan. It'll be in the next video.
Once I realized how DALY passive balancing works only when charging AND my bank got out of balance (I had to top balance), I bought the DALY 1amp smart active balancer. It seems to work very well and puts the milliamp discharging algorithm to shame since it moves charge around the cells.
Create a problem... then fix it. Brilliant! 👍😁
I really needed to know how it works and show everyone so they can make their decision which way to go.
@@OffGridGarageAustralia Love love love your channel and content. 👍❤️
Hey Andy, on those cheap amp meters you can actually calibrate them with the small potentiometer on the back. One for voltage and one for the current
I saw these potentiometers but they didn't do anything when I twisted them. I'll have a closer look, I quickly tried only one without success. Thanks for you tip and confirmation.
@@OffGridGarageAustralia They are real fragile, but should make them more sensitive.
You did it, Andy! (But you have another opportunity to impress me….read on). Outstanding job uncovering the mystery of exactly how the Daly BMS (and QUCC) works! I totally understand your situation regarding the 280ah cells and the demanding loads you put them through. But I’ve read on some Daly spec sheets that the larger BMS’ (200ah and above) use a 200 +/-50 mah balance current. Worth independently investigating and then…time for another test and video!!
Thank you Ed. I've seen these other BMS from Daly with higher balance current. I wonder why they have increased it if so many people said 30mA is enough 🤔
I think the Daly BMS's with the fans have the higher balance current. There's such a lack of real data and information on these, it's a big downfall in my opinion.
I can confirm that my Daly 200A BMS uses ~200mA balance current on all cells, ONLY while charging, and ONLY when the voltage is above the setpoint.
You have cleared up SUCH a huge mystery for me. I am still using Lithium Ternary ( Li-Ion/Cobalt ) chemistry, so I have my BMS setup to charge between 3.10 -> 4.2V and begin top balancing the charge above 3.7v since the daly ONLY BALANCES WHEN CHARGING.
Man, that's such a game changer for the way I have been treating my battery stack. Knowing it only cuts in during charging means I only have a slight loss of charge current, and only if the cells are outside of the 50mV margin I set. Now my battery regularly stays within 5-7mV top balance!
24:38 This is how the DALY BMS is working.
Thanks!
I have been using the Daly bms for over a year on two 48 volt banks of 280ah cells and they work perfectly, the balancing is slow but over time the difference is within a few milliamps. Now if I could only find a way to trigger a relay at a given soc, I would like to dump excess capacity to an electric water tank.
I was reading thru some comments and saw where you wanted to dump extra power. I'm doing just that. I use a adjustable voltage sensing relay and a solid state relay both bought from Amazon. They were not expensive at all. The voltage sensing relay doesn't carry much amps so it wouldn't work by itself but it triggers the solid state relay which carries plenty of amps. The solid state relay then turns on my heating element in my electric water heater. The voltage sensing relay is very easy to set up and works great.
after having watched one of your previous vids, and having bought a Daly 14s 120A, i was beginning to have my doubts... all good now. cheers
The Daly does its job. If your cells get out of balance at the top charge, just get one of these little active balancers as well to help it out there.
@@OffGridGarageAustralia considering it's for a Li-Ion pack that will be quite heavily used in an off road vehicle, i'll have to see what it gives once i complete the build. thanks for the vids!
You should look at JK BMS, they offer active (capacitive) balancing. Daly requires an additional module to do that.
Daly, they balance all cells with high voltage because its the most energy efficient. It will make sure the lowest cell (that dose not get balanced) will get in range as fast as possible of the other cells and I guess even that the balanced cells are even helping the charge source to flow energy into the lowest cell that is not in the balance chain . Its a great design I say.
Thanks for your video..
Thank you. I guess their technique comes from Li-ion batteries where voltage is linear to the SOC. This method does not work with LiFePO4 though as once the voltage is rising, the cells are already full and charging stops soon. So does the balancing then.
Have you ever wondered if all of us DIYers are the test beds for the companies that sell micro wind/PV? There are a few manuals out there that cover certain aspects of micro wind/PV, but very few and most are not that detailed, nor do they cover all aspects. I have found my old Schaums classroom supplement extremely helpful on a number of questions, but if not for the likes of you Andy, Will Prowse, David Poz, etc. many of us would be lost. I did finally buy two Daly BMS, one for the 48-volt pack and one for12v testing and pre-assembly balancing based on this review. I have to admit, I did really want to get an Over Kill system or the one you have but getting electronics in the US is a hit and miss proposition these days with all of the tariffs and transportation problems. I actually found a US company that sold Daly and had them in stock, so I got my order in 3 or 4 days instead of 3 or 4 months from China.
Thanks
Make What great again, 👍 you are What greatness is made of.
Wow, thank you 😉
The trick to making a Daly Smart BMS balance properly is to use the Sinowealth software on a PC to set the minimum charging current for balancing to a negative value. That way it will continue to balance while the charger is floating at full charge. It's a real shame that this setting is not available in the APP.
My Ozzy brother I'm in Qld hot as hell up here everyday man and I'm trying to learn as much as possible from all the guys in Australia and USA and global what they are discovering about solar and I'm learning from all your mistakes which will save me money and having to walk path's Of frustration a chap in USA is testing Daly BMS Only to find that he is having balance issues too. And I'm talking about s7 Pak taking hours to balance and imagine how long it takes to balance Big Battery packs Hey maybe we need look@ better than Daly
For what it's worth.... If your current signal is only 0.2 Amps, you could loop the wire through the sensor 10 times and the signal would be 10X stronger and would appear as 2.0 Amps
Yes, that is correct.
Wusste gar nicht das Du aus Deutschland kommst. :) Das erklärt aber warum ich Dein Englisch so gut verstehe. ;) Habe mich schon immer gewundert. ^^
Thanks Andy - great stuff! 👍
This one gets a F for Fudged! Classic I love your vids Andy keep it up.
Don't say that out loud! 🤫
Just bought 3 off ali express. Have a 24v one. Great. It takes a long time to charge a battery bank and that gives a chance to balance. Top balanced so they don't need high amps to balance. Just small amps to top off.
Absolutely, if you do your initial top balance correctly, they will just work. I personally still don't like this method though as there are better ways of doing it these days. But that's just me 😉
@@OffGridGarageAustralia sure, but charge transfer between cells requires a matrix of capacitors, which will all eventually fail. I like long-lived resistance based balancing the way this works... it's simplicity is also longevity.
Thanks Andy, I just got a Daly BMS before I saw this (the first time I watched it), and so have since ordered a JK, I think you wrecked my Daly & I haven’t even got it out of its package yet. As soon as I saw you bring out those Chinese ah meters I knew you were in for trouble, I have used them a fair bit for different projects & know they can be very inaccurate to say the least as you found out, but my projects weren’t as critical as yours for this purpose. If ur going to any 4 meters for this type experiment you must check each one for accuracy, especially when measuring such small currents, shame on you Andy! You know this. Anyhow, thanks for another great vid & info, Cheers
If the charge current is removed due to high cell voltage the cell balancers still stay on until they drop below the cell balance set point?
By the way it would help in clarity when absorption term is met by the term density of energy in a given space. The cells are quite different in size and density is a measure used. So when it comes to absorption it is an increase in density and you can sit at above 3.4 V and push density for a very long time. the so called capacity of a cell is i guess based on Nominal 3.2v and the highest possible density without a Voltage raise. So you put a constant voltage as the limit and keep pushing the Amp in and see them decline to zero. And that is probably what they than call 230ah or 280ah capacity, but if you take the cells to a higher voltage for example 3.39 V and do the same you should show a different total capacity or better have , because you have to consume the energy to make that visible. I do not have time for that. I just know we can run more hours from 6 pm to the morning on the battery set and there is more V left in the morning. So my recharge back to 3.2V where the hard part of re-charging starts goes faster and I want to be there before the best power comes in as the sun rises up. The Deye inverter has the MPPT and their default programming is excellent. My mistakes were to misunderstand the BMS and how he obtains SOC . He doesnt, contrary to the Deye inverter who looks at absorption the BMS does not. I overlooked that the BMS is relying on my input to tell him what SOC he is at. And i thought by putting in the size of the Bank 460 Ah 2x16 that he is the one doing it just like the Deye. Bummer..The Deye monitors resistance and auto holds at 57.60 and than reduces the current to hold 57.60 . so he effectively reduces the panels current coming in. I assume it is the panel input he is reducing but I am not sure where he puts the excess energy . when you see the current is declined at 57.6 V you know you can run more appliances as their is hidden energy ..the battery pack will only handle lets say 1 KW at 57.6 V but you have theorrethically based on day time by experience as you can not see it displayed , 7 kw coming in and the house using 4 KW so there are 2 KW the Deye makes disappear as he reduces the current going into the battery as the resistance against charging grows in the Battery. The absorption in another word. the higher the absorption at fix V the more the current will decline .And the differential is still in existence if you just hook up other appliances . start another aircon so to say. Instead of running 2 run 3 . And the same is true in reverse to give the battery priority in absorption , you turn of an aircon until the current is coming down to below 2 kw .
Why did cell 3 show positive 25mA balance current while cell 2 shows negative 25mA balance current?
Because Paul may be still correct and it balances only the highest cell, not all. I didn't pay attention to pos or neg 🤦
Hi Andy, I wanted to leave the conclusions up to you, but that's exactly what I've been thinking about.
You are my favorite youtube channel!
Thank you for this great video. Nice to see how you figure out the issue, step by step and show it to us. But 30mA of balancing current is a way to low, much much to low. Greetings from Germany
Greetings from Germany, too. All daly bms above 200A will Balance with 200mA
it seems to be working like all the cheap bms i have scene they dump the excess voltage into resisters to bring the high ones down and hoping on a wing and a prayer that the lowest one catches up before the cut off voltage is reached and when you get to large banks it will do nothing at all
I have not got any 4v light blbs so I use Peltier plates instead
That was a 12V car light bulb, Alan.
Yep, good confirmation! Some have said that is the reason they prefer the active balancing vs those daly's etc. The daly burns power and the active balancers transfer power... Oh, man I need to send you a good old USA made spat of bush light! hahaha..
Hahaha, thanks Dan. I had so much fun during making this video, couldn't help myself when I got closer and closer to actually find out and show how it is working 😂
I definitely prefer the active balancing of other BMS' as this is the way to go these days. Passive balancing seems a bit cheap and outdated.
hey Andy " no more Daly on da barbie q"ah lololll 😎😎😎😎 DALY DALY DALY .WE LOVE U DALLY .😂😂😂😂😂😂
Oha, wait for the next video then...
If you want Daly BMS start balance there are three conditions for Smart BMS balance opening：1. Charging status 2. Reach the balance opening voltage: LFP Max 3.2V, Li-ion Max 3.8V, LTO Max 2.4V(Upper computer can set) 3. Battery voltage difference more than 50mV(Defaults value, upper computer can set)
You would balance your battery packs before you even fit the daly BMS
The BMS is designed to keep the cells in balance over the many charge & discharges over time with use.
Yes, that is absolutely correct. The initial top balance will equalize all cells first and the BMS balances little variations during usage.
Those meters look like AliExpress specials 🤣🤣
It needs to pulse the balance current in order to measure the voltage thru the same leads as accurately as possible. Some balancers may be faster or slower (as are some meters).
So 2 sets of wires would be better :)
It does not measure the voltage accurately anyway as the balancer only works while charging.
I have a 4s battery made from poor quality cells and one made from good cells. The poor cells have a large delta at the bottom of the curve and a smaller but non-trivial delta at the top of the curve but the two cells that are the highest at the top are also the lowest at the bottom. That means that somewhere in the middle of charging they cross paths and the lowest voltage cells become the highest voltage cells. If I were to allow balancing to occur anywhere in the middle of the charge curve, I could easily be reducing charge current to the cells that in the end will be the lower voltage cells. In other words, I will rob from cells 3&4 half way through charging and then rob from 1&2 near the end of charging and because I was robbing from 3&4 earlier I will damage the balancing for the pack.
The battery with the better cells does the same kind of thing but with much smaller deltas and with no balancing at all it is in the 3-4 mv range at the top of the charge curve. I am making this comment at 3:50 into your video so now I will see if this is the same conclusion you come to later in the video. Really enjoy your testing videos.
SPAT is definitely where it's at. That's coming from a guy who knows what he's talking about. Texas born and raised!
The reason why you would put balancing lower is if you have a cell which has significantly lower capacity which means it’s voltage will increase faster.
Operating Current:
Thanks Andy
I have my daly bms connected via Bluetooth to a raspberry pi and use python to query the bms every 2 seconds I can confirm the daly bms discharges 2 cells arr a time that are more than 0.002 than the lowest. Also with 200a or higher bms it’s 300ma not the 30ma
Hi can you help, Is that over 200a discharge or charge current? where did you find this info?
I have a 250A smart one (still in its box), but it has 250a discharge 125a charge current printed on the front of it. I can only find the data sheet showing 30ma.
@@garys-half-baked-offgrid-dream in my spec sheet it don’t state any size it but on there web site it’s hidden away in one of the spec sheets that lists all of them in a table I tested my one and seems to balance at 158ma but my pack is fairly well balanced.
@@robben8704 Cheers Rob I will chexk it out.
Thanks for sharing, Rob. Wow, great project with the Raspi and Daly.
I did another test with the Daly and found... well, it's in the next video.
@@garys-half-baked-offgrid-dream The Versions of Daly BMS with the fan are the ones with higher balance current as far as I know.
In my humble opinion these test results are a good indication of what is happening, but are not totally accurate. By putting the multimeter in series with the battery lead to measure the balance current, you introduce the meter's burden voltage drop on this lead, so when the BMS starts discharging this cell to balance it, it reads a lower voltage than the battery actually has, scewing the results a bit and causing the BMS to stop the balancing action, thinking that the cell has dropped in voltage. This becomes more evident when using the mA ranges of the multimeter due to the bigger internal shunt resistance it uses. These kind of measurements are more difficult than they seem if you want to be completely accurate! Nevertheless, really nice and educational video!
Thank you. The test shows the principle how the BMS works, a few mA less or more does not matter for that. I don't know how large the shunt inside the multimeter is and what voltage drop that would cause.
If those meters can’t even read the voltage accurately why trust them to read current ? lif3 cells at 4volts, clearly they don’t work well even to use.
The numbers don't matter. It was more to show current is flowing or no current is flowing.
Andy, not to be a nit-picker, but that work bench would drive me crazy. Those gaps between the boards make me think there are lots of little parts on the floor somewhere. You got all that nice aluminum sheeting you used on the cabinet for the batteries. Either that or some plywood might make the work bench a better spot to use small parts. Just sayin'
Ya when you were saying at 3.2 it is doing all of them didn't make sense to me ya because just because it can balance if they are all the same voltage it shouldn't balance anything regardless of voltage
My recent researches (recent video on my chan) show that Daly smart BMS 4S/100A which uses Sino Wealth SH367303 frontend IC, balances/discharges only single cell at a time, the one which has highest voltage.
If another cell appears to have higher voltage, the IC will jump to balance/discharge it and leave previous one.
PWM is 70% or 45% (on 2 a little different examples), final balance current is ~33mA as declared by Daly!
Also, important detail - DALY will not start to balance after its restart until it will see a change current for a few seconds !!!
Yeah, Daly is still not great. The balancer function and efficiency/effectiveness is their weak point.
Remember 10c recycling for each can
Absolutely. That's all the cans from 3 months, so getting 60c refund now 😂
Heya, those daily bms are working good but for your purpuse they will not do so good as you need higher amps to balance your battery pack
Great video. Thanks for all that great information.
Passive balance function is so simple, the balance part only adds a parallel resistance to the battery cell with the highest resistance.
Since some cells have lower resistance, those with the highest resistance will be charged first
This moment when the SmartBMS is smarter than you thought and it takes a while to find out...
....and then at the end of the video you punch it in the face and point out that it can only punch back with 23mAmps against your 14.4kW battery.
Hahaha, yeah outsmarted by the BMS 😂😂😂
🤣🤣🤣 really enjoy ,your vlogs ,Thanks Andy! 🍻S.P.A.T 🍻
Thanks 👍
I think these bms's only good for over current protection. Balancing is useless. Imagine in a real time scenario when you are pulling constantly 30-40 amp and the same time you are using 30-40. How will 30ma balance the batteries?
Hi nice test indeed. I have a question, what is the real effect of 30ma balancing while charging at10A+ ? I'm about confused about this even if my 16S 200ah Lifepo4 get balanced within 10mv every day. what's the phisic that I'm missing here . Thanks
Off-Grid test setup = Nest of Snakes.
Next Question: once the lowest cell charges to match the 2nd lowest cell, does the Daly stop balancing 2nd cell and begin to charge them both? They are now both lowest voltage in the pack.
Does it continue this process? as cells are brought up to match the next highest voltage, does it stop balancing that next-highest cell? (thanks for figuring this out!)
It does that, if they are within the minimum 20mV deviation. No balancing if cells are withing this range.
Or put it the other way around, it will always balance all cells but the lowest if:
- the set start voltage of the balancer has been reached
AND
- the deviation is larger than your set voltage delta (20mV seems to be the lowest)
AND
- the app shows a charging current (needs to be around 1A or above)
@17:20 - 17:25 the balancer was of in the app but was discharging @ 23ma
This one gets an "F" for "Fckd" :D Love it!
Don't say it! 😂
I think balancing is secondary to protection/safety. One question is - do these BMSs do their job under fault conditions? For instance, if the inverter/charger is charging and either max cell voltage or max total voltage is reached, does it disconnect, or set SOC to 100% in the process, etc? Same with max temperature settings - do the BMSs do their job? I find these systems (BMSs) full of bugs (therefore dangerous), and very dependant on firmware release function. They tend to mend one thing and break other safety features with each release. Everyone ignores safety - more interested in having a nice bluetooth connection to a pretty phone GUI!
All the BMS I have ever tested had the basic safety functions: voltage, current, temperature...
@@OffGridGarageAustralia I had Deye interfaced to Daly on CANbus. It allowed charging despite both max cell voltage and sum voltage being reached. It could also be related to Deye - Daly did raise alarms - but in my mind Daly should take further control - at least raise SOC to 100%, and probably disconnect itself and all parallel Daly BMSs. It certainly did not do that. Thanks for taking the time for the videos BTW.
I would still prefer JBD as they have been more reliable and easy to get functioning for more people. Daly have a few bugs which i don't trust for reliability especially if you are very dependant on your power like mobile living and do not have the tools/gear to problem solve and fix issues on the go. Also a few model JBD BMS i have are 150mah balance current and they do 2 cells at a time. Active balancing is coming out in some BMS like Heltec and i think i saw a JBD BMS the other day with active balance too.
Well back to these Daly bms again I have two one is a 40a the other is a 30a that means I'm supposed to have at least 70 amps of charging but one of then keep shutting everything down once I hit 50 amps everything cuts off I don't understand why..
What batteries are they connected to?
If you have two batteries in parallel and each has one of the BMS connected to it, the overall charging current will split in half so 35A will go in each of the batteries. That would be too much for the 30A BMS and it shuts off.
You can only charge with 60A max.
@@OffGridGarageAustralia each bms is connected to a 24v lithium 120ah 8 cell bank
I love the work you put into this. I do have a question? how to configure the DALY 250A bms to charge the cells to 3.6V?? I have one and it stops charging when a cell hits 3.6v..but the rest are below this. maybe 3.4...3.5.. the balance is set to 3.2. should I just wait..but charge current is 2ish amps for 200ah cells..( I'm skeptical they are really 200ah cells). thoughts?
The bms just measure ea battery then when it find the diference voltage and the starting voltage you progranm just start to modulate the input of all bateries in order to give the oportunity to spread the voltage to each battery. just use the cables to meassure.
Kierunek połączenie amperomierza też ma znaczenie daly bms obciąża rezystorem cele z najwyższym napięciem i zrównuje je do celi z najniższym napięciem pozdro
So is the final conclusion to set the Balance open start voltage to 3.2v on Daly bms??
I have used those volt/amp meters and if I remember correctly the current measurement is expected to be in the negative lead and this should be the negative of the supply to the meter.
Ha ha 30 seconds further into the vid you found that out.
I use a daly for a 24v setup.i set the (diff volt shows .05) I set mine to .03mv.it will start balance when cells reach a 30mv differance
thank you!
Echt geiles Video. Das beste war in deutsch.
Wollte mal sehen wie viele bis zum Schluss gucken. Top👍
Hi, do you know how to explain a page in BMS „collect board settings“?
Moin, Australien hat so leckeres Bier, wieso dieses süffige Studentenbier? Weiter so, macht Spaß so seinen Horizonzt zu erweitern.
I can't turn on the balancing. am i missing something ? I can't set the nr off strings or change the balancing current.
You still need to start above 3.4 - but my balancing only adjusts the highest voltage - and doesn't pull down to a voltage, its balances to a delta.
Maybe just your QUCC was using weird balancing and made you think they all are as bad as that one?
Anyway ... now to watch the actual testing you did, see if you have sorted that in your head now with the testing :)
And I'm having a issue with my Daly Bluetooth BMS 40a/80a it keeps cutting off the system at 53-54 amps of power draw when it's supposed to allow up to 80 amps of discharge I don't understand why I can't get no more than 53-54 amps
Which BMS should I get? I'm trying to be as cheap as possible... but work. 14S, 5P- 4000mah LiPo. I never want to charge the cells past 4V.
Thanks "Andy the Great", that was a excellent video, I will look at lowering my balancing voltage start to 3.2v, the smell of smoke in the air this nothing new when experimenting with voltages
Glad it helped, Ross and you left a thumbs up this time 😉
Nothing better than this smell of hot electronics while testing 😂
Hello. Does it work for you? I got 2 S8 100A and they don't work. The crooks at bankgood didn't send me the bt cables to pass the time, so I can't claim my money back. The shipping time was over 30 days. The cost of return is more than 1/2 of the purchase.
Can you turn it on if you have not been sent the round plug in thing??
Really!!?? You both were wrong I tried to tell you three videos ago you wouldn’t listen. You don’t charge your 280 amp hour batteries with one amp! Oh my God Andy go online it’ll explain it all to you
Paul was indeed right!
I’m new to all this stuff but that is how I thought balancing worked in general, once a cell goes higher than the diff or delta that you set it balances that cell.., that’s the only logical way any balancing works in my mind or vice versa I guess if anything balanced at the low end but I don’t know haha
Yeah, nah. the Daly works quite differently. Watch the next video...
Yep I watched now I know haha thanks for all your hard work and testing. I would need the days to be 50 hours long if I was ever going to do as much testing as you do.
When you measured the current on cell 2 wasn’t it showing negative current? Wouldn’t that make sense.
I saw that too. I think he just had the polarity backwards since the Daly cant push current into the cells.
Yes, that was my mistake. Rectified in the next video 😊
@@OffGridGarageAustralia 'rectified' I like what you did there.
is it OK for me to bleed the higher voltage of my battery i just ordered 32pcs sinopoly and i don't have the money to buy bench charger so I'm thinking of bleeding the higher voltage of tht batteries
Yes, that will work as well.
@@OffGridGarageAustralia thank you very much my teacher I'm one of bigger fan
My Daly 60a bms just stopped working I believe it's only detecting 2 out of my 8 cells it was just working fine I thought
Exactly, I mean what 30ma is going to do when you build a 280A battery out of 4s? makes no sense. so the question is, should I get one of those 1.2A balancer if I want to build a 280A 4s 12v?
If you have a Daly, I would get a balancer, yes. But only balance at the top of the charging curve!
@@OffGridGarageAustralia What about JBD? same story?
I've seen batteries from china with JBD without an external balancer.
@@mhnoni yeah, same low balance currents for the JBD BMS. Hence I went with the QUCC BMS, it has at least 200mA of balance current.
@@OffGridGarageAustralia Cool, thanks a lot! :)
Hi Andy, yes but the 16S daly probably uses higher currents
Nope. Just the higher amperage BMS's ( 150A+ ) and those still limit balance current per cell to about 200mA ( +/- 50mA )
Hello..
I have watched several of your youtube videos, and I have seen them all to the end....
I'm now wondering if you can answer me a question... I bought a 150A Daly smart bms .... after installation etc. it turns out that the bms didn't read load below/over about 2.5A .. So I would be grateful if you had an answer that helped me get the bms to read low load.... as I have searched with lights and lucked out for one....
Many thanks in advance
Peter N from Sweden
Hi Sir, i boughr a new battery bank ant bms , i cant charge, wont turn on, ir seems like its its overvoltage protect mode,
I set my Daly bms Balance Open Start Voltage to 3.45v is that correct because no one has actually said what voltage to set it at 😞
I am not sure if your up to this ANDY, but..... idea.. frankenDaly modding... maybe take the daly apart and see if we could figure out the circuits for the bleed resistor circuits, because the cables and pads should be able to support higher bleeding... so.... maybe mount the daly to a larger aluminum sheet of metal for heat sink and upgrade the balance bleed potential... idk.. just an idea.. almost sounds so simple, that you could easily build a DIY version completely with an arduino or something... just have a simple code that checks the cell voltages every 1 second, then based on boulian code... balances all but the lowest...
Dude, your videos are awesome! Sehr geil!
I'm not sad now!
OK, wait for the next video 🤔
So you will set up a live call with Will Proust and compare your notes on Daly?
Having a 'Beer 'n Beans' talk!