Something wrong in the battery shelf! Or just 'bad' settings?
HTML-код
- Опубликовано: 11 сен 2024
- Since we have installed the battery shelf, the bottom battery showed a deviation when fully charged. I wasn't quite sure why that is because we top balanced all three banks at the beginning and the top and middle battery were perfectly fine.
For testing purposes, I have already swapped the BMSes in the top and bottom shelf battery. The problem seems to stick with the HELTEC BMS. It is causing this weird imbalance between the first 10 cells and the rest of the cells in the pack. Now, after 6 months, I can observe the exact same imbalance on the top battery where the HELTEC BMS has been installed. So, what's going on?
Talking about balancing: Some (3) viewers told me, that I'm charging my batteries wrong and 3.45V would not be enough, to fully maintain the battery including balancing. So, here we go, I'm doing the test and change my charger settings to the following:
- Absorption 56.8V
- Float 55.2V
In a few days, I want to increase the voltage to 57,6V which is 3.6V/cell. I want to observe if the passive balancers are actually work and are able to balance out all packs.
Maybe this is the way to go and the other batteries and BMS will actually work if charged to a higher voltage? Leave your thoughts below...
12% discount on the Gobelpower Battery for a limited time!
off-grid-garag...
8% off all Jakiper batteries in September:
off-grid-garag...
Charging LiFePo4 (LFP) to 3.4V and 3.5V with and without Absorption. What a difference! • Charging LiFePo4 (LFP)...
Swapping the Overkill-Solar and Heltec BMS in the Battery2.0 Shelf to overcome imbalanced battery. • Swapping the Overkill-...
ZKETech EBC-A40L Battery Tester:
off-grid-garag...
• My favourite battery a...
Please subscribe and join me on my journey of the Off-Grid Garage!
For more information, please check out my website with links to all the batteries, materials, devices and products I have used in my videos: off-grid-garag...
The 'Buy me a Beer🍻'-link is here (on the website, scroll all the way down):
off-grid-garag... Thank you for your support!
You can also click on the Thanks button under the video to support the channel. Thank you, if you have already!
T-Shirts, caps, mugs and more in our merch-shop:
off-grid-garag...
**** These are the batteries you are looking for ****
🔋➡EVE LF280/304 LiFePO4 cells 3.2V/280+304Ah: off-grid-garag...
🌞➡Solar charge Controllers, Inverters and accessories: off-grid-garag...
🔧➡Tools, Analysers and Testers: off-grid-garag...
📈➡ Battery Tests and Results: off-grid-garag...
🔌➡Batteries, charger and accessories: off-grid-garag...
⚡➡Cables, Inverters and Electronics: off-grid-garag...
The Sunfunkit DIY battery. Great product to build your own 12V battery. Use OGGA at checkout to get 6% off. More info here: off-grid-garag...
Video review: • The Sun Fun Kit Experi...
Best prices for Victron gear in Australia: Auto Parts Co has you covered.
www.autopartsc...
(they have 4WD parts and accessories too)
Take a live sneak peek at the Off-Grid-Garage in the Victron VRM World (link at top of the page):
off-grid-garag...
Here is my Tesla referral link, if you want to buy any Tesla accessories or even order a vehicle. This is a great way to support my channel. Thanks a lot to everyone who have used it so far 🙏 www.tesla.com/...
My other (German) RUclips channels:
/ offgridgarageaustralia
Please don't leave any links in your reply. RUclips will not publish your comment in this case.
If you decide to send me an email, I really appreciate your time and effort for doing this. However, please consider leaving a comment under my videos instead as I may not be able to reply to your email due to the sheer number of messages I'm receiving.
Soo many battery’s, soo much power 😎
😂
Good questions at 13:40 Andy. In regards to gain in capacity by balancing at 56.3v. After another year and nearly 200 cycles on my 3, 300wh 16s LFE packs, each with a non-programmable DALY passive BMS, and all connected in parallel, with no diode isolation, I found that charging to 54.6v or about 3.40 per cell, which was below the 3.45v the DALY appears to balance at, after about 6 cycles to about 20% SOC, each of the three packs had cells that drifted to as much as 180mv with no passive balancing.
Charging to 55v, was not enough to bring the cells into balance because the DALY BMSs only balanced for a few mins before the cells dropped below 3.45 and the BMSs stopped balancing. Charging to 56v typically balanced the packs to about 80mv in one charge, and 55.6v brought the cells to about 30mv.
Something else I noticed, was that the DALY passive BMSs don't seem to balance as long as a charge voltage is applied as the charging current applied to each cell is greater than the balance current, because the balance circuits simply shunt charging current rather than battery current, and balancing occurs only after after power is disconnected, which in my case makes the case to charge well above 3.45v per cell.
Doing three test runs to BMS cut off voltage, I seemed to gain about 10% capacity at 55.6v over 54.6v. This seems to be due to better cell balance rather than the added charge, but that's mostly observational Watt hours used and some of the gain may be due to temp difference. I need to do a bench test in controlled temp to confirm, but taking the balance from 180mv to 30mv seems likely to account for the range increase.
Does low charge rate degrade performance? Last year on my test packs I was slow-charging between .1C to .2C to 3.40v per cell to try to preserve cell balance and life, and my 3, 300 Watt-hour packs were delivering about 250 watt-hours, this year I've been charging at 0.5C to 1.5C to 56.5v for almost 200 cycles, and the packs now deliver 280 to 310 watt-hours each, and with a noticeable increase in torque and acceleration, that seemed to occur after charging at higher current, so I wonder if LFE cells loose performance or don't fully charge at lower currents?
Finally, I've been charging a 3.2v 1S, 24AH ebike booster pack, that use 4P 32700 LFE cells to 3.75v at .3C, and after 400 cycles the pack is delivering about 8% more capacity than when constructed two years ago, so at this cycle level I'm not seeing any degradation but the pack rarely discharges above 1C and mostly at 0.2C to 0.5C discharge.
Personally, from what I've read and my limited testing, I question if high-discharge rates at elevated temps may degrade LFE cells more than gently charging to higher voltages could result in more cell degradation, some older small-scale Chinese university research testing seems to suggest that, however newer LFP chemistry and materials improvements could have improved that.
Thanks for sharing. Your batteries seem small enough to make the DALY passive balancer work. I could not share the same experience with my larger capacity cells though
@@OffGridGarageAustralia If a passive balancer that that drains about 170ma can barely keep a slightly mismatched 6ah to 24ah pack balanced, I don't see how it could be effective on a 200ah pack.
Thanks for such long term tests! Great to see the JK is doing fine!
The manufactureres of BMSs inverters and so on have also done these tests, they give us a few volts to play with, so playing we do. ;) happy days Andy keep up the good work!
Yes, playing and testing. Could do this all day long... Whoops, I actually do! 😂
I 'm keen on seeing the results after this video, Keep on that way we both love your video's Andy....
Who is 'we both'? 🧐
Must be nice to have so many toys to play with. Your commitment to providing good information on a consistent basis is definitely paying off for you. Thanks.
Thanks for your feedback. I hope it pays off for everyone in the community when I publish these information.
I like so much this video that I'm going to do the same test. Have the same opinion higher voltage will degraded the batteries faster and you will gain 2 or 3% capacity. Probably you will need another 6 months to see significative change :) The BMS from top shelf didn't balance bottom battery so the problem is not in the BMS but in the battery, check everything in cell 7 and measure voltagem when balancing and compare with the value of the bms. Your cells are not compressed so you could swap cell 7 with cell 4, it's the fasted way to find a bad connection or cell. Another great video, congrats.
Just noticed that you changed the float not the absorption so it should balance faster, I replicate it but cells won't like, at the moment I'm doing a daily cycle so results should be diferente but I'm curious.
I followed from the beginning the rule charge to 3,45 volts.
I have an ant bms, with lots of futures.
I do it now for 120 days and my maximum difference is 15 mv when fully charged, i am happy with that, my ant bms do auto charge balancing at 20 mv but never been active at all, i am happy with that because when the charging is finished and 2 hours of consumption, the bms going in rest state and no balancing, when the battery voltage drops to 3,35 there is only 2 or 3 mv difference.
Very good advice from you, thanks
Sounds perfect, thanks for your feedback.
Also I agree that changing and balancing at a higher voltage is better. In fact I had to do this to get my packs working right. And you said your self! At a higher charge, it take less charge to make a bigger difference so when you get it balanced in that high curve, your cells are so much closer together. But I also agree not to start balancing tell 3.45 volts.
But the question is: do you need that balance at a higher voltage? All my three banks are working perfectly fine and I never had a cell peaking even at 3.45V. So why charge higher?
From your previous videos I built a battery pack one year ago (24v system) I have 2 packs of 8, 280Ah EVE cells with JK bms's, 2 amp built in balancing, about 7.5Kw of panels, max and bit more 😮 overpaneled on my 3 charge controllers, supplies about 80% of my electricity needs. These previous settings seem to work really well.
I think one way to truly know what's happening is to monitor each cells daily current flows, which would be difficult to do,
The current in all cells of a bank is the same in a series connection. I just don't understand why the Heltect BMS causes an imbalance on both batteries which were fine before connecting it. And only cell 1-10 in both batteries... strange
Cell ten on the top and bottom rack is the high cell in the video. I think there might be actually something wrong with the heltec BMS. Perhaps a resistor, cap, etc. It is unlikely that the same imbalance would occur twice.
Exactly, that's what I'm after. I was really surprised to find the top battery with the same pattern of cell 1-10 as the bottom battery where the Heltec was before. We may see a bit clearer once the BMS balances correctly at higher voltage.
@@OffGridGarageAustralia OK the presentation has its unique stile, the first one "Will your Li-ion batteries last twice as long if you charge them to 4.1V?" is better and tells rumours can hold tough, even they funded on questionable evidence, just to keep in mind ; )
@@topeye4202It is much more an 'entertaining show' rather than having any scientific credibility.
@@OffGridGarageAustralia Please just take a closer look at the "Calendar Aging Model" which Battery Doctor shows at 1:57 in his Video "Will your Li-ion batteries last twice as long if you charge them to 4.1V?"
The yellow curve is cycled between 75 and 65 % and loses 9% of its capacity within 8500 cyles.
The black curve is cycled between 100 and 25 % and loses 25% of its capacity within 4500 cycles.
First impression: WOW twice as much cycles and three times less degeneration when not fully charged!
BUT
The black curve uses 75% of the capacity 4500 times and the yellow one only 10% 8500 times.
That means the stored energy per cycle is 7,5 times less in the yellow curve compared to the black one.
The loss of capacity is about 3 times less in the yellow one, BUT the total stored energy is 3,97 times less! (8500cycles÷4500cyles = 1,88 7,5÷1,88=3,97)
This means you lose about 25% more capacity with narrow cycling, in terms of total stored energy!
Even though the way Battery Doctor presents his content may take some getting used to, he was the only one who brought it to my attention. The rest of the huge pile that floods me with oh-so-clever entertaining information shows only kept the questionable rumor alive by repeating it like a prayer wheel.
Thats a good example which shows that the first impression were the myths are based on and the result you'll get, after you switch on your brain and have a open ear to non-mainstream people, differs quite a lot ; )
Lithium ion, depending how high of a charge, discharge, temperature can last as long as 2000 cycles+
One important concept that may not have been mentioned in Andy's obsession with balancing is that deltaV is what we use to determine how out of balance a pack is and of course increases as we push the pack voltage up. But it is not a precise indicator of how much current transfer is needed to re-balance the pack, eg a pack with one cell out can a deltaV of 200mV and a pack with 6 cells out of whack can have a deltaV of 200mV. The passive balancers and some active balancers dont reach their full current transfer potiential unless their is a significant deltaV and are very inefficient at low deltaV. This is not the case with Neely and JK Active balancers that seem to transfer at their full capacity once switched on. Love to see a head to head comparison of balancers where pack is top balanced, then one cell is discharged to a set amount and then recovery time recorded to rebalance pack and repeated for each balancer under same conditions. The Neey would be expected to come out on top.???
I don't want to add more to the obsessive testing of balancers here on the channel but passive balancing is not dependent on voltage difference. It is basically just a switch and a resistor and Ohm's law determines the balance current.
The NEEY is great but has one major downside: It can balance only one cell at a time. If several cells are peaking, it struggles and the capacitive balancer is actually the better choice.
Drop your amperage to top balance! I got a cheapie LFP off amazon that had a very basic BMS that couldn't clamp but 20ma on its near worthless balancer. As such I set the current on the power supply down to what it could clamp and several days later it was finally balanced. If your BMS can only clamp 150ma, don't feed it much more than that.
The batterie sits mostly idle when balancing, so no current in or out...
But you're right, if the charge current is larger than the balance current, it won't work.
I like your shop… I have a shop similar… ( not as big) …most if not all of the shops online look as if they were set up to “ look “ like a shop , but they are too neat…… no evidence of what goes on in a real work place. …theirs is all prop and stage looking at best… very little real work goes on in a super clean spotless shop…
Haaaa. And they don’t know it because they have done very little real work in them.
They just talk and talk put on a show and try to sell stuff.
Thanks for what you have done for the solar guys looking for real direction…👍
Thanks for doing the testing Andy. I just purchased a Soluna battery to test, as it is newly UL-listed for use in the US. I see no sense in building my own pack, there are so many available to choose from now that work.
Yeah, the market is large and we have a good choice of batteries.
Hey Andy, I have been charging my batteries to 56.4-56.6v for the last few years mainly because I have noticed the cells will stay in balance. The lower voltage didnt do it for me😀
With an active balancer?
@@OffGridGarageAustraliaNo active balancer. Just the good ole jbd bms.👍
As one of the 3, I apreciate the investigative aproach Andy. You have definitly not used my prcedure or voltage settings in this video, but I am curious to see where this goes. I suspect failure, as an inital active top ballance is required before my passive ballancer settings are used. Side note: I also don't use a Heltech BMS or different types of BMS's in an instalation. I'm not sure if this matters or not, passive balancing is pretty much the same in most of the BMS's.
I have your settings here and will apply them soon. I just cannot charge high enough before 2 of the BMS will go OVP. I have to increase the charge voltage slowly to get there. Passive balancer are working slowly...
But thank you for you input, very interesting to follow you recommendation and test it out.
@@OffGridGarageAustralia all good. I like seeing what other people have recomended too. I am always open to learning. It's one of the reasons I enjoy your chanel, I learn things here.
Like you've already shown though, passive balancing an unbalanced pack would take forever, or posibly never work. It's why I properly top balance a pack activly when it's made and then leave it up to the passive balancing to keep things straight.
I wish you would do a long term test in Winter to have no balancing (passive or active) and just cycle the batteries as normal for 3 months. I think you would be surprised how close the voltages remain both charged & discharged.
Could you poosibly do a part 2 of the power wall 2? Like, ... when did you upgrade the charge controllers? They seem to just show up. Are you using more than one smart shunt? Is the power distributor (Peter) worth it? What advantage is there from using it?
I think I've binge-watched almost every video ... great stuff👍
Great Video! Thanks for this live experiment and process of elimination - greatly appreciated.
Thanks for tour feedback!
When did you change to 3.45 volts per cell for charge voltage? The last I remembered you were saying to start the balancer at 3.45 and charge to 3.55 per cell, mind you, I definitely agree with your theory though. Also, for charging to only 3.45 per cell, would a longer absorbtion time help give the balancers a chance to work? Considering that it keeps the voltage at 3.45 for longer before dropping to a float voltage of around 3.375 per cell. Just a crazy thought that came to mind while watching another great video! Always appreciated!!!
He changed to 3.45v a while ago, logic being that it's at the start of where the vast majority of the power is, so why bother going higher, which is fine.
The problem comes when you then start telling all your subscribers that X and Y BMS's are crap because they don't balance batteries, passive balances don't work and SoC's don't reset unless you drive them into a protection status, when all you had to do was charge 0.1v/cell higher for all that to work.
A while ago... well, 5 days ago to be precise. And just for testing purposes. I will go back to 3.45V after testing.
@@OffGridGarageAustralia I mean, a video on your channel from 8 months ago shows you at 55.2v charge voltage, and 8 months ago is "a while ago" in my book.
Saving your back 😀 nice use of lift it’s on wheels, it has great reach, capacity is more than equal to the job, and getting the lift from the ground up to a working wall height. But it’s making it more of a one man job. Thumbs up 👍
Wish I had one. Getting a SPF12000T on the wall was a pain.
@@chuxxsss engine lifts are not so expensive and there used ones around. Also rentals.
I go from 2.50 to 3.65. With 27 years before they reach 80% of their life, I'll dead before the batteries. LOL
Pretty much, I still like to test though...
Hi Andy, and thank you again for this very interesting video and test!
My opinion is completely opposite, the higher the voltage, the more difficult it will be for the cells to balance.
A simple test allows you to see this, charge the battery, by deactivating the balance system of the BMS, and take a good look at what cell voltage, the imbalance becomes too great. And we can deduce that from this point the limit is reached.
We could try anyway, to force the battery to go to a higher voltage level, automatically the imbalance will increase!
Conclusion, this is my opinion, Andy if you can perfectly balance your cells at 3.45V there is no point in going higher.
Because going to a higher voltage will degrade the balance.
To then go back down to a lower floating voltage???
For me it doesn't make sense, if you want your cells to be perfectly balanced all the time.
The point is that for voltages lower than 3.45V the cell state of charge can not be deduced from a voltage measurement due to the flat discharge curve. So two cells can be at different state of charges (imbalanced) but still have almost the same voltage. It is only at the high and low voltages that the cells reveal their true state of charge. And since the goal is to balance the state of charge it is best done at a high voltage.
"My opinion is completely opposite, the higher the voltage, the more difficult it will be for the cells to balance."
I mean, you're just demonstrably incorrect. Look at the voltage curve of any LiFePo4 cell, and you'll see the current crashes the closer you get to 3.65v. That means with 180ma of current being taken by a balancer, it's easier for it to make a difference when you're only 1Ah away from fully charged at 3.65v, instead of like 5Ah at 3.5v.
You do such beautiful work.
Oh, thank you!
I look forward to the results
If the battery potentially degrades faster, i would not bother trying to top balance it this way. I found an article about it with Tesla LFP cars onlly needing a 100% charge to get an accurate range estimate because of the very flat curve.
The advice in the article is to keeo the SoC between 20% and 70% to maximise it's life.
Maybe for offgrid usage this is much more important, because a home should last longer than a car, and just getting an extra battery and/or extra solar panels is much cheaper and better for the environment than having to replace all batteries within 10 years instead of 30 years. It is also not as inconvenient to have a vague SoC as it is with a car where you need to know in time if you need to find a charger. You are already plugged, and there are way more factors that deviate than the SoC percentage. It might be good to top balance the batteries just every year or so, even if just to plan ahead if more batteries are needed.
I think you are tight here. From further testing I now did, it seems like such a maintenance top balancing is maybe necessary every 2-3 years only. More about this in the next video.
Tesla Model 3 Standard Range uses a LiFePo4 battery pack and their recommendation is to charge to 100% even for daily use. For their NMC packs they say charge only to 80% daily. Maybe that indicates that it is okay to go higher than 3.45V?
Well, that's a bit different. They mainly do this to calibrate their BMS with the system so the estimated km and SOC is correct. They had massive trouble at the beginning with that and then started recommending it.
@@OffGridGarageAustralia Isn't that kind of the same problem you're having? That it is very hard to determine a cells state of charge unless you go to a high voltage by charging to 100%.
I have found through testing that charging to 3.5v/cell or 56v for 16s pack is much better and allows the pack to stay better balanced even with a JK-BMS, balancer start at 3.45v. Much better balancing!
Yes, better balanced but higher degradation?
@@OffGridGarageAustralia There is NO evidence of higher degradation and given the manufacturer says you can charge to 3.6V 6000 cycles (with compression LF280K cells) I think 3.5V/cell is a good compromise.
Weren't you the man that said don't worry about compression calendar ageing will degrade them first?
Same applies here I would suggest.
@@uksa007 yeah, makes sense. Testing different settings right now. Thanks for your suggestion.
@@OffGridGarageAustralia Let me know if you want to test my CAN interface boards for the JK and Overkill/JBD BMS, I sent you an email on 16/8/23 (might help you find it).
Regards
@@uksa007 I'll have a look at your email. Might be in the pool with all the other 1M emails...
It's crazy how it's Spring time there & Fall here in the States
Charge to 3.45 volts and use the JK BMS's on all three packs, seems like the obvious answer, save the other BMS's for backups, for thee zombie apocalypse...Appreciate the testing though, that always confirms my BMS choices...I'll always avoid the steep curves, charging and discharging, unless some unknown information penetrates my reality...Stress degrades and kills everything eventually, whether alive or not..
The middle shelf battery with the JK seems to work best of all three. Even it has aluminium bus bars.
@@OffGridGarageAustralia But still a quite large delta even with a Neeeeeey? Wouldn't that suggest that @3.45v that lower SOC cells once current is applied actually spike up to 3.45v quite quickly and negate the active balancer doing its job? Pushing to 3.55v allows the proper runners to show their real colours and whack a mole can start with the active/passive balancers?
@@AussieAustrian I'll explain this in the next video. I have basically never fully balanced my whole battery shelf after the first initial top balancing. I don't allow enough time for balancing at 3.45V.
Sweetspot for me is 3.55V per cell bulk and 3.45V float. My JK balancer keeps mine within 10ish. My opinion: the balancer needs some volts to do its thing and 3.55V is well under the 3.65V limit one should use. I think you are running too low with your 3.45V bulk charging/balancing but I am not sure if you just do this to create "content"...the tens of years will kill your cells well before any 3.45 vs. 3.55 voltage...but I think you know this already.
You're correct. 3.55v or 56.8v for 16s is what you need to charge to get proper absorption. Anything less significantly lowers my capacity.
There is no gain in capacity if charging to 3.55V instead of 3.45V. The only reason doing this may be better balancing. We will find out.
And no, I don't need to 'create' any artificial content. My list with videos and projects is pretty much full for the next 10 years.
I use your settings on my batts they work well
Amazing ❤
From Indonesian
Hi Andy, it doesn't matter if you load higher, I think the float mode may be responsible. Here in Germany the surplus solar power is fed into the grid, my system never, I repeat never, works in float mode. The Seplos BMS charges my 2 packs up to 55.3 volts and the JK 1 Ah balancer starts at 3.45 V, the cell overvoltage protection is at 3.65 V and the pack overvoltage protection is at 56.2 V. I charge with 120 Ah and I never have more than 30mV difference in both packs when charging with 120 Ah and when the 55.3 volts are reached the difference is 5-10mV in both packs. However, my system never works in float, which means that if the storage is full at 11 am, the 55.3 volts are maintained throughout the afternoon and 1-2 Ah are charged and discharged all the time. I have not been able to find out anything negative about this and many people with different BMSs have this charge/discharge loop in the Victron Community Portal. So for me it is only bulk and absorption and that over 6 hrs/every day.
You basically give your battery enough time to balance, which I never did.
It would be interesting to see what your delta is when you raise the CVL to 57V. Is it still balanced? I would expect it won't...
55.3V is somewhat hiding the true difference and imbalance.
@@OffGridGarageAustralia I will test and tell you, but the next days weather is bad, so give me 1 week
Nice to see that your batteries, once fully charged, actually go into "idle" (standby). In my case (Seplos and Neey) it's oscillating between charging (until 55.2V), then discharging down to the recovery voltage, and back up again to 55.2V. It never goes into idle/standby :/
Intermittent charging stops this and charging is allowed only under 96% soc or what you Set
Intermittent charging does not stop this but only decreases the cycle frequency. It will still cycle the battery between 96% and 100%. Not great.
The Seplos BMS are bad designed in this regards (except the V1 BMS, 10C with FW 2.8 which works perfectly).
Yeah i know what you mean. I also think IT is Not perfect. But i must say it is okay for me. It works and yes some algorythms could be better but hey i think IT is one of the cheapest outside
@@betterlifeacademy1744 I can activate intermittent charging in the BMS settings I assume? Is that also the place to set the percentage? (I thought I saw intermittent charging activated already by default but I will check)
@@andreas4175 it is activated by default. The percentage is in the other Menu of the Parameter settings. I think nearly at the end of the setting page
The comments from people who claim they are top balanced with tiny passive balancers have all been long time users (6 months +). Be interested to see if the delta shifts noticeably within a few days of balancing or if this remains inside a margin of error.
Good on you for being willing to go against your established facts in the pursuit of knowledge. :)
I find your ability to process analitics for Andy's chanel more interesting then the video lol. How did you manage to figure this out?
@@boatelectricaldiy this seems to be some happy accident some how then. I'm only commenting based on the fragments I've noticed by other commenters in response to Andy's videos over the course of time. I don't read all of them, but I do notice as much as Andy that people respond saying "this isn't correct because My Experience is X y z" etc but are often missing crucial details. I think we have all been drawn in to Andy's work because of rigorous real world testing vs manufacturers claims and indeed, challenging and learning from the community.
Always been analytical, it's what I do for the Air Force every day...
Mostly recovering a top balance will take longer, it all depends on the charge current and cell size. When slowly charging, a pasive balancer has more time to do its job. Pasive balancers are not perfect but will work unless the discharge and charge currents are too high. Staying under 0.2c charge rate will make a pasive balancer work good enough.
@ozzietj I thought you might be a secret Andy account 😉. Your explanation is plausable though.
@@boatelectricaldiy I'm a nobody in a sea of other people. Andy's responses have a gravitas, respect and authority of its own that comes with being an established and genuine content creator. Secret/dummy accounts would undermine the intangible value he has so richly created with his viewers.
Hey Andy. I don’t think it’s the different BMS’s fault or your absorption voltage. I’m thinking it’s your aluminum busses giving you problems . The JK has the superior balancer and has faired the best but even that has limitations. I have 3 JK’s that see 55.2volts about 5 out of every 7 days. The typical absorb time is around 20 minutes. About 12 minutes in to absorption the balance is less than .003 in all three batteries. Balance start is 54 volts. I firmly believe that my system has been working so well for so long is the preparation of the terminals and busses. There’s absolutely nothing wrong with aluminum buss bars but the oxides must be removed from contact surfaces without compromising flatness immediately before use. I know you don’t care for antioxidants but that might be coming back to bite you now. The only antioxidant I now use is NO-OX-ID A Special. No metals, not runny, ph neutral and keeps moisture OUT. A telltale sign that you have issues is that the nuts are no longer torqued. Check it and see. Also pull the busses off a problematic cell and have a close look at the contact area for discoloration.
Keep up the good work Andy!
Thanks Karl, the aluminium bus bars are only been used in the middle battery. The top and bottom battery have the stock standard tinned copper bus bars.
Oxidation cannot be an issue here. Remember, all these cells have welded studs and the contact area between the terminals and bus bars is tiny. With the 4Nm of torque applied this creates a perfect low resistance connection (tested with over 200A). Contact issues look different are not related to cell 1-10 in both batteries. It's definitely the HELTEC BMS wich causes this.
Once a month or when ever I remember, I increase the charge voltage in steps up to 3.65v
I've got jk bms, at 3.65 vs 3.45 there is often only 5 or 10 mv difference at the higher voltage if it was fully balanced at 3.45
you would most likely see the same if your bms was able to balance with more current.
So, what in my opinion raising the volting to allow the bms to balance at a higher voltage will only help if the bms can actually balance at the lower 3.45v.
If there is devation at 3.45 there will only be more at any higher voltage and the bms will need to work harder to keep it in balance
Thanks for sharing. I like the idea of a maintenance charge once a year, increasing the voltage and check on the cells.
Yes, correct, we can see the imbalance now in both BMS when I charge higher.
It seems like there are some differences between JBD BMSes, I have a LH-SP20S005 which does balancing both while charging and not charging with the balancing set to “Only while charging”.
Yes, absolutely. This makes the JBD experience so unpredictable.
Once top balanced, 3.45V/cell will be enough with the JBD Smart BMS / Overkill Solar BMS.
The imbalance seems to be large...so it could take some days until it is initially balanced with the passive balancer.
For the initial top balance, higher voltages are good, because you get higher balancing currents I=U/R
Well, all three banks were 100% top balanced but somehow the Heltec BMS created this cell 1-10 chaos for whatever reason.
It will be interesting to find out how much capacity I have 'lost' because of this imbalance... -> next video
looks like a job for the ZKETECH 😁@@OffGridGarageAustralia
I charge daily to 3.55V, and seem to work well. its a bit higher up the curve then 3.45 to seperate the high flighers from the low once.
Still need to set up my BMS to deactivate the active balancers below say 3.4, but who has the time!! i think i'm in that stage of "good enough" and there is not enough reason to sort it out... maybe some day!
If it works for you like this, don't change it. I'm just testing here as I'm curious what happens if I change certain parameters and settings.
Hmmmmm..... Andy, or, anyone... correct me if I got this wrong... You said, the JK bms worked fine with the settings you wanted to run, kept cell deviation fine... Personally.... I would have gotten rid of the Overkill, and, Helltech, ... bought 2 more JK's ... and been done with it..... The definition of insanity is to "Do the same thing over and over and expect a different outcome". Now, I also believe that "calendar" degradation will get to the cells "WAY" before any degradation from charging to 3.5 or3.6.... even ...3.65!!.... but that's just me..... Cheers, Andy...
The channel is not about getting it right or following the path which works.
I'm here to test, explore, learn and share. Hence the three different BMS in the shelf, amongst many other 'weird' setups.
I have set my limit to 3.5V
with the aktive (voltage triggered) balancer I see 2 mv difference over 6x16 cells (302ah)
I have set my system to fully charge once per week ( either if enough solar , or cheap electricity)
works like a charm, balanced, a reasonable voltage imho the best way.
Great, thanks for sharing!
Gutes Video,👍😊
Yes it matters at the higher voltage because it’s only at the higher voltage that the voltage difference highlights the actual SOC difference in the batteries. The fact that the JK with active balance was so far out of balance demonstrates that 3.45 isn’t high enough. I also think the 3.55 or even 3.65v charge voltage would only add additional degradation if you were charging that high with really high currents. The best solution would be to charge with full power (max spec) to 3.45v then lower your charge current to between 2-5amps until it his 3.55 or even 3.65. This would have two advantages. 1. It would work almost the same as an absorb charge and 2. The low current charge would allow the passive balancers to bleed charge off the higher cells.
Nice idea, though what about for those who can not set their chargers to change current (like the all in one inverters its not possible) what can we do to stop the imbalance, also does 150mv actually matter much ? TIA
@@hasger1941 with my 12v stuff I have two custom charge profiles. One where it's max amps to 3.45 and a second one where I limit the charge to 4 amps to 3.55. There has to be a way where you can set your inverter to charge to 3.45 then come back and change it to 3.55v but only give the inverter a small amount of input current. Remember from Andy's tests that there is a very small amount of SOC difference between 3.45v with a long absorption time and 3.55v when you look at it overall. So finding a way to manually provide low current to do that last balance once a month can't be that hard.
Over 3.5V the voltage increase so fast that high or low current make no different on a daily use because the difference will be less than 1% in capacity, what could damage the cells is if BMS responds slow or you setup up the protection incorrectly. I agree with you, it will only add additional degradation. High voltage in a cell on top charge indicates the worst cell and the balancer will take energy from the ones with lower capacity to the ones with higher, that's why giving time for the balance to work will help to put some energy back in those after the good ones became full.
It will be nice to have a BMS that take energy from the ones with lower voltage on charge and higher voltage on discharge, the V Delta will be crazy but the capacity will be the same on all cells and degradation will be slower in the worst cells.
It makes a difference in that the passive balancer that is “shaving” or redistributing power from the higher voltage cell has a better chance to do it if the overall current is 2A-5A than if it is trying balance against a 10-20-50A change current. At the higher charge current the highest voltage cell goes from 3.45 to 3.65 in just a minute or two and hits OVP before the balancer has a change to move enough charge into lower voltage cells.
@@AussieAustrian For max top balance I even lower current to 0.5A but it's only for test and try to get the 3.65V on all cells.
On daily use the faster it gets max voltage the better because you are taking energy from the worst cells to the better and that increases the imbalance, don't give so much importance to voltage but more to capacity of each cell, because the lowest dictates the capacity of your bank.
Great test as always!
I think another good test once this one is complete with data is to...
Top balance a Bank of batteries once, then disable balancing and run a long-term test stressing the battery out (charging and discharging) to see where it finalizes after many cycles. What do you think eh?
Yes, that's is great! I actually touch on that in the next video when we determine the cell drift since installing the battery shelf.
If you find it drifts it just keeps going until you intervene
If balance current/time is too low to correct
Eventually you have a low battery shutdown, enough of those and you have capacity drift as the low cell that gets run down to 0% degrades faster
Time to add a number of small automatic fires extinguishers and some insulated cable cutters to your shop. There's some serious power and mysteries growing in there.
I think they started breeding a while ago...
Big changes coming to the garage to cater for all that...
good video Andy! lots to learn again .thank you. Looking at your disco lights ,one question for you, in your set up, have you ever experience flickering LED lights when powered from the inverter under heavy loads like microwave or coffee machine?
Thanks, no flickering lights, no. But I'm off-grid, so there is no synchronisation to the grid necessary for my inverter.
@@OffGridGarageAustralia so do think that the flickering is caused by the grid ? You are right , I'm not completely offgrid. I'm using solar as an emergency system in case the grid goes off.
@@imag555 Maybe you are getting LED flickering if inverter is supplying something a pwm type load where it has to switch on and off fast. I had that on my inverter when I used it to pwm an ac load on it.
thanks Larry! im getting the flickering only if i make coffee or using the microwave. i dont have ac. i checked the sin wave with an oscilloscope and i can see the wave jumping up and down about 10 to 15 volts . im using a Growatt 3000w TL LVM ES.
@@LarryKapp1
Thanks Andy
Dear Andy! Your videos are very good!
I would like to ask how to set up the OVERKILL SOLAR
on an android phone. I downloaded the app, but it doesn't show live data.
The BMS can be set, the BMS is JDB type. It worked perfectly when the first app was started, but after the second or third start, it did not provide live data. I can set all the data in the bms, only there is no live data.
Thank you for reading!
Regards: Feri
No idea... You can always use the XiaoXiang app which works.
The Overkill does not work with all JBD BMS for some reason.
Thanks for the reply!
I tried the XiaoXiang app, its version called LLT works.
Regards: Feri@@OffGridGarageAustralia
So whats happening to cells 11-16 then? They were still at 3.3x/3.4x volts, whereas 1-10 were 3.5x/3.6x volts 🤔 is there a setting wrong somewhere thats excluding cells 11-16 maybe?
Or are cells 11-16 used as an overflow for 1-10 if they get too high?
That's exactly what my Heltec BMS did to both battery banks.
The question is why?
Faster or more rapid, dendrite growth is caused by higher voltages and by high heat in ANY lithium chemistry..... This has been addressed by people far more knowledgeable than any of us..... Dendrite growth is a result of the lithium chemistry, want it or not. The amount of dendrite growth is dependant on the voltage within the cell and the amount of heat within the cell whether it be because of high charge rates or by high external ambient temps........ I do not know why people choose to ignore this fact.... I too charge my batteries to 3.45V per cell and I can say with confidence that my battery temps ARE LOWER than when charging to 3.55 or 3.65V per cell. I have 10C higher when charging to 3.55v compared to 3.45V.......
Dendritte... that was it! Yeah, lots of Google hits explaining it...
Thanks for the reminder and sharing this here again!
I'm past the 3:00 time mark in the video and you haven't told us HOW MANY AMPS OUTSIDE?!?!?
HOW CAN YOU DO THIS TO US?!?
Oh, sh1t. I totally forgot!
My 280ah 16s pack has a 125 mv deviation at 3.5 volts and in 6 months the overkill bms has done nothing to correct it. The batteries are only discharged to 85% and fully charged every day.
Since I’m only using only 15% of my power each day, if should have been easy for the bms to correct the deviation.
Yeah, I have the same experience with the passive balancers. I wonder if this would be rectified with charging to 3.55V or even 3.6V.
Get an active balancer
@@OffGridGarageAustraliamy guess is that it won’t make a difference at all.
It’s not worth the hassle anyway. You’ve already proven that charging to 3.55v+ per cell isn’t practical because the average battery pack won’t reach that voltage without a cell hitting 3.65.
Even when my 15 amp NEEEEY balancer arrives and fixes my cell deviation, I still won’t charge to 3.65
Hello, how can you have a large number of different BMS, each of them disconnected from the inverter, do they work as an island?
It seems they are all struggeling a bit. Also the JK. Could this be caused because the batteries have 'cycled' a pretty long time in winter but in that time hardly came to 100%, allowing the balancer to do its job?
Yeah, exactly. The lack of balancing time is to blame here. I promise, I will do better from now on.
29C 'spring' - no thanks :)
Wearing socks all year - no thanks 😉
You can come down south. Here in Victoria, Australia, 17 degrees C. Nice sunny days.
Well i did learn that about the bms I have the overkill BMS is and I didn't know that they would keep balancing if they hit over voltage on a cell I always just stopped before they did that I'll have to give that a try
This is just if an overvoltage protection occurs, it keeps balancing. Normally you would not hit OVP though so balancing will stop.
I have raised the voltage here in this test until OVP was triggered and saw that it keeps balancing in this situation.
JKBMSES, I have had two faulty ones so far. Cold down here today only 17 degrees, cloudy at around 1 pm.
Hi Andy, do you remember me? I'm Peppe from Napoli (Italy) the place of sun, pizza and spaghetti. I was one of the guy saying that the charging voltage of your lifepo4 cells was too low, reason why you have unbalanced cells. Now is time to make you changing your idea about seplos bms ! Do you remember my previous message saing that the seplos bms works perfectly fine with my Voltronic Axpert MAX hybrid inverter? Well, you can set your seplos bms in a way it works well with your system. SEPLOS bms (v2.0 10E) has three high voltage sets, normally only two of them are used. 1) The first level is named "total pressure high pressure alarm". Once reached this voltage level set, the bms reduce (via commujication bus) the charge current to 9A after a delay of 30 seconds. 2) second set is named "total voltage overpressure protection" which is a set communicated via bus to the charger controller as voltage setpoint and in the same time, once the voltage has reached, is going to open the charging mosfet. 3) last level set is called "Harging overvoltage protection" ("C" for some reason is missing) which is the last level of protection once reached, the charging mosfet are opening. Now some of you may think: "Why they implemented two overvoltage threashould"? simple! because the second set level (total voltage overvoltage protection) can be disabled as alarm using a flag control on the right side of the settings, leaving on it the only functiolality to communicate to the charger controller the charging voltage setpoint. With those settings the one which is going to work as protection is the third one (charging overvoltage protection) which is working exclusively as protection, thipically at higher threashould of level two. I hope it is undertandable Andy. let us know...
I agree, a retesting of the Seplos BMS (and Pace BMS) once the results are in should be done. Andy might be surprised to find that both BMS's do reset SoC without driving it into protection.
I'll test it again at some stage but the 10E only shows 100% if OVP is reached afaik.
@@OffGridGarageAustraliaRecent 2 videos on my channel disprove that.
@@sarahjrandomnumbers I assume, you're not off-grid? The Seplos BMS have a different behaviour in either scenario. It took us months to find out by comparing XML files and settngs.
@@OffGridGarageAustraliaWhen I'm charging to 100%, I am offgrid, cause it's the solar that takes over from 56.4 to 56.8, and as you can see from the videos I uploaded, the current drops and it resets.
I doubt very much that the battery knows or cares if the power its getting is from the grid or from solar. I could see it being an issue when you're ramming 120A+ into the battery at almost peak voltage, as your system did earlier at 1218, your time.
Where as my system charges 15-20A until 56.4, then solar does around 5A until 56.8 and its absorbed. Then SoC resets.
I guess the other main difference is you system isn't hooked up to CAN, where as mine is, that would certainly explain the lack of slowing the current down towards the peak. All I'm saying is, it works for me, so it should work for you too.
They need more love !!! ❤
Yes, we all do!
As you cycle the batteries, how long are they likely to sit at that higher voltage? I would guess that the amount of time at the higher voltage would be a factor in any degradation. If there is a significant benefit from raising the charge voltage to allow the balancers more time to achieve a better balance, degradation might be less significant if the batteries are not held at that higher voltage for long periods of time.
Well, you need to give the balancer time at this higher voltage. I have them sitting at 3.55V for 1h now. Let's see how this goes...
I'm glad my Neey 4a arrived last week. 😎
I thought that calendar aging will kill the battery faster than the the difference between 3.45 V vs 3.55 V
My thoughts precisely. As long as you aren't 1C cycling every day, shelf life will be the grim reaper of these cells rather than a 0.1v difference.
Yes, exactly. Cycle life does not matter so much. I still like to test things and understand, so...
Andy Elon is recomending 100% charge!
Well, this is purely to keep the BMS and the milage estimator calibrated. Tesla had lots of trouble at the beginning with LFP batteries and cars suddenly stopping with an empty battery. I would still not do it if I had a LFP EV.
And LFP has a much higher cycle life than NMC batteries.
LFP: 3000cycles @ 400km = 1.200.000km
I mean who cares if the battery is then down to 80%
I am charging to 100% once a week
Hey Andy, can we get update about SEPLOS reaching OVP and cell peaking ,i m curious about that system
In the next video my friend...
@@OffGridGarageAustralia looking forwards to 🔋
👍 great video, I am waiting for the results for the next video. Thanks Andy 😉
Yes, the result will be interesting 😉
Thanks for the info John.
All right, Peter!
You can't read balance voltages while charging and discharging - only at steady state after a while. When current is flowing, either way, the cells internal resistance influences the voltage.
You can still balance as the current of your load or charger is influencing all cells at the same time in a series connection, so the delta will still be visible, not the same but still in the same relation to each other.
And Daly balances only while charging. They clearly know how balancing works?
heltec-bms
16S 250A 3.2V Same Port
Charge protection voltage: 3.75V
Discharge protection voltage: 2.1V
Charge release voltage: 3.55V
Discharge release voltage: 2.5V
Balanced voltage 3.55V
Balanced current: 95MA
Long-term continuous overcurrent value: 250A
Instantaneous current limit value: 1500A
Dangerous settings for LiFePO4!
Charge/Discharge Protection Voltage needs to be accordingly to the specifications of your cells.
I do not think the extra capacity is worth the extra degradation. There are many scientific papers showing LiFePo degradation by voltage ( calendar aging ). Personally i set the high limit on all my projects at 3.5 volt per cell and generally have under 30mV deviation. Less then 1% capacity should not make a difference in the usability of a system. I do build systems up to 100kWh with huge loads. I found the sweetspot, after a lot of testing at 3.50v. ( 3.45 made deviation less stable, where day to day differences where acouring more offten )
The problem with charging to 3.60 - 3.65 is hitting over voltage protection,. In a multi battery pack this will create an OVP and will disconnect one after the other and ending up in one taking all the charge at the end. ( not everyone has victron or can/serial/rs485 comunication to prevent this depending on the usecase and budget ).
So in general it is better to to be around 3.5v and set OVP at 3.65 leaving a 150mV deviation space to keep the entire multi battery pack active.
That sayed it is still great seeing you doing all these tests, proving concepts ;)
I think there is something that you're missing with the balancing on these I don't think you can just go right to 3.65 with 1 millivolt deviation and say that it's good because I've noticed that if you do that and then you get it to below three volts and then recharge they'll be different every time I think that's why the BMSs have such a slow balancing function is to alleviate this sort of rebound thing that they're doing where they bounce around what I mean by this is you can take out so much power out of say cell 1 because that one was high and then the next time that one will be way low but you didn't get it low when you took out it was perfectly in balance with the rest
Maybe you could test this have one cell that is higher than the rest and discharge that one say 1 amp or maybe just till ot has 10mv or so with the rest and then cycle the battery and see if that one is still higher or is now lower then the rest
What I mean is if you take out say 1 amp for a high cell to get it even with the rest I've noticed that by the time you get it even with the rest and do a cycle then all the sudden that was way too much you took out and so if you take a little bit out of the other cells to make them even and do a cycle then all the sudden you took too much out of those too it seems that you got to take a little bit out and then do a cycle That's what I've seen anyway
I don't really think that charging to a lower voltage prolongs the life of lithium iron phosphate like it does with lithium ion The life expectancy is already so high anyways even if you're doing one full cycle per day it's still likely to just deteriorate due to the age of the cells and the age of the equipment rather than the actual batteries wearing out by cycling i haven't seen any of the documentation says anything about you get more cycles if you charge to a lower voltage
Yeah, that's what some other viewers said as well... Maybe 3.45V is too low... and 3.55V gives us a better balancing experience.
Hello ihave jbd bms and i turn off the charging balance but it still not balancing at all
It will only balance if it shows 0.0A, if charge balance is off. If you turn this on, however, it will only balance while charging and stops when there is 0.0A displayed.
In theory, charging LiFePO4 batteries can charge to 100% voltage with no issues, no degradation.
I know the theory... 😉
Are all BMS calibrated cell voltage are correct .
So i tell are all voltages the BMS reads are the correct voltage of the cells it measures?
Yes, all correct and confirmed in all three batteries.
Porque se complica usando diferentes BMS , reemplace todo por una sola marca
Sehr informativ.
Mal eine Frage zum Master laderegler.
Ich habe den smartshunt als Master im bluetoth Netzwerk. Sollte ich das ändern und ein mppt als Master machen. Wegen den setting setzen.
How can you make the shunt a master in the Victron BT network??? It picks always an MPPT and all other MPPTs follow this master...
Greetings Andy from sunny Portugal, Europe. Only discovered your channel a few weeks back as I'm trying to garner some education on charging Lithium batteries. Have now watched all your videos and wonder is it possible you are being too pedantic about the battery voltages, looking at them to three decimal places? (to a thousandth of a volt) Surely one decimal place would be fine if all the cells are 3.5V (for example) then that should be good enough. Please tell why it is so important to balance them to such a high degree?
Welcome to the channel first of all and greetings to sunny Portugal. Been there many times, beautiful country and people.
100% not important to balance that precise and also surely impossible. This is just the testing I do, so working with these numbers as they come in from my tests.
A 50mV delta at 3.5V is quite acceptable in a 16s battery.
@@OffGridGarageAustralia I'm so glad you have clarified that it was putting me off buying a Lithium for my next battery
If you actually analyses individual cells charging characteristics you will find that they follow their own curves at the higher end. I've seen two cells both at 3.4v, then #1 gets to 3.5v first, then #2 actually seems to accelerate and hit 3.6v before #1. In my setup I charge to 3.55v and balance at 3.55v - basically it's the only way to balance as every cells behaviour is slightly different - basically you only balance those above your design target.
That's why you set a balance start voltage. 'Wac a mole' is how it works.
@@OffGridGarageAustralia I followed your 3.45v for a month or so and noticed far too much balancing going on. Since moving the balance and target charge voltage to 3.55v it all seems happier and I'm getting a lower deviation, what I'm trying to say is that at 3.45v I seemed to be balancing too early and probably balancing some cells prematurely. Also, it seemed to take a week or so for cells to settle into their new home voltage - I liken it to froth on your beer
@@DrJGDCharging to 3.55V has certainly benefits in terms of balancing and makes it much easier and quicker. The question is: is it necessary though to have the battery THAT balanced?
Hell Tech😮😮😮
Is there any way to DC-DC charge a Tesla? DC -> AC -> DC brings conversion losses twice.
Not with anything that Andy has, remember that the Tesla pack voltage is like 350v.
But losses don't really matter when you're getting 100% of your power for free, cause even with a very liberal 50% losses (probably more like 15% total loss), you're still paying 0 for the electricity.
I do the same when we have negative pricing for electricity here. Normally I charge at 15a cause my multiplus is the most efficient there (93%), but when I'm being paid to burn power, 35a charging turns on with it's 85% efficiency.
No way to do this at home. You could buy a $70000 charging station though but guess what, it will be connected to AC as well.
The losses are no problem as the energy is generated green and free.
Heya, I gues it dipents of your situation no instalation is the same.
I have already asked this question in the video before but... The first relay contact of the PACE 200 A BMS switches to continuity in the event of an alarm. Couldn't you disable all alarms in the parameter settings except for the pack overvoltage alarm? Then you could turn the active balancer on and off via the relay with the pack overvoltage alarm setting. Personally, I don't need these alarms anyway. Then either turn off the red flashing LED as well or take it as a sign that the active balancer is working.
Yes, that could work for the higher voltages but what when we have a low temperature alarm, a low voltage alarm. It would trigger the balancer as well.
You can disable this function. There are check boxes and it does not disable the temperature protection. And the undervoltage alarm is below the shutdown voltage of the active balancer.@@OffGridGarageAustralia
@@karisianschwermer6464 But the check boxes disable the whole block of functions. So, OV alarm, OV protection, OV recovery and OV time delay.
I think you can just set the alarm higher than the protection value and disable it.
I will try it today... Of course, this would not be not good if the whole field with the checkbox would be disabled @@OffGridGarageAustralia
Hi Andy, just watched the video. And found out that... Just have running my own battery with a JK BMS and I see that you have a wire resistance of 0.152 and I have using the litse bus bars an I have 0.048 and 0.050. Will this make so a big difference? And I have also the max of 55.2V on the battery. 15kWh.
For me too, with my JK BMS 16S the resistance is 0.050 or 0.049. With my JK BMS 8S the resistance is all at 0.038. All my lugs are welded. On the other hand, Andy's cables are elongated and pass through a connection box.
I have one of the very first JKs. The one which needs a jump starter battery to fire up....
If the bus bars are to blame, it would show a different resistance if under load than in idle. That's not the case for me though.
Are you just about to prove you worry to much about balancing? :D
Also sunny here at the other side of the world, and full battery by lunch and did some balancing - down to 60mv now @3.525/cell and that's basically all in cell pack 4, others are within 20mv (JBD 50ma passive). I suspect you'll maybe find 3.55v/cell triggers OVP whereas 3.525v/cell doesn't shut of charge /charge balance - certainly on first full charge for a while. At least, that's what I find on mine.
I'm not worried about balancing, I'm just curious what will happen.
@@OffGridGarageAustralia and I'm also curious if you again prove the similar conclusions I've come to from using my system. Its good entertainment. Keep on doing your thing.
56.8V vs 55.2V?
Is the added 0.5% SOC significant?
That's not the point here. I'm not charging higher to gain more SOC.
I think the voltage is irrelevant , the amount of time it spends at the CV stage is what matters ,ie you need to actually have more balancing time ie people recharging their batteries full everyday less likely to have unbalanced packs
the less frequent you charge full the bigger balance current you will need
people that think 0.04watt difference between 3.45v vs 3.65v balancing will make an earth shattering difference are just too optimistic 6% increase in balance current realy
Yes, the more often and longer you balance, the less deviation you will have.
@@OffGridGarageAustralia yea so a lower charge voltage may actually work better than a higher one as long as it is over balance start voltage
Especially on bms that only charge balances
Higher voltage / charging current makes the CV tail short
While lower stretches the tail
meaning more balancing time
How do you choose which charge controller is the master?
The DIP switches at the front of the batteries.
what C charge rate max do u advise ?
Optimum charge or maximum charge rates for LFE cells can vary depending on design and manufacture. I've seen between 1C to 2C as max rates for 100ah to 280Ah cells, with 0.5C as recommended, so best to check specs for your application. As long as cell temps don't rise above 40C during continuous charging or discharging, is generally considered safe, with 60C being the limit, and some tests showing long-term degradation at 45degrees C to 50C. So best to look at max rated charge and keep an eye on temps both.
@@jackoneil3933 am charging at 0.2 C,, ty
@@margarita8442 Below is an excerpt from a my post in the main section. I'm using 32700 can cells (Like long D-batteries, not prismatics). They are rated at up to 3C charge to 80%. and when I started charging at .3C to 1.5C , up from only 0.1C to 0.2C ,the packs seemed to preform much better and gained about 10% capacity. I suspect that even though they were reaching 3.5v per cell and adsorbing for hours, they might not have been fully or deeply charging. I suppose it might be that the chemical or Ion structure was not being properly re-formed at the lower charge rates, but I don't have enough to confirm:
"- Does low charge rate degrade performance? Last year on my test packs I was slow-charging between .1C to .2C to 3.40v per cell to try to preserve cell balance and life, and my 3, 300 Watt-hour packs were delivering about 250 watt-hours, this year I've been charging at 0.5C to 1.5C to 56.5v for almost 200 cycles, and the packs now deliver 280 to 310 watt-hours each, and with a noticeable increase in torque and acceleration, that seemed to occur after charging at higher current, so I wonder if LFE cells loose performance or don't fully charge at lower currents?
Finally, I've been charging a 3.2v 1S, 24AH ebike booster pack, that use 4P 32700 LFE cells to 3.75v at .3C, and after 400 cycles the pack is delivering about 8% more capacity than when constructed two years ago, so at this cycle level I'm not seeing any degradation but the pack rarely discharges above 1C and mostly at 0.2C to 0.5C discharge.
Personally, from what I've read and my limited testing, I question if high-discharge rates at elevated temps may degrade LFE cells more than gently charging to higher voltages could result in more cell degradation, some older small-scale Chinese university research testing seems to suggest that, however newer LFP chemistry and materials improvements could have improved that."
Here's the title of one of the research papers from a Chinese university I mentioned:
- 'Analysis of Lithium Iron Phosphate Battery Damage' - Atlantis Press
Charge-discharge experiments of lithium iron phosphate (LiFePO4) battery packs have been performed on an experimental platform, and electrochemical properties and damage mechanism of LiFePO4 batteries are also analyzed in extreme cases. Our results indicate that over- charge has little impact on utilizable capacity of the battery in the short term.
Let me guess the back batteries different cable length to the balancer yes it measures with 0 amps but it charges less because of different cable loss
Nope, wrong guess, that would not matter at all, the difference would be very very small.
Cell 1 is the one closet to the BMS, so has the shortest cable of all cells.
@@OffGridGarageAustralia ok just trying to think of reasons
@@dennisbrok9335 Thank you.
why not add 3x NEeeeeeeeyyy 4A balancer, and start above 3.49v with balancing...? or above 4.46v....or 3.51v :)
I'm testing. Explained here: ruclips.net/video/DXgN9Q60KYM/видео.htmlsi=1ESTi7_DYRFsUZ_z&t=1212
I charge to 3.53v and I have the active balance running 24/7
Hey Andy!
Hello 👋
My causin Bought LiFePo4 36250(i think) 3.2v, he bought 32 of it and put them in series and parrallel to get ~13v we use 100watt solar panel, and a pwm 10amp. But just 20days afterward each one malfunction. I think it overcharge, now only 4 is left . The float was 13.2 if I remember correctly but am ignorant of the correct setting for this type of battery I just knew that its different from flooded battery am used to. I wonder if the battery was deffective or just the setting was wrong and its human error that cause it. *sigh
If your cousin didn't put all cells in parallel and fully charge them before assemble the pack should get them out of balance but to end with only 4, seems that he didn't use a BMS and went over 4V with some cells. BMS are necessary to protect the cells and you.
@@CantFindInRUclips ohh BMS? I see. We thought its only necessary to use a solar controller. I'll see to it. Thanks.
well, dont, use iron-air fuel cells instead, then make metal (charging batteries) with the solar/wind/water energy
Nice I wish I could afford big server rack Lithium batteries unfortunately I'm poor lol so I'll just keep buying each individual cell..
That will work the same way eventually.
😎
You can never have enough blinkenlights
Yes 🚥🚥🚥🚥