The Final Word On Grade B - Lifepo4 cells Grade A vs Grade B - SFK
ฝัง
- เผยแพร่เมื่อ 13 มิ.ย. 2024
- Episode 1 - The issue: 0:00
Episode 2 - Top Balance: 4:12
Episode 3 - Cables & V-Sense: 6:16
Episode 4 - Cell 1 Test: 7:40
Episode 5 - Cell 2 Test: 13:50
Episode 6 - Cell 3 Test: 18:04
Episode 7 - Cell 4 Test: 19:35
Episode 8 - SFK EV Grade Cell 280N: 23:17
Episode 9 - Conclusion: 26:11
In this LONG video, we show what we deal on a regular basis and why we refuse to ever carry grade B cells regardless of what everyone thinks of them.
While it is true, that you may get some grade B cells that are "OK" its just as likely someone else will not. It doesn't matter who the vendor is, or which batch; all grade B share 1 thing in common:
THEY ARE ALL OVER THE PLACE: Some are just short of being grade A, some are potentially problematic cells that may seem ok for low amp use, and some are just terrible and will ruin your pack as is in the case situation. A customer bought one of our V3 kits but already had cells from an Alibaba seller; they kept having there BMS shut down during charging and or discharging. Despite initially RMA-ing the BMS twice, our customer still had issues and finally they sent the cells and kit to us so we diagnosed it and found one of there cells was causing all of the problems.
We took this opportunity to show you what can happen. This does not mean it will happen to everyone, in fact if you by grade B on average you will get a cell that is generally between what a EV grade A is and something that is just garbage.
Most people will never know the difference until the day they actually try to put a load on it. They will also found these issues lead to rapid degradation and other premature aging. They cheap comes out expensive, so choose wisely.
We already explain the difference on Grade A vs Grade B in this video:
• EVE Lithium Iron Phosp...
Grade A Cells available form us: www.sunfunkits.com/category/2... True EV grade with complete manufacturers test report and all data columns, (Unlike the sheet that is conveniently missing the case ID and IR 2/3, Volt2/3 from other sellers claiming to have EV grade Cells).
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Episode 1 - The issue: 0:00
Episode 2 - Top Balance: 4:12
Episode 3 - Cables & V-Sense: 6:16
Episode 4 - Cell 1 Test: 7:40
Episode 5 - Cell 2 Test: 13:50
Episode 6 - Cell 3 Test: 18:04
Episode 7 - Cell 4 Test: 19:35
Episode 8 - SFK EV Grade Cell 280N: 23:17
Episode 9 - Conclusion: 26:11
Thank you for making this video, so more people can learn the difference between A and B cells
Very interesting video, thanks for the information and demonstration.
Very very informative and interesting video. It’s an eye opener. Thanks
Great demonstration!
Finally a correct measurement with V-Sense switched on 👍
Good job well done thank you for that!
thanks !! i learned a lot !!
Thank you very much for this video and sharing the information!
I was wondering if the internal resistence of these cells were OK?
Or is this also not a good way, to rule out bad cells...
Great video and information. Thank you! I went through some quality issues with Basen as well, so their cells are varying a lot. Not saying other re-sellers are a lot better, but maybe a bit better. I'm working on it... 😉
Basen? who is that? ;) These were cells provided to us by our customer for testing due to issues (as explained in the video), but we have similar stories from other vendors, but as the title of the video states, this is the final word from us on grade B, we have to move on to other things.
@@sfkenergy he mean shenzen basen
Aka basen green
Ohh Andy you're also here😂
@@netrocker9990 Big supporter of SFK 💪
This explains a lot. thanks
Glad it was helpful!
Heya, really nice test
Great insight! Nice 2000$ tester you have there. You can do low cost testing by testing them with a bms in 4s config with different loads. If you use a 12v100amp battery tester you pull 25amps per cell and check you cell voltages in the bms app ?
Good idea for the average Joe to get an idea of capacity, but nowhere near as conclusive as this high amp test Im afraid. These high amp tests help show us the real state of health, id like to see him take it higher and see how long he can max it for, as this is experimental testing to prove data, we need to test the extremes, not what we would do in everyday use.
Good vid, nice test, I didn’t see any Internal Resistance measurements, unless I missed that, and I think he should have pushed the limits a bit more though, I think a good cell should push 1C (280Amps) for 30 seconds or more. Cheers
Thx for this great video and for eleminating the critique points mentioned by others. Do you have an idea since when this is happening? It seems that in the beginning of DIY lifepo4 battery building there were less bad cells around - or is it just: people were not aware of this problem? What do you think? From my perspective this started somewhen in 2020 when the demand for lifepo4 cells went up, because more and more people started their DIY battery build projects?
And what do you think how theses cells will behave in a battery? Will they show the same massive voltage drop or an equivalent voltage drop if those cells are connected in a battery? I think you do not want us to send all our bad Grade B cells ;). Would be nice what we Grade-B Warriors have to look for, because most of us use only low current capacity testers ;).
Very fine equipment that you have there in your lab! I wish i had that nice Power supply :-) I build my own from old server PSU and modified it for adjustable voltage. But i only could achieve to have it adjustable from 36....52 VDC but it can deliver more than 120 Amps, its a 6 kVA supply, originally for 42 V. Hard to find a low voltage PSU with that amperage! Also the DC electronic load is fantastic! If you have such equipment you don't have to worry about Grade A or B 🙂
29:09 seems like "Shenzen Basen Technology, Co Ltd" written there... Hmm this suck
Great video. I sent you an email. We need to get this word out there more.
I'm just getting into this stuff, so I'm somewhat stumbling around. This is a very useful video. Ij ust got an Elefast 100 Ah Bluetooth-enabled battery. I'm still waiting for a few other components which will arrive soon. The app lets me see the real-time voltages of each cell along with the amp draw for the battery. I'll put some loads on it (up to 100 amps, as high as the BMS allows) to see how the cells respond. If they are crazy, I'll return the battery, but maybe they'll be ok. Having that monitoring that monitors the voltage of each cell will be really useful.
Great video and explanation! I still see a value for the good grade B cells IF the price reflects it but unfortunately the sellers charge 80-90% what you could buy direct from EVE for! $35-40 a battery would be a deal…$150 a ripoff!!!
HP8182 = Awesome! 👍
Are the 304 a better bet?
Any warehouses in Europe?
So basically if you get 15 almost A grade but one G grade when running together is going to screw the whole pack right?
Yes and then you have to buy more. Certainly some people are lucky and get decent grade B cells while others are not so the rule with grade b is to buy 10-20% more than you need to remove potential bad ones.
@@sfkenergy thats why I purchased 4 cells more than the required for my diy. Still a great bang for the buck. At the end, this B grade stuff is a good deal for solar applications.
Finally got my ZKETECH 40A tester with sixteen non-automotive grade 304Ah batteries from QSO that I bought a while back. They were produced towards the end of June 2021.
I charged the first battery to 3.55 and switched to 3.65 (CV) when it hit 39 amps (then stopped charging at 1A). I was surprised that at 40A (CC) discharge it descended so fast to about 3.3V (five minutes or so). But so far it's 267Ah at 3.17V. Probably not great, but should be fine if I double or treble the parallelism... To be continued! I guess for storage, if you keep below C 0.20 you should be fine, but I need to root out the worst cells and ensure I have about 20% extra to replace them...
You will need manually adjustable BMS controller with these types of cell.
questions for you. what if the cell passes the v drop at amp load but fails the AH test (labeled 100 tested 80)? mislabeled? also how does the type of insulation change the current a wire can carry other than when the insulation melts off? to me - if the wire gets hot when using then the wire (conductor) it too small. heat =wasted power, high resistance, voltage drop
We have rarely seen it Fail the WH test, usually it will match the WH on the Cell's QR code which (around 896WH to 900 WH). Depending on the cell Chemistry the LF280K 896 WH will settle to its rated capacity very quickly, while the LF304 will get there slowly (but with in 20-30 cycles even the LF304 will be at its rated capacity which is 972 WH.
Grade A cells are always rated based on the ability to hold voltage under load, not the amount of current capacity you can draw from them. At low discharge rates usually you will find grade B is able to put out the same amount of capacity as grade B. BUT grade B is degraded cell it has internal shorts and other issues which means it can not supply power output properly, this will lead to accelerated aging and other issues, sadly many people will find this out years after they have had there cell.
@@sfkenergy Yes, but at less than half price, it seems like grade B still comes out ahead. If it fails in less than 5 years, the warranty covers it, though I'm not sure exactly what the warranty covers.
Thanks for the comments, however, in our experience we have NEVER heard of any grade B seller ever honoring warranty... So best of luck and hopefully it will work out ok.@@slydog7131
@@sfkenergy I think you are probably right about that. With the econo batteries people are pretty much on their own. I certainly wouldn't use them anyplace where high reliability is needed or where they are frequently cycled. I recently bought an Elefast mini battery ($206 on Amazon + shipping). I've been testing it. Capacity is as rated. Testing with an 86 amp load showed stable voltage and a maximum cell voltage variation of 29 mV, but mostly it is 2-3 mV The Bluetooth app lets me monitor each cell and battery state. It also has low temperature protection. A teardown video on TH-cam shows an impressive quality build, at least that's what it looked like to me. It seems to be an outlier for econo batteries. Many teardowns I've seen of batteries even costing ~$350 for 100Ah looked pretty shoddy. So far I've been happy with the Elefast mini. I guess I'll see how it does over time.
I have no way to tests these things and wanted to try to build my own unit. .. People lie ... and for some reason they are running amuck ... so I may have to bail. How do I know to get good cells....
See this video: th-cam.com/video/l0D6briSN3c/w-d-xo.html all certified cells comes with a manufacturer test report that list each cell individually and shows it test data. All cells sold by Sun Fun Kits are certified and have there test report on the labels.
I had always been a little skeptical of Sun Fun Kits but that EV cell test was all I needed to see. Holy Shit. After reading over and over and over from people online that we can't tell the difference between a Grade B and Grade A all it takes is a very high discharge test, just like you would when testing questionable 18650 power cells you bought from a source you don't trust. Hit em with the banger and see if they can survive.
Nice test, thanks for this info. I would have liked to see what the IR’s were of the cells, Im guessing that the suspect cells had higher IR. Andy’s ‘Off Grid Garage” has recently made a video about this Grade A & B dilemma , it would seem that there are only pass & fail cell that EVE make, ie, they fail to make EV’s stringent requirements, so they are on sold as failed cells and RE marketed to us as Grade A cells. As you say many of these cells are fine almost EV grade (80-90%), but yes, there will be some dud cells along the way, probly from all resellers, unless they are sourced directly from EVE as EV grade cells and they will have proper documentation to show this with them, & their price will also reflect this certification standard. Soooo, there is no A & B, just pass or fail and EVE only sell EV grade to the public if at all. That is my understanding, which makes more sense than repurposing batteries would be a waste of time. If you buy from china you are always taking a risk, but check ur cells & if they are down, the best u can do is try and get a portion of ur money back. Cheers
I think the time wasted and then having to go and buy replacement cells for you grade B pack is extremely unpleasant. Secondly, the life span of failed EV cells is unknown, some speculate 1/3 others say 1/2 of regular cells, this is something we will find out as time goes by, However, the 10% degradation after 75 cycles that Andy had is not good at all.
Ultimately people must realize these grade B cells are not doing what they were supposed to do, so all data sheets and other information does not apply. It is a risk that you are taking when buying grade B.
18:13 Hmmm what could that name be?
To properly test a cell, you need to hold the load until cell exponential overpotential voltage decay slump levels out at equilibrium for the given load current which takes one to three minutes at 25 degs C. After reaching equilibrium for load test, it will take 3-5 minutes to recover to open circuit voltage again after load removed.
You need to wait until OCV reaches equilibrium again before starting another test at a different load current.
You should always state the temperature of the cell when starting test. Colder cell will show worse performance. Below 15 degs C (60 degs F) it starts to become a factor in the results.
Matched cells should have nearly the same voltage slump at equilibrium for same load current and temp.
That was not what is being compared in this video, nor is this a full capacity test of cells. This was a demonstration to show variance between grade B cells. Not sure what your intentions are, but a common theme we find from comments such as this is to imply the grade B cells are not that bad and because of our testing procedure we put them in a bad light. We used the same test procedure on all 5 cells and provided the results. This time with V-sense, with continuous cables; no amount of massaging will change the fact that grade B is inconsistent and unreliable supply which should only be used by enthusiast that have the time to sort out / weed out cells. For everyone else, Certified cells are far more reliable and provide peace of mind.
Thank you for this video, and these tests, which make us understand the difference between good Cells and less or even much less good Cells.😁
I completely approve of your comments, concerning the purchase on Chinese platforms, like Alibaba and others.. it is much too random, and my opinion is that they cannot be trusted..
I test all my cells at 180 amps for their full capacity to confirm their 304AH. I have never had a problem like you are showing here. It's very interesting to see. Did your customer contact the supplier about the defective cell? Sometimes things fail and the dates given indicate that the cells are still under warranty.
There is no such thing as a warranty on Alibaba, only a $5.00 discount on a future order. The customer was left frustrated and without any recourse. We see a range of issues like this routinely many times they assume it is an issue with our kit because we are the only ones they can actually call and complain too. Although the issue shown in the first cell (garbage grade) doesn't happen as often (about 1-5% of the grade B cells are like this) most of the cells are like Cell no. 2 and no. 4 they will not hold voltage under load once you start hitting 150A.
Your 304 is larger capacity than the 280 so it can handle 180A better. Or if you gotten grade A cells (with full manufacturer's report, then you should be able to test at 180A without issue)
Either way, EVE has been marking all of there grade B cells with a Letter B on them, so hopefully now consumers will be aware of the issues.
@@sfkenergy it makes sense that the 280AH are more prone to problems. Same sized case as the 304AH and way less capacity. They would have had to fail much harder. It's probably why I've not had a problem so far.
It makes me wonder though, I haven't pushed the 304 amp 1C rating claimed yet. I've done short bursts to 250a but never the full 1C they are rated for. Guess I have some more testing to do. Easy enough monitor the voltage without the BMS for the test.
Wouldn’t it be funny if the 280 AH cells were just bad quality 304 AH cells resold to make profit on bad cells
This is not possible the LF280N have LF280 on the QR code and AH listed while the 304 Also have the model listed on the QR code.
👍
Do you sell grade B cells?
No quality is inconsistent and customers will get bad cells some will get decent others will not we tried this when we first started and realize this whole thing is a scam and not worth the nonsense. Plus we would liable unlike many Alibaba sellers who could care less.
I'm confused why you keep saying they can hide behind a 40amp test. When you hit the cell with 100 watts that was less than 40A and the voltage drop made it clear it was a bad cell. How would they hide behind this? Is it because a Constant Power test is going to show more amperage being pulled on a bad cell and thats an easier way for people to realize its a bad cell? Like people aren't paying attention to to the voltage when they hit it with a constant current?
I can't see how a complete discharge with CP would end up much better than CC
1 way to hide is to parallel them with other cells this is very common with 200a batteries where you 8 cells but only 12 volts.
The bad cell is not very common even amping grade b but every now and then you get a cell like this. It will probably even test to 250ish AH in a capacity test.
from the position of the qr codes..these are fake qr codes. the original qr code has been scratched out
Why are there so many low grade ( failures) generated in mass production of LFP batteries? Precision manufacturing shouldn’t result in such high losses. This is very concerning.
Hi, we are in period of rapid growth in the battery industry, so companies are still perfecting manufacturing techniques. This should approve in the future but for now instead of recycling failed cells (which almost all manufacturers say they do) they are instead auctioning off failed cells which are bought by wholesalers and then sold on sites like alibaba where unsuspecting buyers get them thinking they have gotten a deal.
@@sfkenergy thanks for the explanation.
I have a feeling that Mr RAY may soon be eating some SUNFUN CROW....seams like you guys really have your shit together....👍👍👍👍👍⭐⭐⭐⭐⭐
Rather pay more then buy a kit, too dumb to build one anyway.
If you could buy all the cells from the same batch...That would cutout all the shenanigans they pull....
this is why its called second life!!!! .. its part of the circulation
Yes, but what are the people selling these cells calling them?.. Grade A perfect Chery on Top Cells... So if they called a spade a spade everything would be fine.
its the cost raising the main problem!!! china sending one or 2 bad cells was always a common!!! even for me in eurpoe that we re 2 years back in lipofe4 products!!!!!! some stuff US saw 5 years ago we still wait to import ..