How to tell if EVE cells are A or B, and does it really matter?

[apctjb]

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NIce! Thanks

No doubt this is going to pose a challenge to the EVE resellers which have been purchasing B grade, and then reselling them as Grade A if they pass there own test standards. I wonder if placing the B over the QR code makes it impossible to scan the code . Have you tried?

 

[Theo74]

Nope, I just got this picture, but I actually thought the same; would the QR code still be readable.
Thinking simple this should be the case, otherwise the complete QR code should be useless then.

 

[Alkaline]

I doubt that they are grade 'A' unless you buy directly from EVE at premium price or from Amy Wan of Luyuan, she is supposed to have direct supply with EVE.

I would avoid 280K matched & batched from Luyuan, or any other grade A seller selling the 280K. If you want grade A than get the 304 grade A from Luyuan or just get the grade A- 280K. I don't recommend anyone pay the premium for the 280K grade A, even Amy wan said the same thing to me that grade A- 280K is almost the same as grade A 280K. With grade A 280K you will barely get 280 AH, yes I have spreadsheets its barely meeting capacity. If the 280N were still being made then I would say Yes get Grade A 280N, those all pulled 290+ and kicked butt.

On and off again you keep hearing about hoe EVE had a big order get canceled because of quality issues and the 280K.

Finally if you look at the latest document: https://diysolarforum.com/resources/eve-lf280k-s04.296/ So I don't think the 280K is an EV grade Cell , its meant to be a storage grade. Starting form page 11 if you search for: GB/T 36276-2018 you will find this is a test for Lithium ion battery for electrical energy storage)

This compared to the 304:

EVE LiFePo4 LF304 (3.2V 304Ah) Product Specification Data Sheet (version B) 2020-06-18

Data sheet for EVE LiFePo4 304AH cells received from Shenzhen Qishou Technology Co., Ltd

diysolarforum.com

that has this test: GB/T 31485-2015 <《Safety requirements and test methods for traction battery of electric vehicle》

So the 304 is an EV grade Cell and the 280K is an ESS grade Cell...

Well if a 280K is already an ESS cell (which we normally call EV grade B cells) then what is the grade B version of that? Grade C? Cockroach Grade?

 

[Alkaline]

Like this:

how much you want to bet EVE stops doing this when no on buys there grade B stock. Docan just switched to CATL 280 probably for this same reason.

 

[RandyP]

Grade A or B LiFePO4 cell designations are a reseellers fantasy designation (companies that buy failed cells at auction in big lots from cell manufacturers). The buyer looking for something for nothing brings this fantasy to the market table. The only true Grade LiFePO4 cell designation with a nation wide industrial standard in China is an 'Automotive Grade' cell .
If you want a excellent LiFePO4 prysmatic cell buy an 'automotive grade' cell with manufacturers test data sheet that traces back to cell QR code on the cell. Pay the going price. Otherwise you are just rolling the dice.

 

[apctjb]

If you want a excellent LiFePO4 prysmatic cell buy an 'automotive grade' cell with manufacturers test data sheet that traces back to cell QR code

Very true; but what if you are after the lowest system $/kwhr storage delivered over the useful life of the battery. Is that achieved by purchasing authentic automotive grade A at a premium or something else sold at a discount? Has anyone done the analysis?

 

[apctjb]

Okay, quick comparison of cost of $/kwhr of Grade A vs Grade B.

Assumptions;
Grade A $200/cell, 6000 cycles, 280ah/896whr storage. $/kwhr over lifetime of battery=$.037, call it 4 cents/kwhr.
Grade B $110/cell, unknow cycle life, Unknow capacity.

First lets look at cycles.

You need to get more than 3300 cycles from a 6000 rated cell to achieve a lower $/kwhr cost. If you get that you are money ahead.

Next capacity.

You need to get more than 154 Ahr out of the 280ah cell to achieve a lower $/kwhr.

What is best depends on individual preference and circumstances, draw your own conclusions.

 

[SolaroSsaurius]

My 2 cents...
I think that you are not taking into account that Grade B are more prone to runaway, hence rendering the pack unusable/ less usable / reliable

 

[apctjb]

I think that you are not taking into account that Grade B are more prone to runaway, hence rendering the pack unusable/ less usable / reliable

Yes, this is a simple economic analysis which does not attempt to factor in potential cost impacts of differences in reliability it there are any. Frankly not sure how to quantify these cost as for some a runaway cell has no cost impact, others it will.

 

[RandyP]

I think you have to thnk of a non-automotive grade cell (a failed cell) as a package deal. Too many unknowns to expect much from a battery made of these reject cells.

 

[apctjb]

Too many unknowns to expect much from a battery made of these reject cells.

Unknows like less capacity and cycle life. What other unknows are you referring to?

 

[jimjoe]

Unknows like less capacity and cycle life. What other unknows are you referring to?

For instance, such unknowns:

B cells are the failed to pass certification. Why they failed? There are always some mismanufactured items on production lines. Sometimes you have mismanufactured items, that are still "usable" for some purposes. Like you can see on the video, there is a different reactivity of the cells on current draw and how they recover. In the "storage" use, when you have fairly low cycling (50-150 a year) and low currents, quite much time pass before a mismanufactured B grade cell dies - people rarerly, in this type of use, get to the numbers of cycles and currents the cells are supposed to survive/last - the mismanufactured B grade cells are seen to be fit for purpose of energy storage (especially DIY). Different situation is with electric vehicles - where cycling can be frequent (people driving cars as part of work) and where also stress on the batteries is much higher - high currents going in and out of the cells in the frequent cycles.

The big problem with mismanufactured cells is that there is no one reason why the cells fail pass tests. They simply are not meeting expectation of a final product and are considered waste. The waste is bought by resellers like Docan (who are liers), selected and sold to us as a "A grade" cells. Only after such malpractice manufacturers see damage these resellers make to them and start marking cells - like EVE did with the "B" mark. Hope this marking by manufacturer will be a standard, so it will be harder for Docan and others scam us.

Like this video, because it shows how different the 4, "B grade" cells can be - one of them nicely keeps voltage despite high current draw while the other barely hanging on... You simply do not now what you get and one cell can cause lots of pain in your system. If you are a sole DIY and can manage failure of system - which most of DIYers can in their personal use then you'll likely live. If you are building system for someone or take on yourself risk of guarantee or need a solution you want make and forget about, then use of B cells is a risk to your activity.

 

[houseofancients]

For instance, such unknowns:

B cells are the failed to pass certification. Why they failed? There are always some mismanufactured items on production lines. Sometimes you have mismanufactured items, that are still "usable" for some purposes. Like you can see on the video, there is a different reactivity of the cells on current draw and how they recover. In the "storage" use, when you have fairly low cycling (50-150 a year) and low currents, quite much time pass before a mismanufactured B grade cell dies - people rarerly, in this type of use, get to the numbers of cycles and currents the cells are supposed to survive/last - the mismanufactured B grade cells are seen to be fit for purpose of energy storage (especially DIY). Different situation is with electric vehicles - where cycling can be frequent (people driving cars as part of work) and where also stress on the batteries is much higher - high currents going in and out of the cells in the frequent cycles.

The big problem with mismanufactured cells is that there is no one reason why the cells fail pass tests. They simply are not meeting expectation of a final product and are considered waste. The waste is bought by resellers like Docan (who are liers), selected and sold to us as a "A grade" cells. Only after such malpractice manufacturers see damage these resellers make to them and start marking cells - like EVE did with the "B" mark. Hope this marking by manufacturer will be a standard, so it will be harder for Docan and others scam us.

Like this video, because it shows how different the 4, "B grade" cells can be - one of them nicely keeps voltage despite high current draw while the other barely hanging on... You simply do not now what you get and one cell can cause lots of pain in your system. If you are a sole DIY and can manage failure of system - which most of DIYers can in their personal use then you'll likely live. If you are building system for someone or take on yourself risk of guarantee or need a solution you want make and forget about, then use of B cells is a risk to your activity.

before using , believing or using anything touched by skf, i would do a little forum search...

they are not know for being anywhere ethical, pleasant or well versed in testing
This series was made as a response to a forum members show and tell of their product

 

[Theo74]

The market of LifePO4 cells is overloaded and chaotic at the moment, so there is a chance that some 'cowboys' in the battery market want to use this situation for their own profit. Al lot of Chinese middle men presenting their self as manufacturer or EVE preferred supplier, only selling A quality.

On top of (EVE) grade A of grade B cells, is see more Chinese 'suppliers' use the term "grade A-" (A minus). This is explained as grade A cells which are stored for a longer time, and there fore can not be sold as grade A cells. Often with the added explanation that those cells have no QR code.

EVE does not sell any cell without QR code, regardless their grade. And only grade A or grade B, with a B in the QR code then. grade A- is a hoax.

 

[jimjoe]

before using , believing or using anything touched by skf, i would do a little forum search...

they are not know for being anywhere ethical, pleasant or well versed in testing
This series was made as a response to a forum members show and tell of their product

I have no opinion about SKF. The video they made is quite good in that it shows different physical behaviour of different cells in a set. What they SFK presented is quite similar to the following method of measuring health of a LiFePo4 cells - https://www.sciencedirect.com/science/article/pii/S0026271418305687 (If you look for a credible material on the subject)

 

[apctjb]

For what its worth (not much) I tested some of B cells I recently purchased. In terms of capacity I got what I paid for. Time will tell regarding cycles.

Capacity Test; Charge to 3.65; discharge 40A CC to 2.5V (25% sample; 4 cells out of 16 tested)

	Ahrs	Whrs
Cell 1	285.8	922.31
Cell 2	279.5	899.88
Cell 3	284.2	914.94
Cell 4	281.1	907.55

Voltage Slump; 40A-2 minutes. (50% sample; 8 cells out of 16 tested)

	Cell 1	Cell 2	Cell 3	Cell 4	Cell 5	Cell 6	Cell 7	Cell 8
Total Sag (V)	0.059	0.065	0.059	0.058	0.067	0.058	0.058	0.058
1 sec Sag (V)	0.021	0.025	0.021	0.021	0.024	0.021	0.021	0.02
1 Sec mV/A	0.525	0.625	0.525	0.525	0.6	0.525	0.525	0.5

 

[Alkaline]

For what its worth (not much) I tested some of B cells I recently purchased. In terms of capacity I got what I paid for. Time will tell regarding cycles.

Capacity Test; Charge to 3.65; discharge 40A CC to 2.5V (25% sample; 4 cells out of 16 tested)

	Ahrs	Whrs
Cell 1	285.8	922.31
Cell 2	279.5	899.88
Cell 3	284.2	914.94
Cell 4	281.1	907.55

Voltage Slump; 40A-2 minutes. (50% sample; 8 cells out of 16 tested)

	Cell 1	Cell 2	Cell 3	Cell 4	Cell 5	Cell 6	Cell 7	Cell 8
Total Sag (V)	0.059	0.065	0.059	0.058	0.067	0.058	0.058	0.058
1 sec Sag (V)	0.021	0.025	0.021	0.021	0.024	0.021	0.021	0.02
1 Sec mV/A	0.525	0.625	0.525	0.525	0.6	0.525	0.525	0.5

These actually look very good you got a good deal I would say.

 

[perryfranz]

like Docan (who are liers)

those are hard words to say, did you had some issue with them? Just curiosity because I have to place an order for 8 EVE280 from EU and I tried Docan and Dongguan Lightning... so I'm quite interested on this and reading this is quite shocking after tons of good review of them here.

 

[jimjoe]

those are hard words to say, did you had some issue with them? Just curiosity because I have to place an order for 8 EVE280 from EU and I tried Docan and Dongguan Lightning... so I'm quite interested on this and reading this is quite shocking after tons of good review of them here.

Yes, unfortunately. In March, I made a purchase of 16 grade "A" cells, these cells were to come from EVE and be the famous now LF280K-280Ah. Before I made decision to buy, I asked many questions. I received pristine report of capacity test, showing cells with excellent parameters - all tested cells got about 290 Ah, 0.15mOhm internal resistance etc. (like a grade A, never or once/two times cycled you could expect). I got a picture of perfectly aligned cells that do not have distances between (my shipment). Everything excellent - like a grade A cells should have. When shipment finally arrived... cells were swollen with 5+ mm distance between them - no way to replicate presented picture of cells I received from Docan's representative. None of received cells had internal resistance that was on the report - all higher (but within specification of EVE LF280K range (so ok-ish)). The test report I was presented was from summer 2021 but the cells I received were manufactured in December 2021/January 2022 - no way the report was about the batch I received. In short, I was lied by Docan and received worse grade product, like many of us - I did not anticipate buy. If I did not ask questions and was answered in accordance to advertisement, clearly being shown that the cells I am buying are A grade cells - I could not say I was lied by Docan. To me it is a bunch of scumbags and I do not want have business with them. Honesty is key in business, especially when there's no warranty or the warranty is not possible to execute (cost of return to China may be close or exceed cost of cells).

Only today we know what was the situation with "grade A" LF280K-280Ah cells from EVE . It is known now that only EVE was selling grade A cells , for 2.5 times higher price than Docan and other sellers. The cells that were failing grade A certification, were sold to the other sellers that were re-selling the cells as grade A cells. Obviously, EVE in the situation was loosing face with poor quality, "grade A", cells flooding markets so just in the middle of the year started print "B" on QR code, on the second grade cells. Now the same cells are available on the market, in the price Docan was selling them in March, but have explicitly printed "B" on QR code - as they should have.

My personal experience with Docan is awful - in that sense that they are liers. You'll have a good connection, customer service, responsiveness but you will be presented reality of your purchase that won't exist. I also read good about Docan and was keen pay more to buy with them - that was mistake I won't make again (to me Docan is not worth making business with).

If you'll decide buy with Docan, ask for QR codes of the EVE280 cells. If they won't have B on them but you can decode them and see they were manufactured somewhere in December 2021/January 2022 (not sure about earlier/later manufacturing dates) - likely you'll get grade B cells from the pack I got, which weren't yet marked as B by EVE - EVE started marking the B somewhere at the end of spring this year.


Recenty, I saw Gobel Power describing little of this on their webpage with EVE LF280K cells -> https://www.gobelpower.com/eve-32v-280ah-rechargeable-lifepo4-battery-cell_p6.html . They also present how the "B" is printed on QR code by EVE now.

 

[apctjb]

The whole Grade A & B doesn't make much sense from a marketing perspective. So much better if EVE would create different SKU's /models depending on test results. Those suitable for EV are labeled as such with the test standard they meet, those suitable for storage with a different label and different standard. A lot less drama and customers can choose the price/test standard that meets their requirements.

Just because a cell does not pass the EV standard does not mean it is not suitable for a different application and certainly much better to have the product have a useful life than go to a landfill.

In the PV industry we started doing this decades ago. If a cell did not pass its flash test for one standard, it was binned accordingly and sold for a different (lower) standard. That's why you see modules from the same manufacturer with the same dimensions available as different models; for example 350W, 325W, 300W, 275W. They are not using different cells, just the rejects from the highest standard. I don't hear people call those cells manufacturing defects, yet they failed to meet the most rigorous test standard.