Capacity - factory specs vs the supply we are accessing

I figured I had posted quite relevantly on another thread but perhaps not.

I have an invoice for 64 EVE cells I have yet to send payment on and my question below is what has me on hold.
I see now a declaration on Docan's site that the LF280K capacity spec for the cells they sell is 260-280Ah:
"The capacity of 280K produced in 2022 is 260-280Ah"
But I see EVE factory specs as 280Ah as the minimum capacity.
I also see a number of happy customers reporting 280+ in testing what they receive.
I'd be disappointed to see a large delivery of less than 280Ah cells arriving at my door.
Is anybody getting these cells from the most reputable distributors identified here at less than factory spec capacities?

Jaxonwood said:

I figured I had posted quite relevantly on another thread but perhaps not.

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Huh?

Jaxonwood said:

I have an invoice for 64 EVE cells I have yet to send payment on and my question below is what has me on hold.

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First, if you NEED 64 cells, buy 66-68. Shit happens. You don't want to be held up because cells were damaged or some other issue, and it won't hurt to have a few spares down the road.

Jaxonwood said:

I see now a declaration on Docan's site that the LF280K capacity spec for the cells they sell is 260-280Ah:
"The capacity of 280K produced in 2022 is 260-280Ah"
But I see EVE factory specs as 280Ah as the minimum capacity.

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Because you're not getting true grade A cells for these prices. They aren't available on the gray market serviced by these sellers. These are cells that fall short of spec for some reason but tend to be reasonably high quality. All Grade A cells meet ALL aspects of the datasheet.

Jaxonwood said:

I also see a number of happy customers reporting 280+ in testing what they receive.

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And lots testing < 280Ah, but not by a lot.

Jaxonwood said:

I'd be disappointed to see a large delivery of less than 280Ah cells arriving at my door.

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Then you need to double your budget, get your wallet out and source cells from an Eve authorized distributor that sells true Grade A cells.

Jaxonwood said:

Is anybody getting these cells from the most reputable distributors identified here at less than factory spec capacities?

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Yes. Lots.

The 9 Eve cells I received from Amy Wan in Jan, 2021 tested 263-278Ah. I was very happy with the value.

sunshine_eggo said:

Huh?



First, if you NEED 64 cells, buy 66-68. Shit happens. You don't want to be held up because cells were damaged or some other issue, and it won't hurt to have a few spares down the road.



Because you're not getting true grade A cells for these prices. They aren't available on the gray market serviced by these sellers. These are cells that fall short of spec for some reason but tend to be reasonably high quality. All Grade A cells meet ALL aspects of the datasheet.



And lots testing < 280Ah, but not by a lot.



Then you need to double your budget, get your wallet out and source cells from an Eve authorized distributor that sells true Grade A cells.



Yes. Lots.

The 9 Eve cells I received from Amy Wan in Jan, 2021 tested 263-278Ah. I was very happy with the value.

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Ok, well, then it seems it is what it is then with the 260-280Ah statement Docan has made. I suppose I am mainly reflecting off some YouTube tests, one sticks in my head of all of the many cells yielding over 280. I'll adjust my expectations if need be, but I still want what they were having.

Jaxonwood said:

Ok, well, then it seems it is what it is then with the 260-280Ah statement Docan has made. I suppose I am mainly reflecting off some YouTube tests, one sticks in my head of all of the many cells yielding over 280. I'll adjust my expectations if need be, but I still want what they were having.

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let you in on a secret.... they are cells pulled from a bus or a prime mover. You cannot by International law ship used batteries... they are considered hazardous waste and to prevent rich countries from dumping their shit into poor countries there are international laws which prevent the shipping of anything that is considered Hazwaste.

Sooo... the Chinese sellers seeing a demand for cheap sells, take cells that are pulled from service and then clean them up and sell them as "new" cells. basically lying on the export certs.... thats why they tells you they only are good from 260-280. the original brand new from the factory cells will hit their nameplate rating. you nor I can afford them (honest to god brand new LiFePo4) for a DIY project. You are looking at second life cells just like everyone ends up buying. after that it depends upon the buyer you are buying from. my calb 180's tend for the first 32 I bought tend to hit 175... the second batch of 16 only hit 170 or so.... the last set are hitting 165... IE the guy I buy from got his hand on a bunch of cells grouped them into like health ranges and sold them until he ran out of cells... I bet people buying from him now are lucky to get 150 out of the same identical "LOOKING" cells.

FFS we have videos of "factories" rewrapping the aluminum case cells in the blue film... do a short search on this forum, or youtube. they can affoed to waste two or three bucks on acetone to remove the adhesive and re-wrap as they are probably getting paid to dispose of said batteries.

Delanaway said:

Hello everybody, i have been searching a lot for a good seller to buy 16 lifepo4 280ah, 302ah, 310ah and so on, i have read many threads. everyone follow everyone, and i decided to follow my instinct. of course i was looking for a better price too, so i find "Shenzhen good Leader" on alibaba, my first contact was with Shelly Qu, what a woman. Very professional, and i know what i say. she advised me from the beginning about the cells and the bms, very frankly, despite my freely question packet, she was not annoyed at all. after many chats i ordered x16 LF280K and a BMS 8S 300A for my 24V system. She is very straight, honest and personally i love that. I got my cells in very good condition to france 2 months and few days, grade A as she promised me, balanced, flawless. I'm happy. I received them in france but i have to bring them to another country where i live in a farm off grid. So, to all who want to buy battery or BMS or such things, go ahead, don't be afraid. Not all the chinese are the same, like all over the world. a lot of fake and scam in the usa, ue, every where. Don't follow always those who are payed in a way or another to bring you to some sellers who try to monopolize the market (and that is normal when it comes from a supplier, i understand ). There are many others honest people out there. I have nothing to get here. I'm free. I will make a video when i get to my place. until there, I hope i brought some help here. ( and this reply, i will put it every where ? )

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There's no need to make 5 identical posts in multiple threads. You are cross-posting. Stop. It feels very spammy and has been reported.

sunshine_eggo said:

The 9 Eve cells I received from Amy Wan in Jan, 2021 tested 263-278Ah. I was very happy with the value.

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263 =

94% rated capacity for $122 delivered. Met IR and SD spec loosing only 676 mAh after sitting for 158 days. Cells top balance maintained within 0.15%.

Calling it a turd is only applicable if one expected them to meet 280Ah. I never did. I'm not stupid.

Did you perform a WH test on your cells?

Alkaline said:

Did you perform a WH test on your cells?

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The test logged it, but I didn't pay attention to it. 20A test at 3.2V w/8 awg had a .1 to .15V drop, so Wh is less reliable than Ah in this case.

Alkaline said:

Did you perform a WH test on your cells?

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Checked the log. 263Ah tested 794Wh, but that's measured based on the voltage drop value, not the OCV. Observed voltage drop was about 4% based on average drop (.125V) and nominal cell voltage (3.2V).

If anyone is testing Wh using loaded voltage, they will always fail to meet Wh even if Ah are met.

Then your cell is only 248 AH @ 3.2 if your test was 794 WH a 280K cell is 896WH so 88.6% of original capacity

All of my Luyuan matched & batched genuine cells don't meet or barley meet AH of 280 (usually 278-280) but they always are over 900WH. I first thought I got jipped even with Amy wan, but now I can firmly say this AH Is a scam reading the real reading is WH.

Look at the test, I finally broke down and got a ZKE40 tester and just finished a test.

278 AH but 901WH

why is the csv file not attaching??

Ok I had to zip it see the attached csv and screenshot.

901.44 WH but only 278.4 AH

Alkaline said:

Then your cell is only 248 AH @ 3.2 if your test was 794 WH a 280K cell is 896WH so 88.6% of original capacity

All of my Luyuan matched & batched genuine cells don't meet or barley meet AH of 280 (usually 278-280) but they always are over 900WH. I first thought I got jipped even with Amy wan, but now I can firmly say this AH Is a scam reading the real reading is WH.

Look at the test, I finally broke down and got a ZKE40 tester and just finished a test.

278 AH but 901WH

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No. I don't think you understand testing. The cell is 263Ah as measured. It delivered 20A for 13.15 hours. That is 263Ah. Ah is independent of voltage - ALWAYS.

Wh introduces additional variables - IR of the cell and resistance of the test equipment. Wh is the open circuit voltage times the current integrated over time. Because my equipment used the loaded voltage instead of the OCV to compute Wh, it is not a reliable measure of capacity. I applied the 0.125V average drop to the 24,000 data points to estimate OCV, and my Wh yield is 860. This is approximate based on the 0.1V difference I observed at the start of the test vs. the .15V difference near the end of the test.

I'm guessing you missed this:


Ultimately, you're splitting hairs... with cheap chinese equipment. Have you calibrated or at least correlated measurements with a known reliable standard, or are you assuming your tester is 100% accurate? It's impossible to make claims of meeting/not meeting specs unless you have some confidence in the accuracy of the test equipment. I do. I've correlated my three dozen testers to known sources and literally tested the capacity of > 10,000 batteries.

Have you checked the accuracy rating of your unit? They are comical. They actually conflict with each other. Best case, your Wh values are accurate to ±1%, which wipes out the 278Ah vs. 901Wh difference.

Lastly, the cells should meet ALL specs. They rarely do unless obtained through official distributors.

Well I"m starting a thread about this, I spent over 389 on amazon for this and its going back if the ZKE is busted, that or something else is going on.

Here is the thread, anyone else that has a ZKE40 can comment: https://diysolarforum.com/threads/what-is-going-on-here-just-got-zke-40.49076/

Measured capacity is a poor indicator of cell condition. Voltage drop under load is better.

If i had one test i could do on a LiFePO4 cell of unknown quality i’d compare the voltage drop under a 1C load over time.

So watt-hour would show that along with average voltage.

Alkaline said:

So watt-hour would show that along with average voltage.

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You need to discharge at a high C rate to show up cell degradation. The Wh will be significantly different at the maximum C rate vs C/10, and this gap widens as the cell ages.

40 Amps is what I can do and already I have spent too much buying testers, together 500.00 almost. However, I do find results interesting that Marched & batched cells with reports have no problem with WH rating but not necessarily meeting AH.

I should have basen test result ready by tomorrow, I'm discconected the WIFI on my laptop this time so windows does not F me over and ruin the test with an update and restart like last time.

Alkaline said:

40 Amps is what I can do and already I have spent too much buying testers, together 500.00 almost. However, I do find results interesting that Marched & batched cells with reports have no problem with WH rating but not necessarily meeting AH.

I should have basen test result ready by tomorrow, I'm discconected the WIFI on my laptop this time so windows does not F me over and ruin the test with an update and restart like last time.

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ummm just whom are you selling for?