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Docan 8x EVE 280ah slightly swollen

I recently purchased 4x EVE LF280K cells from Docan (Jenny) with production dates in Dec 2021 - Jan 2022, and all cells were swollen upon delivery, a similar amount to jay_jay's cells.

I top balanced all cells to 3.65v and ran capacity tests to 2.5v at 23A, and unfortunately all cells failed the test.
The 3x cells with a Dec 2021 production date returned 270-271Ah.
The 1x cell with a Jan 2022 production date returned 277Ah.

I also ran a capacity test with the cells in a 4S configuration. I top balanced all cells to 3.65v and set the BMS low voltage protection to 2.5v, and the test stopped at 270Ah as one of the Dec 2021 production date cells triggered the low voltage protection. The cells had a voltage difference of 0.46v at the end of the test.

The capacity tester was tested prior to the test.

It seems there are a few of us that received swollen cells from Docan with similar production dates.

For those of us who received swollen cells from Docan, how is everyone getting on?
 
I have the same issue too, 2 of the cell's being particularly bad. I had made a box to put them in and ended up 1/4 inch short because of the swelling...teach me to measure the waist not the edge lol.
I am not fannying around with top/bottom charges and capacity test's etc unless Amy insists on it for replacement cells.
It is a disappointing turn of events but I fear it is an indication of the supply chain.
The 230's I got last year were as flat as a pancake.
 
Mine are slightly swollen too, got them 2 months ago but haven't had the time to do anything with them. Wasn't going to test then but think I might now ?
 
I wonder, are you folks adjusting for cell temperature when you do the capacity test? Cooler LiFePO4 cells have significantly lower capacity. It would take 0C or 32F to get close to a 10% capacity drop, but a cool battery might be a few percent low. Does putting a few cycles on the battery help? I sensed that it did on some 280 cells I had but I didn't do proper tests so can't say for sure. I also added some expansion constraint that might have affected capacity (again, not real testing).
 
I wonder, are you folks adjusting for cell temperature when you do the capacity test? Cooler LiFePO4 cells have significantly lower capacity. It would take 0C or 32F to get close to a 10% capacity drop, but a cool battery might be a few percent low.
Yep I made sure the cells were between 15-20°C for the whole duration of the tests.

Does putting a few cycles on the battery help? I sensed that it did on some 280 cells I had but I didn't do proper tests so can't say for sure. I also added some expansion constraint that might have affected capacity (again, not real testing).
I've completed 3 full cycles and the capacity test is the same between the first and the third cycle.
 
It won't be popular, but there is a lot of validity to the claim that watt hours is what you should be measuring for capacity.

Watt hours is a measure of current and voltage and accurately describes how much "work" a cell can do. Amp hours measures how many hours at what current without any measure of voltage that current is supplied at.

I don't have any of the newer model EVE 280 cells to test, but my understanding is they were changed to increase cycle life. I have no clue what they changed, but generally speaking if a cell hits the claimed number of watt hours it should be regarded as meeting specifications (even if amp hours measures low).

You will however need a tester that measures voltage as well as current, not just current. Voltage sense leads are required for accuracy when measuring watt hours.

Edit to add that EVE should really change the spec sheet to use watt hours rather than amp hours. It's confusing otherwise.
 
If they were sold as 270AH cells everybody would at least be getting exactly what they paid for :)
 
It won't be popular, but there is a lot of validity to the claim that watt hours is what you should be measuring for capacity.

Watt hours is a measure of current and voltage and accurately describes how much "work" a cell can do. Amp hours measures how many hours at what current without any measure of voltage that current is supplied at.

I don't have any of the newer model EVE 280 cells to test, but my understanding is they were changed to increase cycle life. I have no clue what they changed, but generally speaking if a cell hits the claimed number of watt hours it should be regarded as meeting specifications (even if amp hours measures low).

You will however need a tester that measures voltage as well as current, not just current. Voltage sense leads are required for accuracy when measuring watt hours.

Edit to add that EVE should really change the spec sheet to use watt hours rather than amp hours. It's confusing otherwise.
The older EVE LF280N are rated 3500 cycles @ 1c, the newer EVE LF280K are 6000 cycles @.5c. So lowering the discharge rate by one half for a little less than double the cycles.

This is under compression, the LF280N are 2500 cycles without compression and the LF280K are not rated without compression on the spec sheet.
 
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If they were sold as 270AH cells everybody would at least be getting exactly what they paid for :)
That's why I was pointing out that EVE should really change their spec sheet.
It is confusing to me, and I understand the difference between amp hours and watt hours, EVE certainly should as well.

I don't think changing the spec to use 0.5C was the only change they made to the cells, but I don't know.
 
That's why I was pointing out that EVE should really change their spec sheet.
It is confusing to me, and I understand the difference between amp hours and watt hours, EVE certainly should as well.

I don't think changing the spec to use 0.5C was the only change they made to the cells, but I don't know.
The cells are physically different. They are taller and the terminals are closer to the ends.
 
Yep I made sure the cells were between 15-20°C for the whole duration of the tests.


I've completed 3 full cycles and the capacity test is the same between the first and the third cycle.
I did this search (link below) and the first image shows capacity vs temperature. It's a bit difficult to use but was the only one I found in a quick check. I also found in other threads in this forum the suggestion that rated capacity of Eve cells is at 25C. It seems that at 15-20C a cell could easily show 270 or less. See also post #5 in the second link.


 
I bought 4 280k cells last week and they all swollen somewhat. Two are more than others. I fully discharged to see if swollen goes away but no, they are still swollen. For capacity test I got 269ah and 277ah the two I tested. I specifically asked Jenny Wu about if these have less than 280ah capacity as per their website and she says that’s not correct ??‍♂️
 

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If they were sold as 270AH cells everybody would at least be getting exactly what they paid for :)
Yes this would have been better, however, I have heard some people have 280K's with 295AH capacity? I have tried to find this thread but it was one of the very first 280K threads on this forum.
 
I bought 4 280k cells last week and they all swollen somewhat. Two are more than others. I fully discharged to see if swollen goes away but no, they are still swollen. For capacity test I got 269ah and 277ah the two I tested. I specifically asked Jenny Wu about if these have less than 280ah capacity as per their website and she says that’s not correct ??‍♂️

There is a rumor going around that EVE had a big 280K order get cancelled from some car / buss company and they had a lot of cells that they just off loaded on the DIY market even as Grade A that are failing capacity tests. I think the Gobel Power guy knows about this.
 
I bought 4 280k cells last week and they all swollen somewhat. Two are more than others. I fully discharged to see if swollen goes away but no, they are still swollen. For capacity test I got 269ah and 277ah the two I tested. I specifically asked Jenny Wu about if these have less than 280ah capacity as per their website and she says that’s not correct ??‍♂️
Sorry to hear. I've never tested my cells individually but the whole pack (top balanced) never delivered more than roughly 267ah. So more or less the same as your low cell. They're behaving nicely though, delta is consistently below 10mv and no runners on the top. So I would have been happy with 270ah advertised.
I hope you're still able to enjoy your cells, apart from the missing ah they're great.
 
Sorry to hear. I've never tested my cells individually but the whole pack (top balanced) never delivered more than roughly 267ah. So more or less the same as your low cell. They're behaving nicely though, delta is consistently below 10mv and no runners on the top. So I would have been happy with 270ah advertised.
I hope you're still able to enjoy your cells, apart from the missing ah they're great.
I am also seeing very balanced when in the middle of charging/discharging. Yes, they are really matched well I guess. In fact, I bought 5A active balancer from Amazon and most likely I won't use it :)

I am relatively new to battery building, but from my going through this forum in last couple weeks, and watching some Will's and Lithiumsolar video, I believe these are actually grade B cells. This amount of bulging, even when it's discharged completely, may cause internal sorting between layers and that can accelerate in the future, only time will tell. I think they should sell as grade B and/or at least notify us about the bulging.

Positive thing is the price was about same as getting cells from China (Basen offered little lower price for their US stocks though) and I didn't have to wait that long. Also for my few charge-discharge cycle, and stationary use (home power backup) I will probably be good.
 
That would be the flat part of the charge discharge curve so that is not diagnostic.
Right! Not having balance is actually a problem on charging to full and discharging to bottom as BMS stops when the first cell reaches the threshold... I forgot about that. I am going to charge it full and check the balance.
 
Has anyone bought the same B grade 280ah batteries from Luyuan? I chatted with Amy after noticing the spec sheets for the real A grade was the same as the B grade. She said the only difference was the self discharge rate. I then told her I needed to occasionally discharge 160ah 0.6C to meet the full load on my 8kW inverter. She spoke to her engineer who advised getting real grade A. We're all going for 280ah because they give the best bang for buck. They appear to be cheap for a reason. Any reports on the Luyuan $110 cells?
 
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