Just bought 16 Eve LF280K A grade; update on degradation after 15 months

[Zwy]

No idea, but Andy set his to stop at 5A

Maybe he should have used cell compression. He doesn't use compression, it might have a huge effect on aging and reduced capacity.

If he really wants a valid test he should have had a pack with compression to compare.

If the manufacturer specifies compression and a user doesn't use compression, then the user should probably expect accelerated decline in capacity.

 

[Alkaline]

tests done on lf304 don't need any of these fany perfect temp and compression, they are pass just fine and exceed the rated spec by 3-5%.

Not sure why the 280K does less but I doubt any codling will change the rating of the cell.

 

[S Davis]

tests done on lf304 don't need any of these fany perfect temp and compression, they are pass just fine and exceed the rated spec by 3-5%.

Not sure why the 280K does less but I doubt any codling will change the rating of the cell.

I don’t know where you get that info the EVE304 are not even rated without compression. And temperature affects capacity, so it is important to take that into consideration when testing.

 

[cajocars]

I just got the EVE test reports from Fogstar; this is the second cell that I tested (the one that gave 279.1 Ah); apparently EVE tested 292Ah; all the cells in this sheet have between 290 and 294Ah

 

[Alkaline]

I don’t know where you get that info the EVE304 are not even rated without compression. And temperature affects capacity, so it is important to take that into consideration when testing.

Pretty sure cajo tested this inside and as long as it was 10 degree C or above it will not make any difference. Discharge rate makes bigger difference at .2 C you will not have a noticable difference at all.

If anything you could replace the aligator clips with lugs. I saw a 2AH difference when I did this on my tests. I have he same charger/tester cajo has so I know what I'm talking about.

There are some other users that have tested the 304 using the ZKE, no issues testing to 315AH on a 304 rated cell.

Basically anyone with a 280K is going to be about 10AH lower than the manufacturer spread sheet, this is been shown repeatedly form multiple users and mutltiple vendors. All the same. Hovering between 276-280 regardless of what the test report says.

 

[Ron-ski]

The data from Eve shows mine as between 290 and 294, with an average of 291.8AH

I have the same tester as well, but didn't want to test mine until I have some compression sorted, but I may not even bother.

 

[cajocars]

Has anyone tried the internal resistance test?
The manual says to set the current to 0.5C or 1C, so I guess I can only set it to 40A max; it also say to fully charge the battery first, is this really necessary?





P.S. testing a 3rd cell tonight

 

[Alkaline]

The data from Eve shows mine as between 290 and 294, with an average of 291.8AH

I have the same tester as well, but didn't want to test mine until I have some compression sorted, but I may not even bother.

yah the compression thing.. don't end up like this guy: https://diysolarforum.com/threads/p...what-went-wrong-and-have-i-broken-them.51573/

 

[Ron-ski]

yah the compression thing.. don't end up like this guy: https://diysolarforum.com/threads/p...what-went-wrong-and-have-i-broken-them.51573/

I shall do my best to avoid that, the whole compression thing is a minefield, ideally what I'd like to do is basically what Seplos did in the 280AH version. I've got 10mm aluminium end plates, 3mm foam for between the plates and all cells. just need to work out what the measurement should be between the end plates.

 

[Zwy]

I don’t know where you get that info the EVE304 are not even rated without compression. And temperature affects capacity, so it is important to take that into consideration when testing.

Last page says it all regarding battery temp and compression. Good info, thanks.

 

[Zwy]

Pretty sure cajo tested this inside and as long as it was 10 degree C or above it will not make any difference.

It will make a difference, if you want to test to rated capacity to a spec specified by the manufacturer, then you have to use the same specs in the setup. Omitting procedures leads to not only erroneous data but also where conclusions upon that data is tainted.

Must be another "trust the science thing" but the "science" is whatever one decides it is. Sorry, but if you want to present a case where cell capacity isn't what the manufacturer states it is, then you have to check all the boxes, not just the ones you want to choose.

Andy's test is faulted, if he wanted to make a real comparison to stated capacity and aging, then he needed a control that is according to manufacturer specifications- that is, the correct compression over the last 4 years and testing at the correct temp. Anything else is really tainted data.

Discharge rate makes bigger difference at .2 C you will not have a noticable difference at all.

If anything you could replace the aligator clips with lugs. I saw a 2AH difference when I did this on my tests. I have he same charger/tester cajo has so I know what I'm talking about.

There are some other users that have tested the 304 using the ZKE, no issues testing to 315AH on a 304 rated cell.

Basically anyone with a 280K is going to be about 10AH lower than the manufacturer spread sheet, this is been shown repeatedly form multiple users and mutltiple vendors. All the same. Hovering between 276-280 regardless of what the test report says.

 

[Zwy]

I shall do my best to avoid that, the whole compression thing is a minefield, ideally what I'd like to do is basically what Seplos did in the 280AH version. I've got 10mm aluminium end plates, 3mm foam for between the plates and all cells. just need to work out what the measurement should be between the end plates.

I've posted quite a few times how I have done it, you will need the compression data on the foam you use. My preferred foam is Poron.

 

[Alkaline]

It will make a difference, if you want to test to rated capacity to a spec specified by the manufacturer, then you have to use the same specs in the setup. Omitting procedures leads to not only erroneous data but also where conclusions upon that data is tainted.

Must be another "trust the science thing" but the "science" is whatever one decides it is. Sorry, but if you want to present a case where cell capacity isn't what the manufacturer states it is, then you have to check all the boxes, not just the ones you want to choose.

Andy's test is faulted, if he wanted to make a real comparison to stated capacity and aging, then he needed a control that is according to manufacturer specifications- that is, the correct compression over the last 4 years and testing at the correct temp. Anything else is really tainted data.

Ok smarty pants, show us how its done do your tests and make a video explaining process. If you don't then you can keep shouting form the peanut gallery.

 

[S Davis]

Ok smarty pants, show us how its done do your tests and make a video explaining process. If you don't then you can keep shouting form the peanut gallery.

Well that seems like what you’re doing, how can you bitch about not getting the capacity that the manufacturer states without following their test specifications and procedure? That is why we have spec sheets to give us a base line to evaluate performance, sounds like you need to read some.

 

[Alkaline]

Because the same manufacture makes the 304 and it meets capacity without all the fluff and puff so did the 280N. You go around claiming we are all doing unacceptable testing yet we have no issue with the 304 and 280N passing our flawed tests.

But the 280K should get an exemption?

Get a clue, even the grade B CATL 280 Docan is selling blows the 280K out of the water and for far less.

NOT ACCEPTABLE!

 

[Ron-ski]

I've posted quite a few times how I have done it, you will need the compression data on the foam you use. My preferred foam is Poron.

Thanks, I've found this thread, not got the time to read as need to get to work, if there is a better thread please let me know.

This is the foam I have https://www.efoam.co.uk/zotefoam-plastazote.php don't know how it compares to Poron.

 

[cajocars]

		EVE capacity	EVE shipping voltage	EVE internal resistance	my capacity measurement (mAh)	my capacity measurement (Wh)
1​	04QCB76844701JC680002208	293996.9​	3.2953​	0.148​	280500​	907.38​
2​	04QCB76844701JC680001875	294316.8​	3.2957​	0.147​
3​	04QCB76844701JC680001715	293291.4​	3.2952​	0.159​
4​	04QCB76844701JC680004155	294956.3​	3.2953​	0.158​	279100​	902.65​
5​	04QCB76834001JC670000899	291631.3​	3.2941​	0.151​
6​	04QCB76844601JC670000860	292695.6​	3.2948​	0.151​
7​	04QCB76844701JC680001471	293500.9​	3.2951​	0.150​
8​	04QCB76834001JC670000644	290837​	3.2952​	0.157​
9​	04QCB76844701JC680004818	292677.8​	3.2952​	0.151​	testing
10​	04QCB76844701JC680001673	293996.9​	3.2953​	0.148​
11​	04QCB76844701JC680002498	294956.3​	3.2953​	0.158​
12​	04QCB76844601JC670005833	293937.4​	3.2958​	0.148​
13​	04QCB76844601JC660002731	292393.8​	3.2949​	0.152​
14​	04QCB76844701JC680003444	294956.3​	3.2953​	0.158​
15​	04QCB76844701JC680000264	292868.1​	3.2953​	0.152​
16​	04QCB76844701JC680002057	294316.8​	3.2957​	0.147​

I might have time to test them all, it depends on when the BMS and inverter arrive.
I'll definetely test the highest and lowest internal resistance ones, altough the ones I already tested appear to be the second highest and second lowest internal resistance (according to EVE sheet); also highest and lowest according to EVE might be a good choice.

It would be interesting to see if there's any correlation between the IR values and my measured capacity or between my measured capacity and EVE's
As you've probably guessed, I've nothing better to do

 

[billt1827]

These are my test results.
The first 15 are Fogstar grade B cells. They have a random selection of manufacturing dates and quite a wide capacity variation. I only tested them from 3.4V to 3V as that's the way they will be used.
The second 12 were bought via AliBab and all have the same manufacturing date and a very consistent capacity. These were tested from 3.65V to 2.8V to compare with the claimed capacity.

As far as I'm concerned the are both perfectly good results especially considering the cost of the cells

 

[cajocars]

These are my test results.
The first 15 are Fogstar grade B cells. They have a random selection of manufacturing dates and quite a wide capacity variation. I only tested them from 3.4V to 3V as that's the way they will be used.
The second 12 were bought via AliBab and all have the same manufacturing date and a very consistent capacity. These were tested from 3.65V to 2.8V to compare with the claimed capacity.

As far as I'm concerned the are both perfectly good results especially considering the cost of the cells

View attachment 124927

Your Fogstar B cells are impressive considering you only discharged them from 3.4V to 3V; my A grade Fogstar were discharged from 3.65V to 2.5V and I got the same results as your Alibaba ones.

I just had a look at my data and integrated from 3.65V to 3V (to see what I would have got if I stopped at 3V)
My A grade cell would only give me 270Ah (876Wh), which is similar to your worst B grade; and that's starting from 3.65, not 3.4!

 

[Alkaline]

These are my test results.
The first 15 are Fogstar grade B cells. They have a random selection of manufacturing dates and quite a wide capacity variation. I only tested them from 3.4V to 3V as that's the way they will be used.
The second 12 were bought via AliBab and all have the same manufacturing date and a very consistent capacity. These were tested from 3.65V to 2.8V to compare with the claimed capacity.

As far as I'm concerned the are both perfectly good results especially considering the cost of the cells

View attachment 124927

Do you have the WH readings for your grade B fogstar cells?