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EVE 280AH cell has low voltage after storage.

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SunPowered

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I started building an 8s 24v diy the other day from 8 Eve 280ah cells. I bought these brand new from china 1.5 years ago but unfortunately they have been sitting in storage since I got them and ignored. Voltages are below:

EVE 280AH
2/27/2023
3.291
3.291
3.290
3.290
3.287
3.283
3.264
2.125
After paralleling all 8, voltage was 3.277V. After 13 hours 3.285V

QUESTION 1: Am I correct to assume the 2.125v cell is trash and I shouldn’t waste my time with it any further?
QUESTION 2: Is there a reputable source stateside to order a replacement from? Looks like 18650batterystore.com has them for $149 plus $14 shipping ups ground.

TIA
 
SunPowered said:
I started building an 8s 24v diy the other day from 8 Eve 280ah cells. I bought these brand new from china 1.5 years ago but unfortunately they have been sitting in storage since I got them and ignored. Voltages are below:

EVE 280AH
2/27/2023
3.291
3.291
3.290
3.290
3.287
3.283
3.264
2.125
After paralleling all 8, voltage was 3.277V. After 13 hours 3.285V

QUESTION 1: Am I correct to assume the 2.125v cell is trash and I shouldn’t waste my time with it any further?
QUESTION 2: Is there a reputable source stateside to order a replacement from? Looks like 18650batterystore.com has them for $149 plus $14 shipping ups ground.

TIA
Click to expand...
Charge all of them in a top balance. Either parallel charge them all to 3.65V or install a BMS with cells in series and charge until a cell hits 3.65V, break it down, put back in parallel and finish the top balance. Put cells back in series with the BMS and draw a load thru a shunt until one cell hits 2.5V and the BMS cuts off discharge. See what the capacity of the pack is, then determine if indeed you have a cell that has failed.

I wouldn't put any faith in a static voltage measurement to determine cell health.
 
Zwy said:
Charge all of them in a top balance. Either parallel charge them all to 3.65V or install a BMS with cells in series and charge until a cell hits 3.65V, break it down, put back in parallel and finish the top balance. Put cells back in series with the BMS and draw a load thru a shunt until one cell hits 2.5V and the BMS cuts off discharge. See what the capacity of the pack is, then determine if indeed you have a cell that has failed.

I wouldn't put any faith in a static voltage measurement to determine cell health.
Click to expand...
Ok that’s encouraging that at least there’s a chance the low voltage cell may be ok. I’ll proceed with your advice. It will be interesting to see if the suspect cell can hang with the others under load after top balancing. Thanks
 
Parallel charging will take about a week or so. I guess you might not be in a hurry as they have been sitting. Use a good power supply.
 
SunPowered said:
I started building an 8s 24v diy the other day from 8 Eve 280ah cells. I bought these brand new from china 1.5 years ago but unfortunately they have been sitting in storage since I got them and ignored. Voltages are below:

EVE 280AH
2/27/2023
3.291
3.291
3.290
3.290
3.287
3.283
3.264
2.125
After paralleling all 8, voltage was 3.277V. After 13 hours 3.285V

QUESTION 1: Am I correct to assume the 2.125v cell is trash and I shouldn’t waste my time with it any further?
QUESTION 2: Is there a reputable source stateside to order a replacement from? Looks like 18650batterystore.com has them for $149 plus $14 shipping ups ground.

TIA
Click to expand...

2.125 = replace the cell, or deal with problems, not worth the hassle. Once these go below 2.5 you basically ruined them.

Also don't mix and match 280N cells with 280K cells, if you have the ones with drilled holes they are 280N. Post picture of our cell. Try to find someone that has an old 280N in good condition they can sell you.
 
SunPowered said:
I started building an 8s 24v diy the other day from 8 Eve 280ah cells. I bought these brand new from china 1.5 years ago but unfortunately they have been sitting in storage since I got them and ignored. Voltages are below:

EVE 280AH
2/27/2023
3.291
3.291
3.290
3.290
3.287
3.283
3.264
2.125
After paralleling all 8, voltage was 3.277V. After 13 hours 3.285V

QUESTION 1: Am I correct to assume the 2.125v cell is trash and I shouldn’t waste my time with it any further?
QUESTION 2: Is there a reputable source stateside to order a replacement from? Looks like 18650batterystore.com has them for $149 plus $14 shipping ups ground.

TIA
Click to expand...
I forgot to ask where you were measuring voltage? If on the stud, you will not get a true reading. Voltage needs to be measured at the base.
 
Zwy said:
I forgot to ask where you were measuring voltage? If on the stud, you will not get a true reading. Voltage needs to be measured at the base.
Click to expand...
I measured directly on cell terminals. Thanks
 
Alkaline said:
2.125 = replace the cell, or deal with problems, not worth the hassle. Once these go below 2.5 you basically ruined them.

Also don't mix and match 280N cells with 280K cells, if you have the ones with drilled holes they are 280N. Post picture of our cell. Try to find someone that has an old 280N in good condition they can sell you.
Click to expand...
They have tapped holes, photo below.
Regarding the 2.125V, your response is what I expected. However I already started with Zwy’s suggestion. I have the cells in 8s 24v battery with overkill bms charging with a cheap bench power supply cc limited to 5A. See screenshot below. Cell number 1 is the suspect cell and it is no longer the lowest. But I know the proof will be in the discharge. Regardless I’m still inclined to continue the charge and then top balance in parallel then rebuild into 8s and test discharge. May be wasting my time but won’t hurt, and I could use the experience and may learn something. Thanks for your input!
5A73CFD4-7CD4-459A-BB60-C96FB816949B.jpeg
 

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To follow up on this thread, the suspect cell, and the battery as a whole, is doing fine so far. I charged, top balanced, charged, and then did a capacity test discharge over about 3.5 days. According to the Overkill BMS the battery provided the full 280AH, although barely (so the entire 100% capacity) when the battery voltage reached 24.16V, still above my cutoff of 24V. A DROK meter tracked within 1% capacity with the Overkill on both charge and discharge, so I have some confidence in the numbers, although I realize neither would be extremely accurate, but the fact that they track is good enough for this rough test. The battery charged back to 280AH. I currently have the battery in service at my remote cabin.

FYI the weakest cell appears to be cell #2 which initially had a stored cell voltage of 3.264V. (I connected them up in series for the 24V battery in order of stored voltage measurements, the lowest = cell #1). That cell, #2, has the highest voltage when charging, and the lowest voltage when discharging, which I think indicates it has the highest internal resistance. However it is still acceptable. The original "suspect" cell (#1) that initially had a stored cell voltage of 2.125V is doing great. (Yes I am 100% positive I did not mix them up - I labelled them with a sharpie from the beginning.)

If I find any anomalies as I get more cycles I'll report them. Bottom line for now: don't jump to conclusions about low cell voltage on a stored cell.
 
Last edited:
Alkaline said:
2.125 = replace the cell, or deal with problems, not worth the hassle. Once these go below 2.5 you basically ruined them.

Also don't mix and match 280N cells with 280K cells, if you have the ones with drilled holes they are 280N. Post picture of our cell. Try to find someone that has an old 280N in good condition they can sell you.
Click to expand...
After our long sparring back and forth on the 280k cells not being any good and I was very happy with my results and thought they were a good cell I now just realized their 280n cells not k I guess that’s why mine meet capacity no problem sorry my bad ? I will defer to your input on k cells in the future due to the fact I have no k cells once again my bad?
 
You really don't know, the 280N always ranked WAAAYYYY higher, in fact go watch this video:


These REPT cells even grade B are cheaper than the 280K and basically bulldoze over the 280k, both are rated for 6000 cycles. Grade B or A better than the 280K any day of the week.

Now tell me, and $80.00 dollar grade B REPT cell has no problem meeting capacity...

EVE also makes a 304, no issues at all with meeting capacity only the 280K has these problems.
 
He doesn't have any EVE 280K or EVE 280N in the video. You can't compare the REPT cells in his video to a EVE cell because he didn't test any EVE cells. What was the temp he tested at? I never saw any mention of temp.

My 280N all tested 280.5Ah minimum. The 280K tested within 1% of the 280N, lowest was 278Ah.

The EVE 304Ah tested 310Ah minimum. The EVE 304Ah are newer than the any other cell I have by at least 9 months.

All of my cells were tested at 68F. That is less than the specs, higher temps will raise the Ah results.
 
The cells test within 1% of 280Ah at 68F. The Ah would be higher at the spec'd temp. Was I sold something that wasn't what it was stated? I don't see it that way, I was sold what it was stated it was. The majority of cells test over 278Ah at 68F.

You missed the point, you have tried numerous times to tell people they are not getting what they paid for but that is not correct.

I can also tell you the 304Ah may test over the rated capacity, however, under real usage the cells tend to not hold balance as well and also sag more under load compared to the EVE 280K. Granted, these were B cells but you want to compare apples, oranges and a hamburger.
 
MisterSandals said:
I would charge that one cell VERY gently, like an amp or two, until it gets to 3.0V. Then bring up to match others.
Make sure you label your cells so you can keep track of issues like this.
Click to expand...
I very much agree with this approach. The battery should be treated gently, which will help the cycle life of the battery. If the voltage of the Lifepo4 battery is adjusted to the extreme, it will not be conducive to the cycle life of the battery.
 
Zwy said:
The cells test within 1% of 280Ah at 68F. The Ah would be higher at the spec'd temp. Was I sold something that wasn't what it was stated? I don't see it that way, I was sold what it was stated it was. The majority of cells test over 278Ah at 68F.

You missed the point, you have tried numerous times to tell people they are not getting what they paid for but that is not correct.

I can also tell you the 304Ah may test over the rated capacity, however, under real usage the cells tend to not hold balance as well and also sag more under load compared to the EVE 280K. Granted, these were B cells but you want to compare apples, oranges and a hamburger.
Click to expand...
cant say i observe the same behavior in my lf304's.
seem to behave exactly as my calb plastic encased 150ah cells did for years
 
houseofancients said:
cant say i observe the same behavior in my lf304's.
seem to behave exactly as my calb plastic encased 150ah cells did for years
Click to expand...
I use a Batrium BMS and can see the cell voltage sag pretty easily when charged full and discharge occurs. You won't see it as much of course once below 3.4V until you get to the lower knee. Same with charging, 304's tend to run more than the 280's from the data I have.

Don't get me wrong, these cells are perfectly fine for use in a solar system. It's just the little things that you see from different cells. I still recommend the 304's over the 280K given the price point and test results I have. I just don't care for someone saying the 280K were somehow sold dishonestly when the lowest cells I tested all came within 1% of the stated capacity. I received what was advertised. Does the same person measure the beer in each bottle before they drink it to see if it is outside a 1% window of the stated volume?

Over time, the 280K might actually have longer cell life, better balance and less voltage sag compared to the 304's. Or the 304's might indicate the cells are far superior to the 280N or 280K.
 
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