Original EVE LF280 cells?

[TouchHarder]

Hello Everyone

About 6 months ago I decided to build a camper van for which I ordered some Lifepo4 cells from China. Those finally arrived after a whopping 100 days of travel time. Due to the way the seller handled that "minor shipping time overrun" and his general behavior after the cells were paid for, I have my doubts that the cells are what he advertised them for. Can one of you guys tell me if these are genuine EVE LF280ah cells or just EVE clones?




I was able to scan the QR code, but it only shows the letters and numbers which are printed around the QR code...

I couldn't test them properly jet, due to a lack of equipment. I simply didn't ordered a DC power supply or battery tester because after 75 days I figured that the cells wouldn't arrive at all.

 

[TouchHarder]

What also comes to mind is, that they were advertised as brand spanking new.
But there QR codes are all over the place, from 93A to 8C1...

 

[TouchHarder]

Noone who knows?

 

[Gazoo]

Noone who knows?

As far as I know there are no clones of large cells. It would be too costly to copycat these and I am not sure the Chinese would allow it. The Chinese do copy themselves and sell clones of many things including smaller batteries, like 18650's. And in some cases they even admit the cloned item is a clone.

What you have are EVE cells, they are not clones.

But there QR codes are all over the place, from 93A to 8C1

But they are authentic QR codes and 93A to 8C1 are date codes. If you search the forum you can find out what they might mean. Possibly some were manufactured in 2018 and 2019. I will attach a spec sheet and if you scroll down towards the bottom you will see the explanation of the codes.

What also comes to mind is, that they were advertised as brand spanking new.

They might be new old stock cells. I wouldn't worry about it. Very few suppliers are selling new Grade-A cells even though they advertise them as new. As long as the cells don't have any physical damage and the screws go in perpendicular to the cells they should be ok.

Who did you order from? And what are the voltages of the cells now?

You have several options to capacity test. But the cells should be parallel top balanced and there are several options for that as well.

 

[TouchHarder]

Thank you very much, this was helpful and a little reassuring.

I ordered 12 cells, and they are all at 3,29v.... But they were in transit for 100 days, so I feel like that is okay.
For top balancing I ordered a Gophert CPS-3010II and was planing to parallel the cells up 4 at a time. Then just pump a constant 10 amps in them until the are at 3,6v. (I know it will take a while)

After that I got a daily smart BMS 250a and wanted to hook it up to one of those for capacity tests.

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[Gazoo]

I ordered 12 cells, and they are all at 3,29v.... But they were in transit for 100 days, so I feel like that is okay.

Yeah that is good.

For top balancing I ordered a Gophert CPS-3010II and was planing to parallel the cells up 4 at a time. Then just pump a constant 10 amps in them until the are at 3,6v. (I know it will take a while)

Or you could connect the BMS and the cells in series and they will charge much faster, then parallel top balance. Also look at the voltages of the cells after resting for an hour or so. Some recommend letting them rest for 24 hours. My cells were all at 3.5+ volts after sitting tor a couple of days. This tells us self discharge is not a concern.

After that I got a daily smart BMS 250a and wanted to hook it up to one of those for capacity tests.

I didn't invest in a capacity tester. I tested using an inverter. I figured if one of my cells looked troubling, then I would buy a capacity tester.

My 8S pack tested at 272ah's. Considering the cells all had a good appearance, and the price I paid, I am not complaining. Remember the lowest capacity cell will determine the capacity of your bank.

 

[GSXR1000]

12vell are you doing a 12v- 840ah battery?

 

[TouchHarder]

No I'm planning on a regular 12v 280ah. I ordered more for other uses.

 

[TouchHarder]

Maby installing the bms first is the way to go. It would charge a lot faster at 12v, thats for sure.

 

[GSXR1000]

Maby installing the bms first is the way to go. It would charge a lot faster at 12v, thats for sure.

check my build

Thread 'Just ordered Lifepo4 prismatic cell 3.2V 280Ah lithium lifepo4' https://diysolarforum.com/threads/j...smatic-cell-3-2v-280ah-lithium-lifepo4.14955/

 

[TouchHarder]

@Gazoo
He I put 4 of them in the 4S config and started charging with 14v 8a, but after only 800wh into the charging i have one cells acting up.
3 cells stay within 0.04V of each other but one cell already has a 0.2V difference. (I turned the chargin of for now)
Cell1: 3.383V
Cell2: 3.346V
Cell3: 3.341V
Cell4: 3.526V
They all started at 3.29V.
When I turn the charging of the all fall back to:
Cell1: 3.322V
Cell2: 3.322V
Cell3: 3.322V
Cell4: 3.322V
Cell4 was falling back quicker then the other cells aswell.
Is that normal or do I have a bad cell?

 

[Bud Martin]

Are those readouts from the BMS?
All connections are solid?
Try swapping the cell location and see if the problem will follow or not.

 

[TouchHarder]

Yes i got the readings from the smart bms app.
The connectons are only handtight because the torque wrenche is still in the mail. I tought at 8a it wouldnt matter that much...
I guess swapping the cells is a good idea. I will try that.
Thanks

 

[Bud Martin]

You will be surprise what 8A can do with poor connection.

 

[TouchHarder]

But wouldn't it be the other way around then? One cell having a bad connection getting less power?
Even if cell 4 is the one conneted to the dc power supply directly (main positiv) and the other 3 cells are connected badly, cell 4 shouldnt take voltage this fast, right?

 

[TouchHarder]

Nevermind. I had a "not so tight" connection that caused the error. (A pice of wire isolation was wedged between a washer and a busbar.)

 

[GSXR1000]

did you top balance? sounds like no... these cells can contain different charge (AHs) at the same voltage especially in the middle band.

 

[TouchHarder]

I'm on it right now.
But they arrived at 25% SOC. If I put them in parallel now it will take 21 hours per cell... I have 12 cells. There is no way in hell I'm top balancing for 10 and a half days. So I put them in serial (as suggested by Gazoo) to charge them up to 3,55V and then start the top balancing in parallel. I know that they hover around 3.3V for 80% of the charge cycle, but I configured the BMS so that it stops charging at 3.55V or at a max cell difference of 0.2V.
If a cell arrived fuller than others the BMS should cancel the serial charging before it overcharges a cell. I will go over that bridge if it happens.

I just got a little scared at the beginning because of the high voltage difference in such a short time period, but that was due to a faulty connection which is fixed now.
They are charging with a 0.005V difference at max for about 3h now. Most of the time the voltage is exactly the same.
I turned down the charging to 6a tough. The stock cables of the charger got a little toasty at 10a. So until I made some beefier charging leads its charging at 6a, which is still double the speed than 10a in parallel.

 

[Zwy]

But wouldn't it be the other way around then? One cell having a bad connection getting less power?
Even if cell 4 is the one conneted to the dc power supply directly (main positiv) and the other 3 cells are connected badly, cell 4 shouldnt take voltage this fast, right?

Until you top balance, the voltage seen means nothing.

Charge until one cell hits 3.65V (make certain your BMS is set to stop charging when a cell hits 3.65V), break the pack down and do the top balance.

The minor changes one might see during initial charging simply means one cell might have more electrons stored than others when it was shipped. LFP curve is flat, voltage is a poor indicator of charge until you hit the knee areas.

 

[TouchHarder]

That is what it looks like for now. I know it looks horrible, because it is
But at 6a nothing other then these tiny charging leads should have a chance of getting warm.
The stuff for the compression frame is still in the mail, aswell as the cables for the new charging leads and the torque wrenche.