How to tell if EVE cells are A or B, and does it really matter?

[apctjb]

Below is the QR code for EVE 280K cell I recently received. Curious to hear from folks that have figured out the code if this is an A grade or B grade cell and when manufactured.

The deeper question, for solar storage application with relatively low C rates and maintaining SOC between 30-90% does A vs B grade really matter (other than cost). My gut tells me that on a $/kwhr basis you might be money ahead with B cells , but have not done the analysis to verify that ....yet.

 

[Bud Martin]

Did you try LiFePO4 QR Code Scanner?
See link in my post #802

Our NEW GO-TO LiFePO4 vendor...09.20.21

Bought 16 of the LF280K cells plus their JBD 7S-20S-200A BMS through Jenny from the Houston warehouse. http://www.powerwholesale.net/us-stock-lf280k-eve-280ah-new-version32v-lifepo4-prismatic-cells-with-free-busbar-p-3888.html#show...

diysolarforum.com

or:

LiFePO4 Cells (LFP)

+ some Sodium cells further down… LiFePO4 battery cells (LFP-cells) are now commonly used in solar storage projects as well as in electric vehicles. These cells have a lower voltage of 3.2V t…

off-grid-garage.com

 

[apctjb]

Did you try QR code scanner?
See link in my post #802

No I had not seen this before. Downloading the app as I type and will give it a try. Many thanks!

 

[apctjb]

The scanning app worked! (took a few tries).

The cell was manufactured 12/25/2021 and lists the capacity of 280ah. Not sure if that is measured or simply nameplate.

But it doesn't tell me if the cell is A grade (which I understand is a very tight standard for EV application) or something else. I have EVE recently started marking B grade cells with B on the QR code but have not seen an example of this.

 

[Bud Martin]

I doubt that they are grade 'A' unless you buy directly from EVE at premium price or from Amy Wan of Luyuan, she is supposed to have direct supply with EVE.

 

[apctjb]

I doubt that they are grade 'A' unless you buy directly from EVE at premium price

These came from Jenny at DOCAN, which like Amy has quite a following on this forum. But I don't know if they are A or B, hence the question. What would rate as a premium price for EVE280K in the current market?

 

[Bud Martin]

You can get quote from EVE on Alibaba, I.E: $217 a piece + shipping

Eve Eu Stock Lf280k Lifepo4 Battery Rechargeable Power Energy Lfp Prismatic Solar System Batteries 3.2v Lifepo4 280ah Battery - Buy Lifepo4 Cell eve Lifepo4 Battery prismatic Battery Product on Alibaba.com

Eve Eu Stock Lf280k Lifepo4 Battery Rechargeable Power Energy Lfp Prismatic Solar System Batteries 3.2v Lifepo4 280ah Battery - Buy Lifepo4 Cell eve Lifepo4 Battery prismatic Battery Product on Alibaba.com

www.alibaba.com

 

[Bud Martin]

I believe this place sells Grade A EVE cells since it has EVE terminals on them, I would think EVE will not put on their terminals on failed QC cells.
Some members here had bought some.

EVE LF280K V3 Grade A Cells - 3.2V LiFePO4 280Ah Battery

Brand new Grade A EVE LF280K LiFePO4 cells with 280Ah capacity. 10+ years design life, 6,000 cycles. Get unmatched power and performance for your energy storage needs.

www.18650batterystore.com

 

[apctjb]

You can get quote from EVE on Alibaba, I.E: $217 a piece + shipping

If that price is indicative of Grade A then despite the assurances I was given I must have B... and if that is the premium one must pay for Grade A then my gut feeling that B's offer a better $/kwhr lifetime cost is even stronger...Thanks

 

[rhino]

It has been stated that EVE now stamps all rejected cells with a B on the QR code to make it obvious if they aren't grade A. They only started doing that sometime earlier this year so yours is likely manufactured before they started doing that. 280Ah mentioned from the QR code app is purely the nominal value and nothing to do with the actual Ah capacity. You'd have to test that yourself to find out that value. This really isn't much different than solar panel manufacturers who have slightly different watts for the same exact panel sizes because some of them simply test lower and therefore they charge less.

 

[hankcurt]

When dealing with vendors, it is important to realize that Grade 'A' or Grade 'B' has no standard definition.

The manufacturers sell batteries that make the grade for vehicle use, which does have government mandated standards even in China. The ones that don't meet the requirements of the EV specifications wind up sold to resellers who put them on the secondary market. In the secondary market, batteries that are clean and not swollen or dented and show no signs of previous use are often referred to as Grade 'A'. This does not mean they are EV grade batteries. It is also not an assurance of the usable capacity of the battery, as the resellers don't test every cell in each batch they get.

I heard about the plan to stamp a 'B' on the QR code of EVE cells quite a while back. I bought some cells on the secondary market that were manufactured at the start of March 2022, and they still did not have the 'B' on them.

 

[740GLE]

I think Aprilish was the reported cut over for B QR codes.

 

[apctjb]

This really isn't much different than solar panel manufacturers who have slightly different watts for the same exact panel sizes because some of them simply test lower and therefore they charge less.

Yes, solar panels are flash tested and binned according to output at the end of the assembly line. For example 350W, 325W, 300W, all of the same dimensions. You pay for the watts you get and all the modules are legit, labeled according to tested output, and sold through normal distribution channels.

But it sounds not quite the same with EVE batteries. Batteries are tested (is capacity of each battery really tested...hard to imagine) and those that pass are legit Grade A sold to EV manufacturers and perhaps a few distributors and everything else is sold via different channels/resellers and buyer beware. Makes sense to me that EVE would want to protect its brand reputation by better labeling and marking B grade cells.

 

[BradCagle]

Batteries are tested (is capacity of each battery really tested...hard to imagine)

Yes, they test the capacity.

They also must store the cells for quite some time (I think a month) to fully test the self discharge rate.

 

[apctjb]

Yes, they test the capacity.

Interesting! Each cell stores ~1kwhr of energy times hundreds of thousands of cells produced that Gigawatt hours of energy just for testing. Hope they capture that some way...

 

[740GLE]

You mean like discharge full cells into dead cells?

 

[apctjb]

You mean like discharge full cells into dead cells?

Yes, is there another way to accurately test the actual capacity of the cell other than running it through a discharge cycle?

 

[Steve_S]

EVE like every other company does a Production Run Test at the end. They have massive banks of testing gear that each cell gets hooked up to. They cycle the cells and take 3 reading points and measure the mOhms at those points, which must fall into a very specific range (it's tight).

Something to NOTE that Far Too Many are confused about...
LFP "Allowable" Voltage Range is from 2.500-3.650. This is the voltage range where the cells will suffer no harm / deterioration.
LFP "Working" Voltage Range is from 3.000-3.400 Volts per cell, this is where the AH comes from. The Nominal is 3.200 (50% SOC)
2.500-3.290 is the cliff fall on the curve, 3.450-3.650 is the Cliff climb on the curve.

You can charge a cell to 3.650 to the point where it takes 1A only (fully saturated) disconnect everything and it will self-discharge and within an hour it will be at 3.500 +/- and in another hour it'll be close to or on 3.400

The 10% to 90% Wives Tale as it is pushed, is to prevent the foolish people from using the "Cliff Fall / Climb" areas, thinking that is useable energy space.

 

[apctjb]

Something to NOTE that Far Too Many are confused about...
LFP "Allowable" Voltage Range is from 2.500-3.650. This is the voltage range where the cells will suffer no harm / deterioration.
LFP "Working" Voltage Range is from 3.000-3.400 Volts per cell, this is where the AH comes from. The Nominal is 3.200 (50% SOC)
2.500-3.290 is the cliff fall on the curve, 3.450-3.650 is the Cliff climb on the curve.

Thanks, as always your post provide valuable insights and much appreciated.

 

[Theo74]

The scanning app worked! (took a few tries).

The cell was manufactured 12/25/2021 and lists the capacity of 280ah. Not sure if that is measured or simply nameplate.

But it doesn't tell me if the cell is A grade (which I understand is a very tight standard for EV application) or something else. I have EVE recently started marking B grade cells with B on the QR code but have not seen an example of this.

Like this: