Are we all getting GRADE B cells??

740GLE

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I know I’m not buying “the best”, I’m buying “good enough” for my needs. Just like my Busch lite and honey toasted os.

My cells 8 230ah in 12v set up are for a 3 season camp running lighting and a small diaphragm pump, hardly system critical.
 
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C-Koyote

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Is it a runner if it doesn’t increase dramatically until after >3.5v?
I watched "Andy's Offgrid Garage" experiments on charging LFP to understand the characteristics.
My answer to your question would be "no".
You may have found your answer already but Andy's video's made me understand to charge to 3.45 is enough.
Above that 3.5 you go up in voltage very quickly yes but from 3.45V on you are near max capacity already anyway.
Unless you are using them in an RV or boat and need them to charge quickly before leaving, there is little need to charge above 3.45 which is over 96% if I remember correctly. Charging to higher voltage only saves time and causes more stress on the cell(s). So for offgrid stationairy with a fair amount of Wh comming in 3.45 should be OK and above 3.5 goes fast to 3.65 and there is little capacity left to reach full SOC.

EDIT: https://diysolarforum.com/resources/general-lifepo4-lfp-voltage-to-soc-charts-tables-12-24-48v.109/
 
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Alkaline

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I think that eve spreadsheet is what signifies grade A, so I have seen sunfunkits and luyuan have this and both are priced in the 200-250 range / cell as of 2022.

Now weather or not it is worth paying is a different story.

Who else has eve spreadsheets?
 

Rossman

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I think people are in denial here, that eve spreadsheet is what signifies grade A, so I have seen sunfunkits and luyuan have this and both are priced in the 200-250 range / cell as of 2022.

Now weather or not it is worth paying is a different story.

Who else has eve spreadsheets?

I dont think anyone is in denial here, people have been quite clear they have made a value judgement and don't feel their use case (solar) demands EV grade cells. I also think it depends on how someone defines "Grade A". Let's be real: that is not a real thing, it's completely made up, and it doesn't share a common definition in peoples minds (ie you might think of Grade A as EV grade but I might think of Grade A as new/unused cells).

The only real grading that appears to exist is, if you get the spreadsheet from EVE that indicates that the cells are EV-grade and meet the EV battery standard that sunfunkits refer to in the OP video.

It would perhaps serve the conversation well if we all used terms that were well defined. Given that people generally associate "Grade A" products as "new and unused", I would perhaps propose:

EV Grade (f.ex Luyuan Grade A/matched) - comes with cell test spreadsheets from EVE/meets EV spec
Grade A (f.ex Luyuan Grade A- / Docan) - new, unused cells, which haven't passed the EV grading, but are still more than ok for solar uses
Grade B - used cells / swollen b/s / garbage

Food for thought!
 

robby

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I dont think anyone is in denial here, people have been quite clear they have made a value judgement and don't feel their use case (solar) demands EV grade cells. I also think it depends on how someone defines "Grade A". Let's be real: that is not a real thing, it's completely made up, and it doesn't share a common definition in peoples minds (ie you might think of Grade A as EV grade but I might think of Grade A as new/unused cells).

The only real grading that appears to exist is, if you get the spreadsheet from EVE that indicates that the cells are EV-grade and meet the EV battery standard that sunfunkits refer to in the OP video.

It would perhaps serve the conversation well if we all used terms that were well defined. Given that people generally associate "Grade A" products as "new and unused", I would perhaps propose:

EV Grade (f.ex Luyuan Grade A/matched) - comes with cell test spreadsheets from EVE/meets EV spec
Grade A (f.ex Luyuan Grade A- / Docan) - new, unused cells, which haven't passed the EV grading, but are still more than ok for solar uses
Grade B - used cells / swollen b/s / garbage

Food for thought!
I think your dead wrong. Based on the discussions I have read on the forum my take is that the majority of people that bought cheaply priced "Grade A" cells or 48V Packs assume that they got them for a low price because the seller was a modest guy or an efficient guy who is selling on a low margin. The price was not low because it has defective cells or cannot pass a set of tests but because the seller is a fair guy while those other guys like Sympliphy, Fortress, Blue and BYD are all trying to make an outrageous profit selling the same quality cells for a huge profit.

BTW Tier 1 Grade A cells is a real thing with exact metrics for qualifying.
 

Alkaline

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Ok so Real Grade A EV Grade sellers so far:

Official Eve Store on Alibaba
Luyuan
Sun Fun Kits

who else has the cells with manufacturer spreadsheet, we should make a list, in fact a tired seller list would be good for all people on the forum.
 

Rossman

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Ok so Real Grade A EV Grade sellers so far:

Official Eve Store on Alibaba
Luyuan
Sun Fun Kits

who else has the cells with manufacturer spreadsheet, we should make a list, in fact a tired seller list would be good for all people on the forum.
I've been emailing back and forth with Seplos lately (about their cases for 280Ah cells), they say if you buy cells from them, they come with test reports, and have a 10 year warranty. I have never bought cells from them though, sooo, I don't really know.
 

Rossman

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From Seplos

I mean those are great videos but they don't talk about the EV standard for cells, which is I guess what I was trying to fit into the hierarchy of cell grading with my post. I guess by Seplos' definition, Grade A = EV grade.

Also, I guess they confirm that Docan cells are not "Grade A" as the second video says the battery should perform at 1C rates (Docan says only use their cells at 0.1C rates)
 

robby

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I mean those are great videos but they don't talk about the EV standard for cells, which is I guess what I was trying to fit into the hierarchy of cell grading with my post. I guess by Seplos' definition, Grade A = EV grade.

 

Alkaline

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I've been emailing back and forth with Seplos lately (about their cases for 280Ah cells), they say if you buy cells from them, they come with test reports, and have a 10 year warranty. I have never bought cells from them though, sooo, I don't really know.


that is good ask them for a test report on a few cells lets see what they look like. But make sure it has each listed individually not just random sample report with partial serial numbers.
 

Alkaline

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Well looks like the JIG is up, EVE is starting to mark all cells that are not Grade A as grade B from the factory.

No more grade A- bs.
 

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toms

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It will be interesting if this is legit to see who has been swimming with no pants on. If a vendor suddenly doesn’t have A grade cells or has a significant price increase it will tell a story.

Of course you can always find plenty of A+++ cells on Alibaba for cheap!
 

SparkyJJO

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I mean those are great videos but they don't talk about the EV standard for cells, which is I guess what I was trying to fit into the hierarchy of cell grading with my post. I guess by Seplos' definition, Grade A = EV grade.

Also, I guess they confirm that Docan cells are not "Grade A" as the second video says the battery should perform at 1C rates (Docan says only use their cells at 0.1C rates)
The ones I bought said 1C on their webpage (max).
 

740GLE

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Well looks like the JIG is up, EVE is starting to mark all cells that are not Grade A as grade B from the factory.

No more grade A- bs.

Spill the beans, what vendor was selling those? We’re they listed as grade A? Or is that just some random internet picture?
 

Rossman

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The ones I bought said 1C on their webpage (max).
Yeah, the webpage shows the specifications for that battery, if it's passed the EV grade/certification. That doesn't tell the full story though.

If you do a capacity test you will find you can only get full capacity at low C rates, and if you ask Docan (as people here have) they will tell you to capacity test at only 0.1C (and at that rate, you will get the rated capacity).
 

Alkaline

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Spill the beans, what vendor was selling those? We’re they listed as grade A? Or is that just some random internet picture?

Luyuan sent me this image and she told me that vendors are now either going to raise prices or make fake QR codes like they have been doing with used CATL cells.
 

740GLE

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Wonder how long it’ll take other EVE sellers will have real QR codes or fake ones.
 

lfpinside

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One wonders though... say you make XAh cells. Statistically, σ% of your cells turn out to have σ% less capacity. You could make them X+σ (+Y% for safety) and sell them for X. The result would be... all your cells meet or exceed capacity expectations.

Marketing-wise, it would well pay for the added expense, wouldn't it?
But then, manufacturers do (or tend to) not think that way. Marketing people do.
Maybe if manufacturers listened a bit more to marketing people, instead of always having to be the other way around... :·)
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Cells are not money, more does not mean better.

The most important thing in a battery is the consistency of many cells.

If a battery has 4 cells, 3 cells have 285Ah, and 1 cell has 290Ah, all other parameters are the same. Then which cell is better?

Compare cell by cell, you may think 290Ah cell is better.

But, cells don't work alone, you have to put them in series or parallel.

In the above battery, the 290Ah cell is the bad one, this cell makes the battery unbalanced.

You can only judge a cell (without defects) as good or bad when it is in a group.

What is Grade A+, Grade A Grade A-, or Grade B? No agreed definition at all. Ambiguous definition causes meaningless debate.

Cells are not clothes, they are not made in bulk and go to a warehouse and sold to different customers.

Cells are made on-demand. According to the CATL datasheet, when a downstream company put an order to CATL, they should tell CATL the project design and BMS parameters, CATL will make cells according to these parameters. Then cells are sorted according to a standard, some cells which do not meet standards will be left. The downstream company is not allowed to modify project design or BMS after cells are made, otherwise, CATL will not provide any warranty. These are "Grade A" cells if we insist to give cells a grade.

Then what about the cells left. Are they bad cells? The answer is Yes and No.

Some cells are indeed bad cells with defects, such as too high IR or self-discharging rate. These cells will not go to market usually.

Some cells are good cells, they just cannot be put into that big "Grade A" group according to that specific standard for that specific project. Sometimes because they are too good, such as capacity is too high. These are “grade A-” or “grade B” cells. They will be sold to the distributor in bulk. Manufacturers will not provide any warranty, this is why many CATL cells have scratched QR.
 
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