How to tell the difference between Grade A and Grade B cells.

mizermizer

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APPEARANCE: Each battery is produced with a QR code that allows the end-user (YOU) to get information about the battery and get assistance for
Using the QR code, how does one get manufacturer information about their battery? The cells I have are supposed to be EVE cells, and according to an EVE datasheet the QR code looks legit, but that's as far as I get.
 

ghostwriter66

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Thanks for your very informative post. The only thing I would like to add is not all suppliers are consistent in what they are selling. Some people have very mixed results who have ordered from the same supplier.
So I have found the suppliers that I have had the most issues with have also been the suppliers that I went with because they were the less expensive .... I have had them send me fake pictures and fake voltage readings etc etc ... And you're right ..I have had some that we great for 4 months or so then suddenly a bunch of crap shows up ...
 

ghostwriter66

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From LA -work in South Texas/New Mexico region
Using the QR code, how does one get manufacturer information about their battery? The cells I have are supposed to be EVE cells, and according to an EVE datasheet the QR code looks legit, but that's as far as I get.

The codes are typically two parts depending on the reader software being used ... the first contains proprietary information of the manufacturing of the cell (ie date, batch, location, time, etc) and the other is the QR code normally contains a Material Safety Data Sheet for HAZMAT chemicals required by International law when the battery is shipped air, land or sea. Ut is unlike tore QR codes that actually send you somewhere to see something.
 

mizermizer

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Joined
Apr 17, 2021
Messages
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Location
Southern California
The codes are typically two parts depending on the reader software being used ... the first contains proprietary information of the manufacturing of the cell (ie date, batch, location, time, etc) and the other is the QR code normally contains a Material Safety Data Sheet for HAZMAT chemicals required by International law when the battery is shipped air, land or sea. Ut is unlike tore QR codes that actually send you somewhere to see something.
Okay, appreciate the explanation. Was dreaming of some magic way to link to factory test data. Silly me, ha-ha.
 

Berseker

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The codes are typically two parts depending on the reader software being used ... the first contains proprietary information of the manufacturing of the cell (ie date, batch, location, time, etc) and the other is the QR code normally contains a Material Safety Data Sheet for HAZMAT chemicals required by International law when the battery is shipped air, land or sea. Ut is unlike tore QR codes that actually send you somewhere to see something.
so the REPT cells you bought, would you call them grade b?. cos mine even though looks new, have their qr codes scratched off covered by black tape and new qr code stuck on it. i observed late that the position of the qr codes are different from the OEM picture.
 

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tnt4him

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How to tell the difference between Grade A and Grade B cells. AND why you should always pay with CREDIT CARD.

Going to make this sort of in bullet form – otherwise this will go on for many of pages of rambling which this will probably be anyway..

Before I start …25C is 77F – the perfect temperature for LFP. Remember – LFP is a CHEMISTRY – strange things start happening as you get further away from 77F… Also keep in mind that honestly – no one really understands LFP. It’s a weird chemistry – it works remarkably well – but there is still allot of voo-doo in how it works. (Voo-doo being a technical word here – LOL)

But back to Battery ratings.

There are actually (5) five accepted commercial LFP ratings in China used by commercial companies.

GRADE A+
GRADE A-
GRADE B
GRADE C
SECOND-HAND


When dealing with the Anglos, the Chinese will often refer an A+ and A- as simply GRADE A and B/C as B.

I will not discuss Grade C or second hand – I am going to say that I have seen VERY little Grade C or Second Hand here on this forum. Both are obvious – leaking – dented (badly), warpage, and both will measure 3.2V but the moment u put a load on them they crash to below 1V instantly ...

And – although not a scientific observation, but as of 2021, you can typically tell your Grade B and below simply by their packaging. The ppl that are passing off Grade B for A’s and trying to separate you from your money most usually is not wanting to waste allot of the profit in doing professional secure packaging but instead just drop it in a cardboard box – add allot of tape – and hope you don’t open them until after the dispute phase is over.

NOW – this will probably be the most important thing to take away from this. There is absolutely NO standard between each company on how they rate batteries. We have purchased some critical 3.2V 280Ah LiFePO4 batteries used for medical stuff from company XYZ that was considered GRADE C by that company BUT turned out to be better than any GRADE A+ listed by any of the normal LFP Alibaba companies.

My ex-boyfriend has an Audi R8. He loved that car. If it was a battery he would give it a GRADE A+. I hated it – you literally had to fall into the car to get in. And you literally had to roll out to get out. I could barely see over the dashboard. And the seats were hard and uncomfortable. I would give it a B-.

So batteries, as in car ratings, is in the eye of the beholder, or manufacturer – so to speak.

That’s why DATASHEETS are VITAL. And not the datasheets the VENDOR supplies BUT the datasheet of the manufacturer. !!

(Beat a dead horse time) …BUT one of the things that kills me most is when ppl do NOT read the datasheet of the particular manufacturing company they are purchasing the batteries from. This is vital. You MUST have a datasheet to compare the results you are getting to what they said you should be getting.

The first thing I do is weigh each and every battery we receive. That right there tells me if its going to meet 90% of my expectations. Testing voltage rarely tells me anything. (Heck a dead 9V battery still reads 9V). The second thing I do is an IR test.

SO the best way to know if a cell is actually a Grade A all the way thru Second Hand is look at the manufacturers specifications and compare it to your results.

The (6) six key parameters that must be checked to determine the proper grading is:

Appearance, Size and Weight, Capacity, Internal Resistance, Self-Discharging Rate, and Capacity Recovery.


Every manufacturer will grade every battery coming off the line against these 6 parameters. Most manufacturing companies have this done by computers and an automated process. But any of these 6 factors can cause an GRADE A to go to C in a heartbeat. The issue for US is that these reputable companies will sell their GRADE C’s to a distributor as a GRADE C for pennies on the dollar, and the distributor turns around and sells the Grade C to someone as a GRADE A and hope you don’t test IR or Capacity Recovery or something before its too late to dispute. ALIBABA is VERY much against companies doing this and will support you in getting your money back for this.

APPEARANCE: Each battery is produced with a QR code that allows the end-user (YOU) to get information about the battery and get assistance for warranty and customer service. …. In China, Grade B cells do NOT have a warranty, so 100% of the manufacturers will scrape off the QR code before pushing them to a reseller as B-Grade. Sometimes the manufacturer will not scrape the QR code but simply put a new black insulating panel over it. Either way – missing, scratched, or covered with a black strip -- its a GRADE B cell (normally). If there is a QR code under the strip of black plastic – IT’S A GRADE B….

SIZE AND WEIGHT: So this one is a little tricky. Batteries will be different size and weights at different SOC and temperatures. You would need to ask the manufacturer what temperature and SOC they used in their testing so you have the same baseline to judge yours from. BUT if its bloated like a football or weighs like a feather – good signs its not Grade A - LOL. If the datasheet does give SOC and temperature at time of testing – and your battery does not meet the requirements within a range of error – then you’re probably looking at a B.

CAPACITY: Another pet peeve of mine. For LiFePO4 batteries – worldwide – the standard testing criteria is 25C with a charging and discharge of 1C. Testing any differently will get you different results then the data sheet because of temperature and charge / discharge variances. Different temperature deviation from 25C on LiFePO4 has a measurable difference on capacity … with that said – often times its minimal but the baseline testing worldwide is at 77F at a 1C charge and discharge.

INTERNAL RESISTANCE: This is an important one – making LFP batteries is complicated – it truly is. Some companies have this down to a science – others – not so much so. TONS of things can go wrong. TONS!! Going from materials to a finalized battery is a complicated 7 step process – and along that step a million things can go wrong – from bad materials to a microscopic tear in the combining sheet to the sheet tearing at the end, to etc etc. IR testing is a good way to see if everything is working on the inside. Again temperature and SOC from the datasheet is required. Most manufactures will suggest an AC internal resistance test but most of the end users like me utilize a DC IR reader. I’m lazy and its quicker and virtually just as accurate ….

SELF DISCHARGING RATE: So self-discharging is calculated by looking at the how fast the voltage is decreasing from its last SOC. As we all know with LFP – its pretty much a flat voltage line from 10-90%. So a battery at 100% state of charge will have a quicker discharge rate then one at 50%. So again – the data sheet is vital to see what the SOC was that they tested at. Now to be honest, YEAH there is a complicated formula they taught us in school and you need to let it sit for 90 days at 50% SOC in a room with a stable temp of 25C and this and that and to be honest – I normally skip testing this … But just in case you wonder anything UNDER 3.51% loss per month is considered GRADE A.

((SIDE NOTE)) – In China MOST GRADE A- cells being sold as GRADE A- is ONLY being sold as A- and not A+ because they have been sitting on a shelf for more than 6 months. Seriously – often times that’s ALL it takes for a manufacturer to drop it from a + to a -. And if a battery is going to last 13.5 to 15 years then 6 months to a year sitting on a warehouse shelf is nothing.

CAPACITY RECOVERY: This one is pretty straight forward – also known as Depth of Charge testing or – DOD. Just do a 100% charging and then 100% discharging and then 100% recharging. If the datasheet says that the Capacity Recovery rate is 100%, and you charge the battery to 100% after a discharge to 0%, then you are fine – if it charges to 98% (for example) then you have issues. Capacity test is how I find 99% of my bad batteries.

Finally a couple of notes from our real life measurements of 1000’s of various batteries….

Note 1.
Using a 280Ah battery as an example:
At 0C we get 85% capacity
At 25C we get 100% capacity
At 40C we get 80% capacity

Note 2.
For the last 1000 LFP batteries we have got in, 11% of my batteries did NOT match the datasheets requirements BUT they were good enough for what we needed. Some were off only by 2-3 Ahs … For example most of the 89% barely made the rated 280Ah and many of the 11% only got between 272-280%. Good enough for me BUT we did not get what we paid for. Being a bored angry Asian girl out in the middle of the West Texas desert, I normally tell Alibaba that if I paid $100 for a battery and its missing 5% of the Ah charge I paid for – then I want $5.00 back. Now multiply that by a 100 “bad” batteries and it comes to real money quickly … and often times I am successful in getting compensation. Most companies would rather pay you a few dollars back then deal with the pain of doing the right thing. AND if we all start complaining then they are less likely to pass B's off as A's.... Remember - they don't get paid UNTIL after the Assurance Deadline passes.

I think that’s about it.

sorry for the rambling.

Thx
Thank you so much for writing this! I am new to solar and stupidly bought several LiFepo4 batteries because i thought it was such a great deal. I bought from alibaba and found nothing
negative with a quick search on the Chinese plant. I plan to do all the test you prescribed when they get here. Multimeter and digital scale is all i have. Are there other tools essential that i should have for testing?
 

ken morgan

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May 11, 2021
Messages
390
Thank you so much for writing this! I am new to solar and stupidly bought several LiFepo4 batteries because i thought it was such a great deal. I bought from alibaba and found nothing
negative with a quick search on the Chinese plant. I plan to do all the test you prescribed when they get here. Multimeter and digital scale is all i have. Are there other tools essential that i should have for testing?
you will need a power supply to top balance with that is regulated and can be set at 3.65volts or lower. unless you feel like experimenting to see what actual capacity is then nothing else is needed.

read up on cell compression, as well as charging rates and profiles. this will help to prevent you from destroying that which you just bought.
 

Hedges

I See Electromagnetic Fields!
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Mar 28, 2020
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9,072
Individual cells, or batteries?

If individual cells (as Ken assumed), also a BMS for operating (or charging) the cells in series, of course.
 

elvis_asaftei

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Jul 5, 2021
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so the REPT cells you bought, would you call them grade b?. cos mine even though looks new, have their qr codes scratched off covered by black tape and new qr code stuck on it. i observed late that the position of the qr codes are different from the OEM picture.
it seems to be a common practice of scrapping all original QR codes ... and adding small new painted ones in the corner. I received also from CATL old cells that are rusted and being sold as brand new GRADE A cells by PWOD AliExpress Store Uff9b73a1722146ecac3041e69791cf6ex.jpg:

U04aa724abdf1426799cc1aa49d895885M.jpeg
 

elvis_asaftei

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The codes are typically two parts depending on the reader software being used ... the first contains proprietary information of the manufacturing of the cell (ie date, batch, location, time, etc) and the other is the QR code normally contains a Material Safety Data Sheet for HAZMAT chemicals required by International law when the battery is shipped air, land or sea. Ut is unlike tore QR codes that actually send you somewhere to see something.
what do you think about these ones ?


And also PWOD seller from China ?


 

elvis_asaftei

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Messages
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The codes are typically two parts depending on the reader software being used ... the first contains proprietary information of the manufacturing of the cell (ie date, batch, location, time, etc) and the other is the QR code normally contains a Material Safety Data Sheet for HAZMAT chemicals required by International law when the battery is shipped air, land or sea. Ut is unlike tore QR codes that actually send you somewhere to see something.

it seems that the fraud here went over the roof with this site and Interpol police has to do its job there :
 

ghostwriter66

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Location
From LA -work in South Texas/New Mexico region
I COMPLETELY understand your frustration and concern ...especially with the amount of money involved ...

so free advice --

when I get cells in I do the following ...

1. Look for obvious damage - and i don't mean scrapes or slight bulging but smashes and it looking pregnant
2. I weight each battery
3. I test the voltage but honestly - thats worthless - i just do it not to waste time later on
4. I then do an 100% capacity test. I plan on doing all the batteries BUT if I get the first 5% of the batteries randomly chosen all within the Ah capacity test I then just salute them all and move on .. I honestly don't have the time nor equipment to test all of these batteries ... and at 144 batteries neither do you ...

NOTE: I try to do my capacity tests at 1C because that's what the manufacturer rates their numbers at ... but if you can - just get as close as you can ... the lower the charge / discharge rate the more Ah you are going to squeeze o9ut which is not a true test of what they say ... anyway -- thats very minor

SOOOO you have done all the tests .. and DOCUMENTED each one with pictures and notes and things ...

I then contact Alibaba (or whoever) along wiht the seller and tell them that I paid for XXXX amount of capacity -- that I tested each and every battery (which i would if they did not measure up) .. show them the written proof - describe how you did it - show the pictures and then say .. I paid for 1000Ah and got 930Ah and you owe me compensation for 70 missing amp hours .. then divide the cost with the amount and tell them what that amount is...

And give your seller a deadline - but make it reasonable -- Chinese companies have to get like 20 ppls permission to return money of any sort ...

IF they do not play far AND Alibaba is not supportive then contact your Credit Card company and tell them the same thing you told the seller and Alibaba ... typically they will be on your side and will immediately jump in with both feet to help you ...

They will ask you for allot of proof like pictures of each battery - picture of the original POST / AD / WEBPAGE on the Internet (so you might want to get a screen save of that NOW - and they will confront the seller and Alibaba ...

Typically I have won several - most times ... recently MASTERCARD just told me to keep the batteries after getting tired of these idiots - froze the money to the Chinee company account -- and returned 7800 to our company credit card ...

And YES - on a totally different note -- I have got obviously used 280Ah batteries with rusted this or that or nor QR code or the plastic black stuff is peeling like an old banana ... YET still passed a capacity test with flying colours ...

BUT Yes it does suck - and I am sorry for you ... you want to make sure that you let Alibaba and the seller know ASAP that you are NOT pleased and that you will be testing each battery and getting back to the ASAP ... (YES I know that testing 144 batteries will take 6 months so just look for the worse ones and go from there) ... weighing is the quickest option - then looking for bloating and then rust ...

BUT Alibaba is really now starting to crack down on these guys selling B's for A's .. you just have to demonstrate to them that you have been ripped off ...

THE GOOD THING IS THAT the ppl that you are talking to at the company is probably going to be just as upset with their warehouse guys as you are ... long story - but i see this all the time ...
 
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Shawn Hayes

Learning Everyday
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Jan 11, 2021
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Location
South Carolina
it comes from how every other joke in the service involves being involuntarily sodomized in some fashion for example "you will walk funny for a week after the 1st sgt gets done with you" etc.
Reminds me of when I was telling my friend about the time I was attempting to be a paratrooper in the army.
When it was my time to jump out of the planes door, I was too scared to jump!! 😒
The drill Sargent told me to jump, son!! I told him there’s no way I could jump out of a perfectly good plane!
Drill Sargent said, son if you don’t jump out of this plane, I’m going to stuff my manhood when your sun don’t shine!!!! 😬
My friend said, well, did you JUMP???🤔
I said yeah, well, a little bit!!!! lol 😲
😂😂😂😂😂
 
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