There is no such thing as A-, A, B+ or whatever fantasy grade people want to come up with. Its either pass or fail. All the documentation and specs sheets you read about are for batteries that are EV Grade or Genuine A, all other so called grading is complete BS people just make up they have no standard to go by, it could be anything.
People just have this fake rolex mentality thinking ohh yeah, Its almost as good... It isn't.
This is what you have to expect, there is no guarantees when you buy reject sells, stop drinking the Kool-Aid the grade B seller is trying to give you, instead play the grade B strategy:
Buy 10-20% more than you need, pick the best from the lot you have and then just hope for the best, hopefully you will come out ahead vs buying grade A, but you have to be willing to put in the work. For most people they will end up saving more going this route than buying grade A cells and that is the dominant approach many people on this forum will take because the cost of grade A doesn't justify the benefit for off grid remote power.
On the flip side If you are just going to throw caution to the wind and just assume you just got a deal, then you are going to be end up looking like a sucker. Because without proper testing and sorting of grade B cells your pack is going to eventually cause issues with IR, not matching and balancing, Very very unlikely you hit the grade B jackpot where all of your cells just happen to be about the same.
Plenty of people have made decent grade B setups but they had to run cell tests, match the cells, themselves and sometimes even have to ditch a few because of issues.
If you don't have the time or resources to do this leg work, then don't' mess with grade B, either buy a retail ready to use battery or buy grade A cells.
That guy hates all lithium batteries IMO one of his biggest video is the lithium myth.Grade B vs Grade A
/start sarcasm
But the seller says they are Grade A on AliExpress
/end sarcasm
Where are you getting this info? I talked with Lampard Li and Amy Wan both said on the large cells the failure rate can be as high as 3%, the more watt/hour / lb the higher the failure rate is.I agree with this part "There is no such thing as A-, A, B+ or whatever fantasy grade people want to come up with. "
May not "It's either pass or fail."
What is pass or fail standards? If it is the EV factory's matching standard, then so-called 'grade B' cells are good cells, they just do not match the main group.
If fail standards is the cell has a quality issue, then EVE should have been bankrupted. This defective rate is too high. According to a report, CATL has a 0.1% defective rate, only 1000 cells have quality issues in 1 million cells.
It's nice to see the Forum members have stopped becoming stooges. When I bought up this topic 6 months ago in two other threads I was declared a Heretic and was literally beaten back to the point where I stopped posting to the threads.There is no such thing as A-, A, B+ or whatever fantasy grade people want to come up with. Its either pass or fail. All the documentation and specs sheets you read about are for batteries that are EV Grade or Genuine A, all other so called grading is complete BS people just make up they have no standard to go by, it could be anything.
People just have this fake rolex mentality thinking ohh yeah, Its almost as good... It isn't.
This is what you have to expect, there is no guarantees when you buy reject sells, stop drinking the Kool-Aid the grade B seller is trying to give you, instead play the grade B strategy:
It's nice to see the Forum members have stopped becoming stooges. When I bought up this topic 6 months ago in two other threads I was declared a Heretic and was literally beaten back to the point where I stopped posting to the threads.
I had Lengthy discussions at the time with Fortress Power, Sol-Ark and EcoDirect and all of them basically said the same thing to me.
If you see a 5KWh 48V Pack for half the Price of a Fortress or Simpliphi battery then it's Grade B PERIOD!!
Nobody wanted to hear that back then but luckily enough info has come out to prove it to be right
I have now come across another Interesting discovery in that not only do Grade B Packs take about 40% longer to charge than Grade A Packs but they also waste a lot more energy and in my case it got worst after just 6 months of owning the battery.
I am going to make a separate post and link it here:
I did not watch the second video yet but one of the things that he did not mention in the first video is that capacity is not the primary reason why cells get rejected. The number one reason is "Slitting" problems in the cells.Yes I agree but my conclusion was with my own experiences with Xuba and Basen.
Speaking off Andy just made 2 nice videos going into this:
&
I think people just need to come to the realization you get what you pay for.
Filing the edge of aluminum foil is not the simplest thing to do. They are talking about microscopic tears, and any sort of mechanical treatment would probably make it worse. I can see how a laser might be used to ball the edge slightly and make it less sharp, but then the thickness would change and build up over many layers.Well, that sounds a bit... I mean, if something as simple as rough edges causes serious defects, how difficult can it be to have the edges filed, as part of the same machine or the next one down the line? Not conceivably difficult or expensive, right? Certainly less expensive than rejected cells.
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very interesting insight on this mechanism of failure mode!I did not watch the second video yet but one of the things that he did not mention in the first video is that capacity is not the primary reason why cells get rejected. The number one reason is "Slitting" problems in the cells.
The machine that cuts the the strips of aluminum and copper will not always make a clean cut and the edges of these strips will have ragged sharp edges.
The strips are kept apart by separators that will get damaged if the edges are not smooth. Every charge and discharge cycle causes abrasion on the seperator due to the expansion and contraction involved. If the edge is not smooth it cuts into the seperator and causes arcing. This is why X-Rays are done on the finished cells to see if any slitting problems are present.
This slitting problem is what causes the batteries to develop a higher internal discharge rates which then leads to a rapid loss of useful capacity during a much shorter time period.
the pictures in the thread were helpful thanks for sharingAll of these prismatic cells on the market were made for Electric Vehicles, it should be clear by now if you look at there data sheet that was the intended purpose. They also are clearly set a testing standard to meet.
This Grade A vs Grade B debate no longer exist:
EVE identifies Grade B cells using new marking Method [Reposting from General]
Yesterday I got a new information from my supplier. I was supposed to order EVE LF230 (230Ah) cells from them. But it seems there has been a change on how EVE is sending out rejected cells (Tested to be lower than Automotive Grade) for auction to the Chinese market (grey). According to the new...diysolarforum.com
The manufacturer is going to start Marking the cells as Grade B on the qr code on cells that do not meet there testing standard, so anyone denying there is no such thing as grade A vs Grade B will will have to stare at a Big fat B on there cell.