Can you really buy Grade A cells for Grade B prices?

robby

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May 1, 2021
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I currently have 16KWh of Fortress eFlex batteries and am thinking that I need about another 10Kwh of batteries to get completely off the Grid. I would love to buy two more eFlex packs, but at this time as I just cannot see that happening. So I was contemplating buying LifPO4 prismatic cells and making my own packs, but saving half the money only makes sense if you get more than half the amount of cycles without issues. If it's half the amount or worst yet less, then the extra work in construction makes it a bad investment.

I came across this interesting video and came to the conclusion that with this much testing going on it would seem highly unlikely that a Grade A cell is slipping out of a factory at Grade B prices unless it's intentional.


As you can see, swelling of the batteries is just one of the many reasons why a cell is rejected and sold as grade B.
A lot of the other issues are hard if not impossible to detect. Also the barcode on the top is not a guarantee of anything.

I had a talk with Fortress Batteries and they confirmed that the high prices you pay for Grade A cell packs from them and others is because they are tested to these high standards to assure that companies like them do not get a bombardment of warranty issues during the 10 year warranty period and also because these batteries are not just used in PV systems but are also used in critical systems.

I am interested in hearing other peoples thoughts on the subject.
 
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RayfromTX

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Jul 17, 2021
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I am using 18650 cells for the last 10 years. Some of them are the really cheap ultra fire cells. The lifepo4 cells I'm buying today are a much more robust and durable chemistry. I have a suspicion that most or all of them will still be in service 15 or even 20 years from now. Having said that, my wife and I are on our 4th and 5th Prius since 2004. We have driven them for hundreds of thousand of miles and I've replaced one battery pack. I'm sure that most of the pack was still fine. With that in mind it is very important to me that I can test, monitor and replace individual cells if they go bad or consolidate cells into fewer packs when some of the cells get long in the tooth.

The reason I get the seller to sell me Grade A cells isn't because I'm convinced that it is what I'll receive. It is because I want to establish a high expectation with the seller and with my credit card when what I receive isn't good enough to serve my purposes. I don't want to get garbage and have my complaint be met with the statement of what did I expect from grade B cells.
 

robby

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May 1, 2021
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The reason I get the seller to sell me Grade A cells isn't because I'm convinced that it is what I'll receive. It is because I want to establish a high expectation with the seller and with my credit card when what I receive isn't good enough to serve my purposes. I don't want to get garbage and have my complaint be met with the statement of what did I expect from grade B cells.

I get what your saying and I understand that at least it gives you protection from visible and measurable issues.
But if there really is no such thing as Grade A cells at this price point your kind of just hoping that your not getting a cell with visible problems like bloating or abnormal voltages. My suspicion is that the "Slitting / Cutting" that he talks about at the 4:20 minute mark is just as he states, the major defect that Grade B cells suffer from. He states this is what reduces the life of the battery significantly and a shorter life is not something you will detect until long after the purchase is concluded.
 

Posplayr

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May 27, 2021
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Excellent video despite the difficulties with translation into English. The intent to provide clear information is abundantly clear.

Seplos Technology state quite clearly that the self discharge is the indication of greatest risk.

However, without diving any deeper into this message in general is that there are a variety of factors that the manufactures uses to classify cells based on their ability to meet 10 year warrantied life. So the 30% price premium is related to that set of factors which in the manufactures opinion will satisfy the 10 year warrantied life.

If you don't need 10 Year expected Warrantied life then buy grade B and an extra couple to make up for short falls. If you want long life go grade A. Never buy grade C (high self discharge risk) which is what you might be getting with grade B cells.
 
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