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gcrank1
Member
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# Posted: 2 Apr 2021 11:40am
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Matched? Grade A,B or cast-offs?
Still need assembly and BMS, compression and a case.
Is he going to build one for you gratis to trial? (hint 
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paulz
Member
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# Posted: 2 Apr 2021 01:11pm
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I don't need one but he said he give you one.
Is there a grading system? He's coming tonight to pick up and I can ask more specifics.
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Steve_S
Member
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# Posted: 2 Apr 2021 01:36pm
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1st look at the QR Codes on the cells.
Clear & Intact is good.
Scratched off or missing = BAD - RUN.
Fuzzy and not clear - possible knock off or repacked B grade.
Here is a big listing of Cell Manufacturers with images of their cells. Many may "appear" similar but will have specific vents of variations on the cell contact pads (round, square, oval)
Index of Lifepo4 Prismatic Manufacturers. (DIYSolar)
Everything you need to know about assembling a battery pack is in that Luyuan Tech Doc I posted earlier in the thread. It's also good to know how an LFP Pack is put together.
Current prices averaging for 272AH & 280AH cells are about $90-95USD for Bulk Commodity Cells to $125-135 USD for Factory Matched Grade-A.
Bulk Cells are usually on the edge of the general Grade-A Spec, meaning at the low or hi side they may deviate more than the other cells.
Matched cells keep the same IR and deviate minimally through their operating range.
Cells provided by Cell Brokers to vendors (most common) can be anything from Grade B- to A-, New Old Stock or Blems with minor flaws. This is why it's important to know the vendor & where their supplies come from unless dealing direct with a manufacturer (they generally do not retail less than 500 pcs MOQ.)
BMS' can be really cheap or really expensive depending on features, functions, capabilities and of course quality.
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paulz
Member
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# Posted: 2 Apr 2021 02:26pm
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90x4 must be what he's referring to, I'll find out more tonight.
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gcrank1
Member
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# Posted: 2 Apr 2021 03:49pm
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Id sure be willing to trial one and report  , downside I expect will be Id have to come pick it up.....
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