New old stock brand 18650, does it really matter?

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rg12

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Jul 26, 2014

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• Jul 11, 2018

• #1

Hey guys,

Did anyone really test the performance difference of brand new old MFG cells?
I have a customer with 2 year old brand new Samsung 25R cells and he is afraid of using them and then me and my colleagues had a big debate about how much it matters/doesn't matter.

Any testing done on that subject?

 

Hwy89

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Northern Arizona

• Jul 11, 2018

• #2

No real testing but I'm still pulling cells from four year old Tesla packs that seem to be fine. They all are still at 3.6 volts and when capacity tested still output 3300to3500 ah.

 

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Punx0r

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England

• Jul 11, 2018

• #3

Probably very close to original performance if they have been stored somewhere cool and at storage voltage.

An internal resistance & capacity check on a few random samples will probably tell you all you need to know.

 

Overclocker

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Philippines

• Jul 11, 2018

• #4

25R is supposed to be an NCA cell so calendar life should be good. i have several dozen panasonic NCR 2900's (NCA chemistry) from 8years ago that are still performing almost like new.

do a discharge graph to see if they're still performing like new:

 

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rg12

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• Jul 11, 2018

• #5

I think the biggest concern is internal resistance rather than capacity loss.
Will test when I get the opportunity.

 

eee291

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Burgenland

• Jul 11, 2018

• #6

rg12 said:

I think the biggest concern is internal resistance rather than capacity loss.
Will test when I get the opportunity.

Click to expand...

Agree 100%, had the same thing happen with some 8 year old A123 Ultra B cells. Ir went from 1.6mOhm to 5-7 for most cells, even after a few high amp discharge cycles. Before that they were sitting at 16-30mohm

 

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Philaphlous

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• Jul 11, 2018

• #7

Best I can tell is my ncr18650 panasonics are 8ish years old never used in storage... Still perform like new, don't have testing methods to measure IR but they're holding the same capacity as if new... And funny thing is when I got them they were all around 2-2.5v so pretty low... I'd consider them my beat batteries...