Can someone identify?


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DiggsUt

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Oct 30, 2019
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My nephew passed several hundred 18650 cells on to me stating they are Panasonic 3400mh and that's all the info I got. Most have no wrappings and the few that are wrapped are plain generic shrink sleeves. The only thing on them is some type of bar code (pictured). I did a quick test and indeed, I'm showing them at 3500mh+ on the several cells I tested. Any suggestions as to who/what/where? I'd like to be sure of the discharge rates before putting them into my toys (ebikes and etrikes).

unknown1.jpg
 
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Korishan

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That's gonna be a tough one to try to figure out. Cycle testing is about the only way to help narrow down the possible cells.
Are they new cells? No soldering or tabbing on them?
 

DiggsUt

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That's gonna be a tough one to try to figure out. Cycle testing is about the only way to help narrow down the possible cells.
Are they new cells? No soldering or tabbing on them?

They appear new. No tabs, no dents or scuffs. Some of the wrappers have old glue on them it seems but no writing or other identification.
 

Korishan

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Ok, at least being new that helps to make sure they are reporting accurate capacities, not degraded.

Does the bar code pull up anything when you scan it?
 

DiggsUt

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Does the bar code pull up anything when you scan it?

The reader apps on my phone do nothing when I try to scan the code. I was sure to include the photo in large format so others with different software can try.
 

Korishan

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The reader apps on my phone do nothing when I try to scan the code
Yeah, I tried the same thing. No go. I wonder if the image needs to be inverted, the dots are the white space, and the silver is the black space

Degraded? Heh! I've never seen 18650 cells that test above 3500mh.
Them testing coming in at 3500 shows they are most likely new, and they haven't aged much or at all. 3400mAh is pretty much the max capacity for 18650 cells. Kinda like you can't put more than 5 gallons in a 5 gallon bucket :p
 

100kwh-hunter

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Probably a long shot:
Tesla cells?
If so don't discharge them below 65%
Apparently they tend to get unstable when discharged below that
 

DiggsUt

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Apparently they tend to get unstable when discharged below that
Never heard that of any 18650 before - hmmmm.....

Possible Tesla cells? Interesting. I didn't think being that high of mh they would have the discharge rates for that.
 

Oberfail

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Jun 22, 2021
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Not really, since 99% of the supply went to Tesla. What does the top look like of that cell?
Just google for the cells specification.
 

100kwh-hunter

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Probably Tesla Cells, as they use/used Panasonic 3400mAh Cells that are unwrapped.

Source?
One of my friends tested a lot of tesla cells, he came with this conclusion.
When he only tested for IR (5k+)instead of discharge (5k+)for SOH (2x testing for soh per cell) the cells seems to settle down.
I don't know anything about those cells, apparently there are other cells that behave like this, like some Sony cells.
This is all i can tell you, sorry
 

DiggsUt

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These are 18650s like I've never seen before. All of them are in the mid-3500s with some exceeding 3600mh. I'm used to running a couple of batches of cells a day for capacity testing but these take so long to charge and discharge I can only do one batch a day. (A good problem to have.)
 

cak

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My only contribution would be that the only cells I have seen with similar high gloss silver metal are the Panasonic cells I pull out of ring packs. Those cells also have thin walls. They are technically 3200mah but depending on test conditions I could see them reading higher. An AC IR reading would help find a likely candidate, the Ring Cells are around 30-40mohms. Overall based on all that info seams likely that they are the Tesla Panasonics like folks are saying. This makes me wonder if the Ring cells are just the low grad cells that get rejected by tesla.
 
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