18650 vs prismatic - which is safer?

Warren said:

That would be awesome! Please do. Thx

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Here you go...turn up the volume to hear it.
[youtube]UJUVYEUPzFY[/youtube]

For reference, doing the exact same thing to a normal cell does not make this sound. Also, to clarify...my memory kicked in a bit more...I am pretty sure this cell was also performing poorly under load. i.e. it was sagging way more than the rest, so there was that indicator also.

john61ct said:

So a fault with the cells used, not the pack design??

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Seems like it to me!

Warren said:

john61ct said:

So a fault with the cells used, not the pack design??

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GM is claiming two "rare" defects in some cells. They believe a fire requires both defects in the same cell.

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Dunno what the other part to it is, but a ruptured from factory cell seems like enough of a defect to me. :lol:

Cheers

Cowardlyduck said:

I reckon I have a pretty good idea...seeing as I've built a powerwall using these exact LG cells salvaged from an as new Bolt, imported over to Australia.


Cheers

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Did you take these cell out of a car, or did someone else just tell you they were " Salvaged from a Bolt"?

'Cause I have seen many sellers ( BHU, JEHU's) say they are salvaged EV cells and they are NOT. THey are from somewhere else. I have seen them in the modules, and I have seen them sod new,, old, loose, not.

So did you see the car that cell with the red X sharpie on it.. actually come out of a Chevrolet? Or did your seller just say " Its a car cell"?

Didja get teh Julian date on the cells? Certainly that is important tinformationsz.

Cell is obviously compromised ( wrinkles) and I do not see the OEM welds?

The label bars code on the cell has been wiped away with an alcohol solvent? I see that ALOT on Chinese sellers trying to sell me things.

What is the part number on that cell that is supposedly " From a Bolt?" It certainly has a part number, bar code, and Chevrolet Julian date printed on the cell, right?

THIS is a cell that came out of a Chevrolet car.

See the difference? Part number. Julian date. Ultrasonic welds on ( Chevrolet's patented ultrasonic welding head, there is info online about it) ( even though it lookl like any other ultrasonic WAFFLE PATTERN, I have seen patent documents online about it.. ) the tab... Three things I have seen, EVERY CHEVROLET, does cell have.

THe ones in your vid are ... having the full tab and oblong bolt holes? THey should look like this: With the Chevy U-shaped busses and the ultrasonic welds: YOU absolutly CANNOT remove them from the LG VISTA 2.0 without cuttting the tabs with scissors or a Dremel...


Part number, Cell name, and Julian date:


Chevrolet welded assy, with the tell tale marks from the Chevy welding head. I know those crinkles very well, lol, I have cut a few hundred of them out for ebike packs.




NOT a BOLT.. Just because it has a "LG Electronics VISTA 2.0 Cell Module" does NOT mean it ever was actually in a BOLT.


I do not know where the cells might have come from if they were not ever welded? Numbers wiped off, or did you do that? Certainly not from a production car that ever passed QC.

Thank you both for posting. As to cylindrical vs pouch:

https://www.autoblog.com/2021/07/30/tesla-megapack-battery-fire-melbourne-australia/

https://electrek.co/2021/07/30/tesla-megapack-caught-fire-giant-battery-project-australia/

I agree that it looks suspect...I was the one who wiped off the barcode with alcohol solvent actually as I was cleaning off markings I made myself.

I bought these from battery hookup. So they seem legit to me, but you're right, could be anything....so far however I haven't seen battery hookup doing the dodgy like you described, so I'm fairly confident they were actually from a bolt. The cell tabs were quite short also due to them being cut out from the packs they were in...quite annoying to work with actually.

Cheers

Dogdipstick, thanks for posting those pics.

Would you please post the exact dimensions of the Bolt cell in the pic above?

In case you have been under a rock this week. GM has now stopped production of the Bolt, and EUV EVs, and is recalling 142K vehicles globally for the risk of two manufacturing defects – a torn anode tab and folded separator in the same cell. They are setting aside 1.8 billion dollars for this recall. Initially, they thought the problem was only with Korean made cells, but now it is apparent that the problem exists in Michigan made cells as well.

LG uses a patented bi-cell manufacturing process, which rolls a bunch of cell part stacks together in a spring roll of more separator material. This process was intended to make their pouch cells less prone to these sorts of problems....oh well.

Pretty much every legacy maker on the planet is using their cells in one or more of their cars. Most have now had some spontaneous fires after charging. Here is the latest I am aware of.

https://youtu.be/x4NAKQst7Lk

Warren said:

In case you have been under a rock this week. GM has now stopped production of the Bolt, and EUV EVs, and is recalling 142K vehicles globally for the risk of two manufacturing defects – a torn anode tab and folded separator in the same cell. They are setting aside 1.8 billion dollars for this recall. Initially, they thought the problem was only with Korean made cells, but now it is apparent that the problem exists in Michigan made cells as well.

LG uses a patented bi-cell manufacturing process, which rolls a bunch of cell part stacks together in a spring roll of more separator material. This process was intended to make their pouch cells less prone to these sorts of problems....oh well.

Pretty much every legacy maker on the planet is using their cells in one or more of their cars. Most have now had some spontaneous fires after charging. Here is the latest I am aware of.

https://youtu.be/x4NAKQst7Lk

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WOW!
Yep I was living under a rock this week (trying to avoid the constant depressing news cycle) so thank you for posting!

This is exactly as I suspected, and is really annoying to discover both from an EV adoption perspective and many like me who have put massive time/effort into using these cells in various projects.

That being said, given my video above, I wonder if there are way's of detecting this issue early? i.e. could all the cells with this issue be making that strange sound under heavy load? Is it possible that because a test like that would not normally be part of the manufacturing QC it's something that was missed and this is an easy way to tell?
I'm not really sure, but it would be awesome if a simple short/sound test was the indicator for this issue.
If it is, then the monumental amount of used cells about to hit the market would be a huge boon for DIYers.

Cheers

So long as they don't burn themselves nor any buildings

Cowardlyduck said:

could all the cells with this issue be making that strange sound under heavy load?

If it is, then the monumental amount of used cells about to hit the market would be a huge boon for DIYers.

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The defective cells do not have a hole in the pouch. They have a torn anode tab and folded separator.

GM and LG will not be selling these cells on the used market. They will be recycled.

Warren said:

The defective cells do not have a hole in the pouch. They have a torn anode tab and folded separator.

GM and LG will not be selling these cells on the used market. They will be recycled.

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My cell may not have had a hole...that was just my assumption. All I know is it made a sound under load. Could it be that the sound is somehow related to this issue?

It's a shame they won't be seen on the used market, but I guess liability etc. will prevent that. I do think they could be useful as grid level storage if appropriately configured and spaced. i.e. build it in such a way that it doesn't matter if one group of cells goes up, unlike the recent Tesla event.

Cheers

Im sure LG have “World Class” manufacturing ,process control, and inspection/QA standards,....but obviously some defects have slipped through the system.
Remanufacturing cells for 142k packs will take a while and they will have to enhance their inspection processes to ensure there is no repeat.
Maybe they have figured a way to detect the problems in a assembled module or even a pack, so they can “recycle” complete modules without having to remanufacture new pouches ?