A123 cell has a puncture,is it usable?

[flexy]

I just received my A123 cells from Victpower, I found one with a cut in the bottom.
It also had some droplets of liquid on it, I'm not sure if this came out of the cell, it looks like air has got into the pouch so it doesn't feel as rigid as the others (I guess they are vacuum sealed).
the cell measure 3.27V identical to the rest. Would it be safe to keep this cell or will the puncture cause degradation?

[ZOMGVTEK]

It's not something you want to use when the pouch looses the seal.

Is the 900mAh sticker to fool customs or something?

[flexy]

I think it must be, they were listed as 900mAh on all the docs.

They seem to package them in boxes of 14 cells, this must be the optimum for postage weight/volume.

This particular cell came in a box of 6 so they weren't as rigid as the the other packages - and may have been damaged as a result

[el_walto]

Throw it out.

[miuan]

let me guess, you have ordered no spares and now looking for an excuse to salvage this one. horrible idea. it may be ok just sitting on the desk, but start using it, add some shock, temp and moisture changes, and the cell could slowly degrade. i've carefully punctured lipo in a similar way with no apparent ill effects, but that cell would never make it into my pack again.

[dnmun]

the term is 'hermetically sealed' and the pouches are assembled inside a machine where the atmosphere is totally controlled to prevent any moisture or humidity to reach the lithium on the anode and the lifepo4 cathode mixture since moisture causes the lithium to oxidize. and yep it is a vacuum to suck it all tight.

you are the first person who has a clear reject delivered to you. i expect they will replace it even though they should pay shipping, they won't i expect. maybe buy an extra one or two when you contact them so the shipping cost is not totally wasted.

[liveforphysics]

It's toast. Once they get oxygen inside, they are a hazard. Don't just throw it in the garbage either. Destroy it with overcharge, or slash it open in a bucket of water (outside obviously) and leave it alone for a few days of little bubbles until the potential energy is dissipated.

[texaspyro]

It's toast. Once they get oxygen inside, they are a hazard. Don't just throw it in the garbage either. Destroy it with overcharge, or slash it open in a bucket of water (outside obviously) and leave it alone for a few days of little bubbles until the potential energy is dissipated.

Awww, now where's the fun in that?

[flexy]

Message received, loud and clear

I do have some spares but I will ask for a replacement. Strangely, it looks like it was cut on purpose - maybe customs wanted a peek inside such a large 900mAh cell

I wish I knew a local place I could properly recycle these, got some dead headways too, can't waste lithium!

[flathill]

Message received, loud and clear

I do have some spares but I will ask for a replacement. Strangely, it looks like it was cut on purpose - maybe customs wanted a peek inside such a large 900mAh cell

Another casualty of the war on drugz
wouldnt have cut it open if they thought it was a bomb
Thanks for protecting not protecting our safety while looking out for the old boys

[JRP3]

Message received, loud and clear

I wish I knew a local place I could properly recycle these, got some dead headways too, can't waste lithium!

Actually lithium is cheap and there isn't much in the cell at all. Maybe you could discharge it and dissect it just for fun, then put the foils in with recycled metals.

[bigmoose]

Likely cut with a box cutter during all the shipping steps these cells went through.

If you still have the cell and are willing. A photo documented disassembly of the cell would be useful for us all to try to determine what could have been accidentally "misplaced" by the A123 production machinery.

[flexy]

I will have a go, but should I try and discharge it with a resistor across the terminals first?

Liveforphysics method sounds fun (but maybe too destructive)

[ZOMGVTEK]

Resistors are slow. Big metal things dropped across the terminals is faster.

[bigmoose]

Yea, dead shorts are faster; but we don't want to destroy the evidence inside. We have seen lots of fireballs, but I do not think we have seen the internals of an A123 Prismatic yet. It would be great to see inside, au natural, don't you think?

[liveforphysics]

Yes! Dave's idea is much better. Connect a car headlight or brake light lightbulb across those terminals, and let it sit for a few days until the voltage reads 0.2v.

Put on safety glasses, a plastic face shield, a respirator, long plastic gloves, and cut away the foil off the top of the pouch. Then, the safest option would be submerging it outside in a bucket of water for a day to make sure everything is fairly neutralized.

Then begin dissecting (with proper safety equipment on, outside or in a place with excellent ventilation).

[flexy]

I was thinking along those lines, or that gear Ypedal's wearing


This ingredient breakdown was on the docs that came with the cells, not sure if it applies to these cells in particular or it's just safety guidelines for generic lipo.

http://dl.dropbox.com/u/8208701/Electric%20scooters/lipo%20chemicals.PDF

[JRP3]

Is there really that much potential for mayhem with a fully discharged LiFePO4 cell? Especially when I've seen some of you guys holding smoking cells of more volatile chemistries in your bare hands

[liveforphysics]

Is there really that much potential for mayhem with a fully discharged LiFePO4 cell? Especially when I've seen some of you guys holding smoking cells of more volatile chemistries in your bare hands

The A123 pouches can be pretty touchy. If I was doing it myself, I would just cut into it with a razor knife and bare hands and get it done. But I would never encourage anyone else to take my approach, too many things could potentially go wrong, and too many nasty solvents and chemicals that might hurt someone who is into doing the longer-term-staying-alive thing.

[potatorage]

I had a cell that wasn't as tight as the others, but I don't see any noticeable flaws. Is it safe to use?

[flexy]

I have taken the cell apart, here are some pics.
There was a strong sweet smell from the liquid inside ,this soon evaporated.
You can see where the cell was originally punctured the cathode/anode has started to degrade. there were about 60 layers altogether.

Hard to see what might have been out of alignment, without a reference to compare to. I did notice on some of the others what appears to be loose bits of tape, trapped under the case, causing an uneven surface. This might cause problems when they are all under compression in a large pack, causing them to be rejects.





All photos here https://www.dropbox.com/sh/kmnlhfj21ibb22i/Ip4onBU4xq

[bigmoose]

Flexy, THANKS! Outstanding execution of a Destructive Physical Exam! I would bet the "bump" I fell down the center of one of my cells is a full wrap of that green tape. Looks like a straightforward zig zag of the separator with alternate cathode and anode. Each with a tab at the top of thin foil that gets ultrasonically welded together to thick tabs to exit. The kapton tape around the ultrasonic weld almost looks hand applied, but that can't be true. Interesting that there are 3 or 4 layers there. Would have thought automating the process would be one layer of a thicker kapton...

Your capture of the degradation of the plates once the foil pouch was cut is priceless! Thanks again for doing this. We have all learned from your bad cell.

[flexy]

The kapton tape around the ultrasonic weld almost looks hand applied, but that can't be true. Interesting that there are 3 or 4 layers there. Would have thought automating the process would be one layer of a thicker kapton...

There is just a single layer of kapton either side of the weld.
Most of my cells had small dents on the tabs like they had all been tested with a voltmeter by hand (Victpower Quality Control?)
I also had one labelled "test" which had a lower reading than the others, that's not getting picked for the team either!

[bigmoose]

Good catch where the eye is better than a photo! Here is the area that interested me, can you tell what the other two "films" or tapes are that have straight cut edges. So the serrated edge is a single kapton tape.

kapton.jpg (91.82 KiB) Viewed 145 times

[flexy]

The serrated edge is where the kapton tapes from the front and back of the terminal weld come together.
The other cut edge is the bottom of the slightly opaque plastic (or teflon as some have called it) which surrounds the terminal where the top of the pouch is sealed.