18650 Strange Mottling Under Shrinkwrap

I recently purchased a light from a friend, an Ultrafire RL-2088 (6-die Osram). With it came 3 x Ultrafire red and silver label 3000 mAh 18650's which were bought with the light perhaps 6 months ago. The batteries have had little use and only a couple of charges and have only ever been used as the set of three in the RL-2088 which has worked flawlessly and showed no unusual characteristics.

One of the batteries is showing a strange dark mottling under the red shrinkwrap. Almost like something has leaked or something was on the surface of the battery when it was wrapped. I do not know it the cell was like this from new or this has developed over time.







Other than the mottling the battery shows no sign of damage, misuse or venting (see pics). Resting voltage on all three cells is within a couple of hundredths of a volt. Any battery experts have an idea what this, and more importantly as this battery is used in a multi-cell light if it is safe to continue using?

Thanks for your help,

Olef

I wouldn't even use it in a single cell light - it's a prime candidate for recycling.

Away it goes! A new cell is $5 - not worth risking injuries for.

I have never heard of "porous" metal being used as battery canisters...but I have seen rust when NewBie peeled away an earlier generation BatteryStation cr123A...I think its the same thing your looking at, regions of splotch under the wrapper.

I'm assuming sheef-life is the equivalent of shelf-life/10?

A good example of a loose Li-Ion cell that, in the original manufacturer's opinion, didn't make the grade for use in battery pack construction. You never know what you're going to get. Yes, there is a reason why "CheapFire" cells are less expensive.

Dave

Hello Olef,

If you plan to recycle the cell, you may want to remove the shrink wrap to see what is actually going on. It may be rust.

Tom

but the rust might be "caused" too, the nasty solventy stuff that slowly comes out of the top (when bad), could be causing abnormal corrosion from PH offsets.
that cell or another one might be open somewhere, but only enough to be slowly leaving to the air. an open cell will still work good until more of the Stuff inside dries out and oxidises.
that particular cell has a few reports of it SLOWLY leaking, so that is an even better reason to suspect that it might not be perfectally sealed.

or the guy just cleaned the light before he sent it out and any moisture left inside just sat there.

check the light itself too.
and wear protection when you do a look see.

Thanks for the replies, I think this one is going to be recycled. If so I'll do as Tom suggests and do a little careful dissection, and post up the results for future reference.

Olef

Just to report the inside of the light itself and the battery carrier show no sign of contamination so it looks like it is confined to underneath the shrinkwrap. The other two cells look fine.

Bit of a blow really, AW 18650's cost £12 (~$19) in the UK and I would never put just one in a multi-cell light with two Ultrafire's... so to get my light going again will set me back £36 (~$57). This little episode has kinda put me off cheapies but I guess I'd rather have a non working light for a while rather than an exploding one

Olef

Olef said:

Bit of a blow really, AW 18650's cost £12 (~$19) in the UK and I would never put just one in a multi-cell light with two Ultrafire's... so to get my light going again will set me back £36 (~$57).

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The blue or black TrustFire 18650s seem to work good enough.

Order direct from AW here:-

http://www.cpfmarketplace.com/mp/showthread.php?t=200812

Only works out at £26 or £28 inc insurance.

mfm said:

The blue or black TrustFire 18650s seem to work good enough.

Click to expand...

.
I'm happy with my two blue (unprotected) and my six grey (protected) Ultrafire 18650s, but that might be just good luck ... I can't justify £12 for a 18650, so will stick with what I've got till I need to buy a couple more 18650s in a few years time ... Only five of my 18650s are in torches, so with three spare I shouldn't need to buy for a while ... Even if three out of the eight fail, I will still have a 18650 in each torch ... I shall just wait and see, if or when I need to buy any more.

My charger only takes the 18650s up to 4.21 volts and I do check the voltage regularly during charging before putting them back on charge ... The current drain on my Solarforce L2s and my modified L2i is not excessive and I don't let the cells go down too low before recharging or topping up ... So my cheap cells have a fairly easy life ... I think if I needed the torches for more critical use or was using a current hungry torch, perhaps then I might go for the more expensive cells.
.

Just out of curiosity' does it have a sort of sweet and sour electrolyte smell to it?

I've not known many things to attack shrink wrap, I'd agree with the better safe than sorry idea.

I'd carefully slice off the shrink wrap, best bet is it's rust, but I'd toss it.

No smell at all. I'm leaning toward rust myself. I'll take a blade to it tomorrow I think...

Olef

Well, I took the cell to work and removed the shrinkwrap. Apologies for the picture quality, my SLR was at home. Some rust-like corrosion was present on the metal surface but there was also much blackening of the shrinkwrap (like burns) and a very noticeable sharp / sweet chemical smell. No obvious point where a leak came from but the top of the cell wasn't sitting too straight as you can see. I didn't go any further, just wrapped the cell in plastic and recycled it. Thanks everyone for your input :thumbsup:



Olef

luv them pics.

VidPro said:

luv them pics.

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:thumbsup:

Olef

If the smell was strong then it was probably leaking small amounts of the electrolyte and corroding the cell, if it was a very mild smell, then it make have been left overs from manufacturing that attacked the cell.