damaged XTAR 18700 - what to do?

Howdy all,

the sixfink is back after a summer full of work, extensive use of duraloops and the sad loss (theft?) of my EZAA which Boaz had sent me for my birthday. The neat little double-A nitecore has since been replaced by (drum roll) another one of Boaz's EZAA as I couldn't cope with one light less in my collection. A couple of projects are still waiting for my attention on the shelf, and you'll read more of that soon as I get more and more free time over the cold period of the year due to decreasing order situation, as usual.

Anyway, the reason for my posting is one of my XTAR 18700s. After I ran two of them flat to the ground (reading 0.09V on my Gossen Metrawatt) in my L2P/solarforce T6 single mode, I stored them carefully until I would buy a hobby charger. Not carefully enough, though - last night one of them rolled off the lowermost shelf of my cabinet, hitting the floor tiles. It fell from less than one foot, or less than 30 centimeters, for that matter - still enough to split the plastic foil covering on the back end, or negative terminal, which also houses the protection circuit.

The cell now reads 0.3V, but I am absolutely at loss what to do with it, fearing the circuit might have suffered any damage which could not only render the whole cell inoperative, but also posing a risk to recharge and use. Also, I don't really like the damaged protective covering.

question - what would you do?

thanks a lot (it's good to be back!),

Simon

Can you take a photo and post it?

There's no visual damage at first sight - the plastic covering has cracked right along the edge and can be lifted off with a fingernail easily.

Maybe I'm too cautious here, but you never know...

From what I've learned about lithium battery technology, those cells are now dead and should be binned.

It would quite likely be dangerous to attempt to charge them. Don't do it in the house.

If these are protected cells, how did you manage to run them so low?

Toss them. They won't be any good anyway. Going below protection voltage is bad enough and seriously damages the cell. At 0.09V? I'm pretty sure it's a goner and a fireball waiting to happen.

I'm telling you, people,

I just stuffed them in a P60 host with a solarforce T6 single-mode dropin.... and boy, do they get low!

It was amazing to look at the ridiculously low shining emitter. At daylight, you wouldn't even noticed.

is the cell really gone for good?

Am I misunderstanding or are you saying that you ran the cells dead (which you shouldn't do) and then just let them sit (which you REALLY shouldn't do)?

the longer you leave it like that the harder it is on the cell ..i'm curious why you put the last bullet in it at about 2,5 you should have jumped and realized you'd already made a mistake and let it go too low .. abuse on lithium ion is overcharge and over discharge .. i'd charge the thing like people are saying .. outside up to about 3.5 and give it a rest for about a day checking to see how badly it falls off at rest and if it seems ok I'd take it all the way to 4.2 and then check it over a few days at rest .

i've never tried to take one from that low I'd probably be tempted to do it with a xstar because it was a new battery .. This is some pretty solid info about batteries from our brothers on the dark side :P

http://www.candlepowerforums.com/vb/showthread.php?229717-Low-voltage-on-18650-cell

worth a read .

I've managed to damage the coating of an XTAR 2400mAh before. It fell from about 1,5m to floor tiles. I wrapedd it with electrician tape and stil use it since the crack was around 1cm. Performing good despite is only used as a test battery mostly. Occasionally on "duty".

Yes, to stop the confusion, I admit it-

I ran the cells dead empty - partly from the misunderstanding that protected, rechargeable Li-Ion cells would be immune against deep discharging; and partly I did it on purpose, too. One has to witness for oneself what a cell is capable of. Sacrifices serve a purpose, sometimes: I just wasn't all that aware that I was actually sacrificing two good cells. Oh well, lesson learned...

So, no anti-deep cycling protection has kicked in on none of the two XTAR 18700s in question, if there is any at all.

Both cells have recovered to around 0.35V now (read: "zero-point-thirty-five"...). I just might hook them up to a hobby charger and get them a very, very gentle charge outdoors, for a long time, and see where this might be going.

Call me dumb, but sometimes you just have to break stuff to learn something. Too much has been written on the net, already; there is no substitute for 1st degree knowledge.

on a side note: a XM-L T6 just looks plain gorgeous when it's run ridiculously low. Such a huge emitter, and such a soft, barely noticably glow! Smoother than the blushing of a gorgeous babe who just got - err, let's not go there. Family oriented site here....

Whish I had taken a picture of it (i.e. the emitter!), but I cannot even take decent ones of GITD stuff, which is much brighter than a T6 on a deliberately murdered rec' li-ion.

Simon

p.s. @ Boaz: Thank you Jeff for your concerns and your PMs. Appreciate them greatly! Oh.... is deep-cycling a duraloop a bad thing, too? I've done it several times, albeit not as low as the XTAR 18700s I have, and charging time and runtime haven't got any worse. I do charge them @ 200mA for about 12-14 hours, after they are so low they will only produce a tiny little flash from my XR-E-R2 equipped mini m@glite.

Yes, just like that. Ran them dead, then let them sit. Do I keep potential grenades on my nightstand, now?

'loops can take a helluva beating and keep on going. Discharging them fully is perfectly fine. I wouldn't store them discharged intentionally, but they can spend quite a bit of time in a discharged state without damage.

The XTARs on the other hand, need to be recycled. They are permanently damaged and most likely unsafe and their capacity will have suffered greatly even if you do manage to revive them.

at 12$ each i'd have put a charge on them yesterday .. they will snap to 3,5 in less than a 1/2 hour on a cheap charger ..i have no idea why or how but the first part of the charge seems like the easy part ..anything i see as low I put a short charge on and magiclly it pops back too 3plus volts ..i see it as a person whose heart has just stopped ...Zap him right now .. because waiting just a little bit will guarentee no blood will go to the brain and you'll have real problems .. Charge the damn thing .

I am currently playing with about 100 old laptop cells and no real charger ..So I hate to see you intentionally toast 2 good cells

I just recycled lots of cells that would have given you that low xml light you seem to have enjoyed so much ......Are you smoking a big bong ?? Are you vapping reefer ?:P.. let us know how the cell reacts i'm curious as to the real details ..how long it was down and how it reacts now at 4.2 and if it freefalls at rest ..Now the real experiment begins .

i agree the nimh duraloops are tough as nails .. if they hold any chagre at all they will work .. if they show zero they are dead .. it will be obvious when nimh's are dead ... they're dead.

Actually, no.

Would it be helpful?

update:

I didn't get myself any weed yet, but I'm sure it wouldn't have been beneficial for my XTARs anyways.

Long story short, the landlord sneaked in last night while I was at work on one of those insane 36hrs shifts; she usually does that when I cannot fetch the mail from the mailbox. What she usually doesn NOT do is touching anything; yet this time she did. Both of the rec's in question were on my desk when I left, but when I returned, they were both on the floor - and both quite dented in and deformed. Too tired to fetch the multimeter now and check voltage and resistance, but I think the cells might be gone for good.


more on that later, I'm in the mood for a couple of strong brews now (thankfully none of the cells have vented off... there's not even a door between my office and my sleeping room)

Simon