Lithium batteries going wrong

Caution! throw that 16340 to the garbage! (the one received at 0 volts) and ask for replacement. That battery can become in "unstable condition" and explode, fire your house, etc.......

I would toss it without feeling bad at all.

Save the cell but mark it so that you can keep track of it. Also, do not use cells of different state (charge, wear, age, manufacture etc) together in a series configuration.

Hello all,

has there ever been a case of a single cell explosion?

I only use protected cells and only single cell flashlights - but I must admit, sometimes I do not measure the voltages.

How risky is this?

Thanks a lot

Only when something silly has been done like dead shorting it for a while. That said, I did accidentally do this. The cell leaked and was destroyed but there was no smoke or flames. Try hooking it up to a car battery charger set to 5 amps and you'll get it to blow - but that would likely make an NiMH leak violently at best too. You can make NiMH cells go bang - you just have to work hard to do it.

Your chance of being killed by a dead fish dropped by a seagull while in the Sahara Desert is considerably higher. Single cell lights are safe enough. Most exciting stuff with lithium cells is when they are being overcharged or charged at too high a current. I would toss any lithium cell that was below 2.5V on standing for an hour or two. It will probably be safe, but it will have a small fraction of its original capacity. Anything that had been charged above 4.35V I would be happy to use but would not attempt ever to recharge it again. Some of the newer very high capacity 18650 cells are designed to be charged to this voltage - the Chinese stuff most of us buy emphatically is not.

The cells are cheap enough and my flesh isn't. In general to give the cell a chance to live beyond a few cycles it is best to keep discharge rates below twice the capacity unless the cell is specially designed for high discharge rates like the AW IMR cells or Sony's equivalent. So for a 2400mAh 18650 I'd not want to discharge it at more than 4.5-5A. I have had an unprotected 18650 provide 9A until flat, and recharged it several times. It didn't last a year but it didn't do anything exciting either - just stopped working.

The risk is pretty low, but not zero. I've never really given it a thought but I do pay attention to what voltage they are coming off the charger. Above 4.35V Bad Things are likely to happen.

All the dead lithium ion cells I've had have failed gracefully - they just wouldn't hold a charge any more. One of them actually showed a small negative voltage - I most certainly did not try to recharge that one.

For fun, we once connected a dead RCR123 across a 200A welder then turned it on. That stuffed something like three kilowatts into it.

Briefly.

Best to do this outdoors and I didn't think to bring a camera.

Doing that to almost any other battery would have the same result but wouldn't have hot hydrogen fluoride and burning lithium metal as a door prize.

Almost everyone gets away with using and abusing lithium ion cells with no harm to themselves - not that I am recommending this - all that happens is that the life of the cell is drastically shortened. I would check voltages as a matter of course in multi-cell lights.

At least when they came off the charger.

And maybe occasionally in between charges.

But then there is no light I own that I would not be prepared to throw as far as possible and then run if I thought the cells in it were doing Bad Things.

Doesn't 0V just mean the the protection circuitry tripped? My understanding is you should be able to charge it and the circuitry will reset itself. Not sure why the charger wasn't happy with it though.

My guess, and it is just a guess, is that once it had reset the protection circuit, it was still at a lower voltage than the charger was happy with applying any real current to.

This may be a higher voltage than i would consider it unsafe to recharge it from.

Don,

thanks for the time you took writing that.

I was planning the give 2 cells as a gift and decided to check them. One was flat, so I removed the protection board and it showed 3.6V. More trouble to repair than to order a new one, so it got tossed (even though the thought of using it without protection crossed my mind.

I do not abuse the current draw (low mode most of the time) and recharge them long before they reach 3.7v, so I guess I'm not even abusing them, but your example was priceless.

In fact, the battery was shorting the charger. It took a while at 100 mA in the power supply for the voltage to rise from zero to 3 V. Now, a few hours later, the self discharge has progressed so the cell voltage is now 3.98 V.

I suspect that is has internal dendrite formation or the protection circuit is draining it. In some weeks I expect the voltage to be almost zero again, so the battery is garbage. I will keep an eye on it.

Lithiums aren't nearly as fragile as some on CPF make them out to be (basically to promote the expensive ones their vendor sells). Those idiots are always going on about slight breaches over 4.2v, when the manufacturers themselves spec the batteries to 4.2+-0.05. Then they would turn around and recommend a PILA to charge 10440, at way over the current limit, which is by far the worse of the two possible indiscretions.

Using hobby chargers are also not as safe as some claim. Crappy DX chargers are shipped out to thousands and if people's house got burned down because of it, we would know about it. Hobby chargers require DIY rigs and mistakes there are going to be lot more likely than any mass manufactured item.

You'd probably want similar cells in a multi-cell config (and a sanity check before loading those) to prevent reverse charging, which is one of the "common" causes of failure. Protection is a good thing, because it's practical to save cells from overdischarge and can prevent shorts, so buy cells with it, but it's not a huge deal in buck drivers since those'll dim anyway to warn you of low capacity. Other than that, don't fret over it. You use a meter, so you're already ahead of most people.

[AOL]

Me too

[/AOL] :)

You got it!

Above 4.3V worry about it - as in toss the cells.

Below that.

Don't worry about it.

In single cell applications.

In multi cell devices,use the voltmeter. Or there is a small chance of losing fingers.

Your fingers.

Your choice....

That's friggin' hilarious! Laughing Laughing Laughing

Thanks for the laugh Don.

It is now my new sig. Hope it's ok with you Don.

Man, I'm still laughing......must be the beer......but still.....Laughing

You may want to edit it without the quote tags, because it's causing every thread you post in to lose its background.

How's that?

:)

Now, after 11 more days the voltage on the bad "flame" cell is 2.82V, time to recharge (at a safe current). I will eventually remove the protection board to see if the naked cell discharges itself or it is the board that leaks.

By the way, two 14500 "flame", bought together with with the problem cells, keep their voltage fine.

I was given an AW 2200mah cell awhile back that was reading 0v.

This thread reminded me of that and if it would be possible to resurrect it. After carefully removing the plastic coating and the protection circuit, the bare cell read 0.284v. Plans on slow charging it have now been cancelled. Had it read @ 2.6ish volts, I would have been tempted to trickle charge it.

You can try putting it in a charger. At worst, probably nothing will happened. Sometimes it'll charge up fine. I would highly recommend a DMM when working with lithiums.

battery can't not be charge for a long time. Maybe this is a problem