DescentBB

Seems Ipod battery overheating issues are not confined to just Japan.

Please see the included link if you have a first gen ipod.

yep, that's what happens when a lipo battery goes into thermal runaway due to overdischarge.

that smoke they're talking about in that article is actually toxic, so you would want to throw it out the window onto the street as soon as you feel it heat up.

Ferno wrote:yep, that's what happens when a lipo battery goes into thermal runaway due to overdischarge.

that smoke they're talking about in that article is actually toxic, so you would want to throw it out the window onto the street as soon as you feel it heat up.

Are there any other manufacturers / devices that are prone to this problem Ferno? I've only heard of it happening with Ipods

I hope they do a recall... I have a 1st gen nano.

All LiPo batteries can burn, or in the RC world, puff. Usually it comes from unbalanced cells within the batteries themselves and when being recharged the charger only detects the lower voltage/amps and continues to charge even though other cells in the battery are already fully charged. The overcharged state can lead to the weaker cell being drawn down too quickly, resulting in letting all the smoke out.

Gekko71 wrote:Are there any other manufacturers / devices that are prone to this problem Ferno? I've only heard of it happening with Ipods

Well, Sony had the same issue with their laptops a while ago. Of course they blamed it on the battery when in fact the main cause of a battery going into runaway is a badly designed charger.

The main cause behind runaway is when a charger senses a voltage that's different than the actual battery voltage. When a lithium polymer or lithium ion battery goes over 4.35v it starts to break down. Once that happens, it now becomes an exothermic cascade reaction, heating the battery from the inside out. If not dealt with right away, the cells will expand, produce toxic smoke and then finally combust.

the only way to deal with that kind of a fire is either with a chemical extinguisher or sand.

CORD wrote:All LiPo batteries can burn, or in the RC world, puff. Usually it comes from unbalanced cells within the batteries themselves and when being recharged the charger only detects the lower voltage/amps and continues to charge even though other cells in the battery are already fully charged. The overcharged state can lead to the weaker cell being drawn down too quickly, resulting in letting all the smoke out.

you're getting your facts mixed up. What actually happens is the charger does sense the average voltage, but when the cells are unbalanced the one cell will become overcharged and begin runaway. BUT if ran and the other cell goes below it's 2.8v threshold it becomes dangerous to recharge. the only way to resurrect that is to charge it at a very low rate until it comes back up to a nominal voltage.

Doh, Ferno, thanks for correcting me. It's been a long time since I've used LiPo's. You are absolutely right. I have a few RC aircraft and LiPo explosions are a real threat especially at the volt/amps these things can produce nowadays so much so that they sell bags to put your batteries in to contain an explosion while they're charging. I have been flying RC sailplanes so I don't need LiPo's, I use NiMh batteries for receiver/servo power.

well, they're not actually explosions, but rather ruptures.

Ever witness a sub-c cell exploding? Goes off like a shotgun shell. A friend of mine was unfortunate enough to be near it and he caught shrapnel in the face.

Ferno wrote:well, they're not actually explosions, but rather ruptures.

Ever witness a sub-c cell exploding? Goes off like a shotgun shell. A friend of mine was unfortunate enough to be near it and he caught shrapnel in the face.

That might be what happened in India recently.

What's interesting to me is that the phone mentioned in the linked article above is supposed to ship with a Li/ion. Does anyone know of any conditions that would cause a regular Li/ion to explode like that?

umm.. thermal runaway, like I just posted?

I find it highly dubious that a prismatic li-ion cell would have enough explosive energy to kill a person. The burns, sure.. but a death from something that small, with walls that thin? There's gotta be more to the story than just THAT.

It has to be something else.

Ferno wrote:umm.. thermal runaway, like I just posted?

I find it highly dubious that a prismatic li-ion cell would have enough explosive energy to kill a person. The burns, sure.. but a death from something that small, with walls that thin? There's gotta be more to the story than just THAT.

It has to be something else.

Sorry Ferno I misunderstood - I thought you were saying that runaway Li/ions don't explode, only burn.

It's possible he hit his head while falling - a common enough occurrence, especially if he was unconscious at the time.

Another posibility is shrapnel punctured his temple - unlikely I know, but the bone there can be extremely thin in some cases.

JFTR

Anything that combusts can also explode…

Put gun powder on a flat surface..it burns, put it in a paper roll, it explodes.

Spidey wrote:JFTR

Anything that combusts can also explode…

Put gun powder on a flat surface..it burns, put it in a paper roll, it explodes.

wrong again.

it has to be contained in a VERY strong container to explode. There's also various types of explosions. a paper roll isn't going to do much other than give off a very low energy deflagration. and before you say that's an explosion, it's not.

can paper explode?

how about plastic?

or dried paint? can that explode?