Boeing 787 Li-Ion Meltdown

[SeanB]

Energy density of those batteries are more than gunpowder and many low explosives though. Only good thing is that they are not shock sensitive but release as heat and low velocity gas only.

Easy test will be to take some and place them in a shake-n-bake chamber, especially ones from an aircraft already in service  for a while. Then cycle it to the measured vibration levels and pressure and temperature cycle it while charging it to the flight profile. Then you can see how it fails. When the first goes the rest will be in a pre failure stage for analysis without actual failure, so you can see how they will fail.

[r90s]

The pictures of the failure are interesting. The construction of the case and the way they appear to have mounted the PCBs on pillars is crude. Though the containment of the failure looks good.
I wonder if we will find out if it was a failure of the protection circuits or was a problem with the cells?

A couple of years ago one day in the lab were I was working there was a very loud bang then the fire alarms went off. I didn't hang around and we had a visit from the fire brigade. The incident was caused by a cycling fanatic who had used what appeared to be genuine Yuasa cylindrical lithium Ion cells for bike lights. He didn't take much care in charging them and one exploded. The cell didn't appear to have any pressure release mechanism, the metal case just ruptured which didn't impress me.

The same happened at a Boeing testing lab in the late 1980's or very early 90's according to a Boeing engineer.
Actually blew a hole through a wall, according to what he said.

[IanB]

I don't do RC aircraft models, but I recall from chats with someone who does that Li-ion batteries are well known to be highly prone to spontaneously bursting into flames. Not from 'overcharge', but while just sitting around with a full charge.

Snopes could do an article on this. I don't think there is any documented instance of a li-ion battery spontaneously bursting into flames without provocation. They are very stable if you don't prod them or mistreat them. For evidence of this, consider how many laptops there are in the world with li-ion battery packs, and look for news reports of laptops spontaneously bursting into flames. There are one or two well known cases of battery recall due to defective manufacturing but the vast majority of our laptops just sit there day after day minding their own business.

The two things that upset li-ion batteries the most are mechanical damage and electrical shorts. Lithium polymer batteries in particular are very sensitive to mechanical damage and you have to be especially careful with those.

The reason for storing batteries partially charged is to extend their service life. Storing them fully charged will cause internal degradation and loss of performance.

[Neilm]

Anyone remember how NiCd batteries turned out to be prone to growing metal whiskers between the plates, and thus self-shorting out? One cure for such dead, unchargable NiCd D-cell batteries was to give them a half second blast of 150A AC from an arc welder. Vaporized the whiskers, and the battery could be charged again.

Anyway, I don't suppose Li-ion battery technology could have some similar as-yet unrecognized problem?
Especially when constantly vibrated and pressure cycled, while maintained at near full charge.

Lithium batteries are prone to something similar if incorrectly charged. If it has been charged at very low temperature or at too high a current (or mixture of both) then you can get lithium metal deposit building up at the terminals. If it is vibrated too much this can then damage the insulator between the layers shorting them out. This in turn leads to a hot spot that can lead to thermal run away.

Neil

[Obi_Kwiet]

My guess is it's a manufacturing defect in the battery that would have been caught if it had been a high volume part. You can bet Boeing paid an unbelievable amount of money for each of these battery packs.

It doesn't really seem like a safety issue though. For a system this big, I can thing of much worse things to go wrong.

[TerraHertz]

My guess is it's a manufacturing defect in the battery that would have been caught if it had been a high volume part. You can bet Boeing paid an unbelievable amount of money for each of these battery packs.

So? Even if that's the case, it wasn't caught, and there's no way to be sure the problem isn't widespread among these batteries.

It doesn't really seem like a safety issue though. For a system this big, I can thing of much worse things to go wrong.

What? What!? These are emergency backup batteries, catching fire on an all-composite very large airliner. How bad should it be, before it's a 'safety issue'?

Edit:

The pictures of the failure are interesting. The construction of the case and the way they appear to have mounted the PCBs on pillars is crude. Though the containment of the failure looks good.

What struck me was that the lid is just a bit of folded metal, held down with two screws per edge. There's no attempt at any kind of accident gas containment and venting to somewhere safe. There are dribbles of the vile 'stuff' down the outside of the case...
The control/monitoring PCBs are in the same space as the batteries. So one battery goes, so does _everything_.
The small gauge white wires (that appear to come from each battery terminal) are bundled together, and terminate in small plugs to the PCBs. Any short in these wires/plugs will place shorts across the batteries.


The whole thing looks like a design by someone with the "nothing can possiblie go wrong!" mentality.

[jerry507]

The box does seem to have contained everything to a pretty good degree though. I'm far far less concerned about the batteries failing, because it doesn't seem to have started a serious fire. What concerns me is that these batteries failing took out a large part of the avionics, and there didn't seem to be any warning that it was happening. Surprise failures are the worst kind.

[Wytnucls]

What concerns me is that these batteries failing took out a large part of the avionics, and there didn't seem to be any warning that it was happening. Surprise failures are the worst kind.

I am not aware of any part of the avionics sytem failing during the ANA battery incident. Could you quote your sources please.

"On Wednesday, ANA's flight NH 692 left Yamaguchi Ube in western Japan at 08:10 local time (23:10 GMT) and headed for Tokyo's Haneda airport.
Earlier reports that smoke was seen in the cockpit were inaccurate, ANA said. The pilots saw a warning on their computer screen telling them there was smoke inside one of the electrical compartments, the airline said. The source of the smoke is not yet known.
The pilots also received a warning that there was a fault in the battery system. ANA said the battery in the forward cargo hold was the same type as the one involved in a fire on another Dreamliner at a US airport last week.
The ANA flight landed at Takamatsu airport at 08:47 on Wednesday after the pilot saw an error message in the cockpit.
"There was a battery alert in the cockpit and there was an odd smell detected in the cockpit and cabin, and [the pilot] decided to make an emergency landing," said Osamu Shinobe, an ANA vice president, at a news conference.'

[r90s]

Boeing battery solution may keep 787 grounded until 2014

http://news.cnet.com/8301-11386_3-57566066-76/boeing-battery-solution-may-keep-787-grounded-until-2014/

Dear... Dear...

[TerraHertz]

So it's a mystery why the Li-Ion battery pack caught fire. OK, reasonable.

And then, surprise.... I just now discovered this:
  http://shkrobius.livejournal.com/398842.html
  On Ignorance. Aka "We don't know why Li-Ion batteries work.

Bloody hell. I had just assumed someone knew, and left it at that. But apparently it's also a mystery why they work normally (when not catching fire.)

Great.

[amyk]

So it's a mystery why the Li-Ion battery pack caught fire. OK, reasonable.

And then, surprise.... I just now discovered this:
  http://shkrobius.livejournal.com/398842.html
  On Ignorance. Aka "We don't know why Li-Ion batteries work.

Bloody hell. I had just assumed someone knew, and left it at that. But apparently it's also a mystery why they work normally (when not catching fire.)

Great.

There have been entire books written about that, so I don't think it's fair to say "we know nothing"; better to say that we have a pretty good idea of it, and just as we don't know what exactly an electron is, it doesn't stop us from engineering electronics.

[tom66]

I'm sure they could always switch to lead acid or NiCd in the interim?

[EEVblog]

It doesn't really seem like a safety issue though. For a system this big, I can thing of much worse things to go wrong.

A fire on a plane is one of the worst things that can happen, it's a huge safety issue!

Dave.

[PA0PBZ]

It's not the batteries?

http://www.bbc.co.uk/news/business-21230940

[Eliminateur]

A fire on a plane is one of the worst things that can happen, it's a huge safety issue!
Dave.

snakes on a plane is worst

[tom66]

Once the battery reaches a certain temperature, it can start self-heating with potentially disastrous results.

The units are also seen as especially vulnerable to problems and leaks of battery fluid. Once the problems start, the fluid is prone to ignite.

Never heard of a li-ion battery containing any sort of fluid?!

[IanB]

Never heard of a li-ion battery containing any sort of fluid?!

The electrolyte. In lithium ion batteries the electrolyte is a flammable organic solvent. That's why the batteries burn so nicely. Most batteries contain a water based electrolyte and don't catch fire.

[SoftwareSamurai]

It's not the batteries?

http://www.bbc.co.uk/news/business-21230940

Ok, now I think they're just guessing. 

[TerraHertz]

The heading "Airline safety inspectors have found no faults with the battery used on Boeing's 787 Dreamliner, Japan's transport ministry has said." juxtaposed with a photo of the charred mess that was the battery unit, is quite bizarre.

Almost dreamlike. Dreamliner-like...

Now might be a good time to buy puts on Boeing. Or perhaps too late.

[EEVblog]

Heaps of info and photos here:
http://aviationtroubleshooting.blogspot.com.au/

Dave.

[tom66]

Never heard of a li-ion battery containing any sort of fluid?!

The electrolyte. In lithium ion batteries the electrolyte is a flammable organic solvent. That's why the batteries burn so nicely. Most batteries contain a water based electrolyte and don't catch fire.

Well, I've punctured a li-poly pack (not pretty... luckily I had a bucket of water nearby!) and it's just a thick kind of paste/solid stuff in there. It's certainly not liquid.  I don't know if li-ion are much different.

[IanB]

Well, I've punctured a li-poly pack (not pretty... luckily I had a bucket of water nearby!) and it's just a thick kind of paste/solid stuff in there. It's certainly not liquid.  I don't know if li-ion are much different.

OK, paste, but it's wet or damp and it burns very well, especially if you heat it up.

In most modern batteries the liquid electrolyte is absorbed into some kind of matrix like cloth or paper or in the case of li-poly it's a kind of polymer gel. There has to be liquid in there of some kind for the ions to move and the battery to work, although the formulation is often a "starved electrolyte" kind which is bordering on the dry.

[TerraHertz]

Incidentally, for anything aircraft-related, there's always a thread somewhere at http://www.pprune.org/rumours-news-13/ (professional pilots rumor network).
Currently:
 http://www.pprune.org/rumours-news/505455-faa-grounds-787s.html
 http://www.pprune.org/rumours-news/505348-ana-787-makes-emergency-landing-due-battery-fire-warning.html

Prepare for information overload, if you enter.

[EEVblog]

Wow, this gives you some idea of the backups upon backups in the 787:
http://boardingarea.com/blogs/viewfromthewing/2012/04/21/the-boeing-787-from-a-pilots-perspective/

Dave.

[r90s]

Incidentally, for anything aircraft-related, there's always a thread somewhere at http://www.pprune.org/rumours-news-13/ (professional pilots rumor network).
Currently:
 http://www.pprune.org/rumours-news/505455-faa-grounds-787s.html
 http://www.pprune.org/rumours-news/505348-ana-787-makes-emergency-landing-due-battery-fire-warning.html

Prepare for information overload, if you enter.

I get the page, and the connection is reset right away, deleting the page!