FAA Reports Heat In Cargo Holds Can Ignite Laptop Batteries

SpuriousLogic writes "US aviation officials are warning air carriers that new research shows lithium batteries are sensitive to heat and can ignite in-flight if transported in cargo compartments that get too hot. The Federal Aviation Administration also acknowledged publicly for the first time Friday that a United Parcel Service 747-400 plane that crashed in Dubai last month killing both pilots was carrying a large quantity of lithium batteries. Since the early 1990s, there have been dozens of incidents of batteries igniting in flight. But it has not been known what triggered many of the fires. FAA now says recent research has identified heat as the trigger and is offering air carriers advice on how to reduce the risk of fire."

Comments

Theory only

[SuperKendall]

In reality, a checked laptop has never actually made it as far as the cargo hold.

Obligatory XKCD

[Mad Merlin]

Witty on topic text here.

Re:Last time I looked

[mysidia]

Those are not necessarily conflicting ideas... if the temp in the cargo compartment is not controlled, it might be possible for it to get both extremely hot, or extremely cold at times, depending on local weather, whether the plane is on the ground or in flight, etc.

I imagine Lithium isn't the only thing that might catch on fire in extreme heat, however. Many electronic devices have "operating temperature ranges" and "storage temperature ranges"; although I suppose the airline doesn't care much if they break someone's checked iPod or computer due to letting the cargo temp be too extreme -- it's not until risk of fire, that they become more concerned, and think about banning anything containing Lithium batteries in checked luggage, due to the hazard,

RTFA?

[nmb3000]

Wow, so apparently TFS == TFA (which in turn is nothing but a copypasta of an AP release from earlier today. Is there really no more information on this? For example, how hot is too hot? My laptop gets pretty freaking hot sometimes and I'd guess a fair bit of that heat finds its way into the battery.

Doing some quick looking, I came across a study which exposed lithium batteries to fire and heat (PDF). On page 32-34 it says (paraphrased):

- Heated cells vent flammable electrolyte gas
- Cells begin venting at approx 470-500 Deg F
- The electrolyte gas occasionally exploded
due to hot surface ignition
- Cells produce a pressure pulse when venting
- As little as four cells can raise the pressure in a
sealed 10m cubed chamber by one psi.

Kind of interesting. It looks like I probably don't need to worry about my laptop's head igniting the battery, but it does sound like either some batteries are a lot more susceptible to heat, or airplane cargo compartments get really hot. I would guess a lot of other stuff doesn't like being stored at those kinds of temperatures either. A quick look indicates most plastics melt at about 300-450 degrees F. In fact, ABS plastic (usually used in laptop battery enclosures) melts even lower at 221 degrees F.

~500 degrees F is hot.

So that is what happened to my batteries...

[Brett Johnson]

Several months ago, on a flight from Virginia to California, a zip-lock bag containing spare batteries for my phone and camera and several power&usb cables "disappeared" from my luggage. At first I thought I had left it behind, but that turned out not to be the case. A couple of months later, I had a nearly identical zip-lock bag in my carry-on (sans the camera battery, which I have not yet replaced). I was pulled aside for "extra scrutiny" specifically because of this bag. The TSA agent removed it, re-ran my luggage, and returned it to me. I can only deduce that the TSA "stole" my batteries and cables on the earlier journey, because nothing looks more like a bomb that a Nokia cell phone battery and a USB cable.

TFA Says nothing about laptop batteries

[Rosyna]

Metal Lithium batteries!=Lithium-Ion batteries used in laptops. Metal Lithium batteries are too dangerous to be used in laptops.

Re:TFA Says nothing about laptop batteries

[tweak13]

The summary is basically a complete failure to understand the issue. Actual advisory here.

Basically what this says is, a fire in a cargo compartment could easily heat lithium batteries to the point that they cause explosions and large secondary fires. Also, the fire suppressant commonly used in cargo bays may not control a lithium fire. Thirdly, shorted lithium batteries may get so hot that they ignite other materials around them, even if they don't catch fire themselves. Lithium-Ion batteries are also mentioned, basically restating the above but suggesting that existing fire suppression can more easily control a fire from a lithium-ion cell.

In the end, the recommendation is to change reporting rules so that lithium batteries in cargo must be reported to the pilot in command. Effort should be made to carry them in cargo bays with sufficient fire extinguisher capability. Also mentioned is storing them in containers designed to keep fire or explosion contained, and that existing containers will not do this.

It is even specifically noted that this advisory applies to bulk shipments and does not include batteries brought aboard by passengers.

Re:Last time I looked

[Flying Weezel]

it depends on which cargo hold your stuff is put in on an airplane. On my aircraft, the forward hold is heated & pressurized, and the aft hold is not.

here's how the bins (as we call them) are pressurized/heated. the air that comes out of the packs is routed through the cabin, then flows through the cargo bin before being dumped overboard through the pressurization valve. so while the bin is heated, there is no direct control of the heat like the cabin. we have charts in our manuals that will tell us the temp of the bins based on the outside air temp, so we can tell whether or not its safe to put Fido in the cargo, but otherwise we have no direct way of monitoring the cargo compartment temp.

Re:Last time I looked

[dgatwood]

How hot are we talking about? The safe maximum operating temperature for discharging a Lithium ion battery is typically 140 degrees Fahrenheit. There's no place on Earth that gets that hot naturally....

The notion that heat in cargo holds might ignite laptop batteries is patently absurd unless the cargo hold is on fire. It's more accurate to say that heat from an actively failing battery can start nearby cells on fire, which is a great big "duh".

Lithium ion battery fires are usually caused by dendritic growth inside the cell. There's no good way to determine when this might occur short of scanning electron microscopy, and there is no safe temperature at which this is not a problem....

The only time heat is a factor in Lithium cell failure is typically during a charge cycle (or occasionally during a very fast discharge cycle), when temperatures shoot way up into the mid 100s Fahrenheit. If they go way outside that range, they can go through thermal runaway.

That said, the charge circuits in the battery packs normally make this impossible unless a cell is defective. They shut down in such a way that the pack cannot be charged if the cell voltage drops below a minimum threshold because the charge current required would be high enough to pose a fire risk. Similarly, they disable charging above a maximum threshold to keep the batteries from becoming overcharged.

In short, if these things are burning up in flight, the cells were defective to begin with, period, and odds are good that they were improperly charged, too. There's just no way the cargo hold of an airplane gets hot enough to be a problem unless one of the cells shorts out internally, at which point the temperature really doesn't matter much anyway.