Lithium-Ion Batteries Linked to Airplane Fires

smellsofbikes writes "The National Safety Transportation Board thinks it's possible that lithium-ion batteries caused a fire that destroyed a United Parcel Service airplane on Feb 8, 2006. The FAA already bans non-rechargeable lithium batteries from air shipment because aircraft don't carry fire suppression equipment capable of extinguishing lithium fires. The interesting thing is: these batteries aren't being used or charged, they're just being shipped: spontaneous battery combustion. Is this something that happens in the back of computer stores, or just on airplanes?"

Comments

Environmental stress

[morcheeba]

It's not just spontaneous, it's environmental stress. A cargo hold is a cold, low pressure, high vibration environment . This may be the first time a newly-made battery is exposed to these factors, causing infant mortality flaws in manufacture to become aparent. Even after the infant mortality portion of the bathtub curve, reliability calculations typically rate one hour of cargo flight time as worth 10-20 hours on the ground. That flight from china may be equal to 10 days on the ground.

Nope, it happens in plenty of places

[Anonymous Coward]

Flashlight geeks have been dealing with this issue for a while.

http://www.candlepowerforums.com/vb/showthread.php ?t=78843

http://www.candlepowerforums.com/vb/showthread.php ?t=124776

There have been several documented "venting with flames" of primary CR123A batteries. Rechargeables seem to be a lot more stable, occasional Dell laptop conflagarations notwithstanding.

Re:Nope, it happens in plenty of places

[dpaton.net]

A majority of CR123s aren't designed for contsant discharge at a relatively high rate. They are marketed to the photo market, where there are pulses of high power and long periods of very low draw. They do function at higher draws, but with reduced lifespan. This is hidden deep in the spec sheets, where the pulsed current recovery and discharge profile math is. I'm not terribly surprised that people have problems with lithium primary cells (NOT Li-po, Li-Ion, or any of the rechargable Li chemistries) in use for high current loads like the high power miniature flashlights out there like the Pelican M6 (the example cited in the second CandlePower link). The Xenon bulb version will suck the power out of a pair of CR123s in 1 hour. Calling the batteries 1300mAH (an average, according to Google), that means they're being loaded to about 1.3A each. That's a ~1C discharge rate. Most cells I found data sheets on didn't show a 1.3A discharge curve, instead showing a 1A curve or 1200mA pulse discharge measurement, using a 3s on / 7s off (30%) duty cycle. 10% can mean a lot in these cases. Odds are a lot of those cells are being used on the edge of or well past their design envelope. Beating up batteries like that can cause trouble, especially for cells that are fragile. Of course, not all are. The Energizer E2 photo lithium CR123 shows a capacity of 1.5AH and a 1000mA discharge life of 1.2 hours. It's probably the one used by Pelican to reach the rating of their flashlight, even if it looks like they did push the cells a little past their design limits.

Lithium primary cells generally do not have construction compatible with fast discharge. Often it can be gotten away with if the discharge is under 0.6C or is of a pulsed nature. Continuous discharge will kill them tho, a flaming, explosive kill.

Batteries have ever-increasing power densities, and deserve respect from designers. Just tossing 123s in is a BAD idea IMO. I was an engineer on a project where someone did just slap one in without consideration. When we put the test unit through its paces, blammo. Pulling 2A out of a 1.5A battery for 7 seconds is OK in NiCads and NiMH cells and even rechargable LiPoly prismatics if you know what you're doing. This was a dime store photo battery, and it went off like a small cannon after a few seconds.

People don't think about the design envelope for batteries as much as they should any more. It's unfortunate.

My US$0.02 as an engineer.

Re:squished?

[treeves]

That would be a plausible explanation if the battery contained elemental lithium. They don't. They contain compounds of Li.

Re:Too slow?

[cat6509]

It is the NTSB that researches things like this, not the FAA per se. They are very methodical and precise with their work. They are slow to publish thier findings, this doesn't mean they are slow to identify the cause, just very carefull that they have come to the correct conclusion. Check out the NTSB aircraft accident database, this contains detail over every aircraft accident reasearched by them for several decades ( 1962 ) http://www.ntsb.gov/ntsb/query.asp