Fri Jan 18, 2013, 04:58 PM
Omaha Steve (46,536 posts)
Overcharged batteries eyed in Boeing 787 fires
By JOAN LOWY
WASHINGTON (AP) - It's likely that fires on two Boeing 787 Dreamliners were caused by overcharged lithium ion batteries, aviation safety and battery experts said Friday, pointing to developments in the investigation of the Boeing incidents as well as a battery fire in a business jet more than a year ago.
An investigator in Japan, where a 787 made an emergency landing earlier this week, said the charred insides of the plane's lithium ion battery show the battery received voltage in excess of its design limits.
The similarity of the burned battery from the All Nippon Airways flight to the burned battery in a Japan Airlines 787 that caught fire Jan. 7 while the jet was parked at Boston's Logan International Airport suggests a common cause, Japan transport ministry investigator Hideyo Kosugi said.
"If we compare data from the latest case here and that in the U.S., we can pretty much figure out what happened," Kosugi said.
FULL story at link.
Read more: http://apnews.excite.com/article/20130118/DA3SR3L80.html
5 replies, 1551 views
Overcharged batteries eyed in Boeing 787 fires (Original post)
|Omaha Steve||Jan 2013||OP|
|Leslie Valley||Jan 2013||#2|
Response to Omaha Steve (Original post)
Fri Jan 18, 2013, 05:28 PM
Leslie Valley (310 posts)
2. I recently shipped a laptop to my grandson stationed in Japan
and had to remove the lithium ion battery. He had to by one through the base exchange.
Seems someone at Boeing should have looked into this a little closer.
Response to Omaha Steve (Original post)
Fri Jan 18, 2013, 07:46 PM
Samba (39 posts)
"show the battery received voltage in excess of its design limits. "
PoP - and a fire. These batteries all have fancy electronics to ensure that no cell gets over charged or over discharged and to balance the charge of their various cells during charging. Overcharging causes swelling/bursting and ingredients in the electrolytes are fairly flammable. Over discharging ruins the battery - it won't last as long or hold as much as it should.
Cell phones, tablets, ipods, games and such use a single-cell - simple electronics and virtually no problems. It gets much fancier with multiple cells - like the 19-25v laptop batteries that caused problems a few years back - and the 300V electric/hybrid car batteries that have had problems since then.
Those same electronics should also prevent any excess voltage from ever reaching the battery. I'm guessing that the battery guys made them to spec for specified input voltage and left out a basic safety circuit that should be part of all such batteries to reject/shutdown in the case of bad voltage. Someone skimped on a double redundancy. Something outside the battery let thru an unsafe voltage, but the battery management system should always have its own voltage input limiting.
Air safety people hear 'lithium' and freak out - elemental pure lithium burns with air contact, explodes with water contact and eats aluminum which planes are made of. The stuff in lithium batteries (the rechargeable ones like this) don't have those issues but earlier non-rechargeable military batteries (there are many older types of lithium batteries) did require extreme precautions.
Nowadays its hard to transport Lithium Ion batteries by air - more in line with the "lithium - OMG" freak out than the actual flammability. The usual problem in transport is a package gets dissed - smashed such that battery terminals are forced to contact metal - a short circuit - and these batteries are so strong they can release hundreds of amperes heating the metal very hot - causing a fire and eventually the batteries electrolyte burns too. Not a true lithium fire but the responders hear 'Lithium" and they OMG!.
Response to Samba (Reply #4)
Sat Jan 19, 2013, 12:15 AM
MannyGoldstein (30,252 posts)
5. But why wasn't it caught during test?
Doubly scary: the design of critical circuitry was obviously quite flawes, and it wasn't picked up during testing.