Posted on 02/12/2013 4:58:37 PM PST by rawhide
A fire that broke out last week in a Boeing 787 Dreamliner could have been hot enough to melt the carbon-fiber reinforced plastic that makes up the plane’s shell, according to the results of tests the Federal Aviation Administration performed last year.
In the FAA tests, which the agency performed at its site in Atlantic City a year after it certified the Dreamliner, the temperature of the battery fires reached as high as 2,000 degrees Fahrenheit. The plane’s polymer skin melts at 649 degrees, according to its manufacturer, Victrex Energy of West Conshohocken, Pa.
It also burns at high temperatures. In two lithium battery fire tests last year, temperatures peaked between 1,400 and 2,000 degrees, according to a report of the test results. Some of the battery cells exploded and landed more than 100 feet from the fire, and one of the fires burned for more than an hour.
A Boeing safety document from last year shows the location of the battery in a lower compartment near the plane’s tail section. The compartment, which is not protected by the plane’s fire-suppression system, contains key electrical systems. The battery, which powers the plane’s auxiliary power unit, is close to the plane’s fuselage.
In a separate test last year, the FAA exposed a section of the composite material to fire, and photos in the report show a result that looks like Swiss cheese. Jonas said that 400 degrees is enough to degrade the material. A fire as hot as those in the FAA tests would burn it away.
(Excerpt) Read more at mcclatchydc.com ...
Wood burns hotter than 649 degrees.
Building them into an airframe strikes me as far-fetched.
Lithium battery packs are protected by active circuitry that keeps them from self-destructing. These single-chip "smart power" devices track charge state, keeping it within proper bounds, and also monitor the temperature of the battery.
Some lithium batteries can be put into a dangerous situation by excessive discharge. No, they don't explode by being drained, but they can become dangerous on subsequent charge cycles once they have been deep-discharged.
Seems that there is an easy answer to this. There is a weight issue, but no more that a fat woman sitting in isle 23.
Instead of using the latest batteries, revert to nickle cadmium and ditch the Li-Ion.
Looks like the head of Boeing Engineering is on the accelerated list for early retirement.
This would be what is known as a “bad thing”.
About 1700 degrees. Not hot enough to melt copper in a house fire.
They could be considering the new, promising batteries based on thermite...
When does aluminum melt? What temperature?
When does aluminum melt? What temperature?
Some Chinese manufacturers were rumored to skimp on protective circuitry which may be one of the reasons lithium battery packs have been rumored to catch fire. Who is the manufacturer of the Boeing battery packs?
“I am thinking Boeing does not want to go there because it would be admitting they failed at engineering this battery.”
There is a reason why you can’t ship these things by air...
“Lithium battery packs are protected by active circuitry that keeps them from self-destructing.”
No there not. That is false. I have a 2 amp hour 36 volt battery for my bike. This battery will supply 300 amps if shorted (until it explodes). NO active circuitry is going to protect you from that. Period...
” I have a 2 amp hour 36 volt battery for my bike”
Sorry, typo...
20 amp hour battery
Depends on the alloy, some versions melt at 1220 deg F. However it loses structural strength and deform much lower temps.
Either way the burning batteries would melt the old fashion aluminum aircraft as well as this new one.
Wood doesn’t generally burn at 1700, its much lower at about 700-800 degrees. Its the plastics and other materials that raise the temp of a house fire.
Copper melts at 1980 degrees F.
I was wondering how a 2 ah battery could supply 300 amp bridged current. It wouldn’t be for very long!
My electric scooter has four 38 ah batteries (AGM) in series.
Regarding the lithium packs, none of my R/C packs have any integrated charge/discharge control circuitry, although the separate balancing chargers are fairly sophisticated. It is possible that in certain applications packs are supplied with integrated circuitry — maybe laptop packs or something like that? The LiFePO4 A123 cells used in tools do not, I am almost positive, and the packs built from similar cells used to replace the SLA batteries in motorcycles and other recreational vehicles do not.
Ali Babba Battery Boys, Inc.
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