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Problems with the Dreamliner battery

by Greg Bernhardt
Tags: 787, batteries, battery, dreamliner, lithium, power
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Greg Bernhardt
#1
Jan24-13, 07:13 PM
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Surprised there hasn't been a thread for this big topic. Any experts out there want to weigh in on what the problem is, how it can be fixed and what this means for Boeing?

As Boeing and airline officials sought to assure travelers of the overall safety of the world's newest jetliner, federal safety officials Thursday painted a graphic picture of a disaster averted, displaying the charred remnants of a battery that "spewed molten electrolytes" from its container shortly after landing in Boston earlier this month.
http://www.cnn.com/2013/01/24/travel...html?hpt=hp_t1
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nsaspook
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Jan24-13, 09:56 PM
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The thermite-style failure mode reactions are well know so I'm sure the calculation was made showing the frequency of it happening being very low. At least the means to handle it until burning out seems to be working.

http://www.fire.tc.faa.gov/pdf/syste...y_04112006.pdf
http://www.wpi.edu/Pubs/E-project/Av...PSCIQP2006.pdf
http://seattletimes.com/html/busines...tml?prmid=4939

To completely rule out any catastrophic high-energy fire or explosion that could result from overcharging a battery, Sinnett said, Boeing designed four independent systems to monitor and control the battery charge.

However, he conceded that if an internal cell shorts and overheats, “the electrolyte can catch on fire and that can self-sustain.”

“Something like that is very difficult to put out,” Sinnett said. “Because the electrolyte contains an oxidizer, fire suppressants just won’t work.”

Boeing’s design solution is to contain that outcome until the combusting battery cell or cells burn out.

“You have to assume it’s not going to go out,” Sinnett explained. “You have to assume that it’s going to go and that it’s going to expend all of its energy.
....
During testing of a prototype charging-system design in the 2006 incident, “the battery caught fire, exploded, and Securaplane’s entire administrative building burned to the ground,” according to a summary by the administrative law judge in a related employment lawsuit.
Ivan Seeking
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Jan25-13, 01:16 AM
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There have been many problems with the Dreamliner but this was expected. It represents, by all accounts that I've heard, the biggest change in the construction of commercial airliners since we started building them. Note that it doesn't even have an airframe by traditional standards. So none of this is surprising. And they have probably solved problems far more difficult than this along way a thousand times over before the craft was certified for flight.

Obviously everyone is anxious to get any remaining issues resolved but it seems to be a phenomenal aircraft. AFAIK, this and the previous delays are mainly PR and cash flow issues and not surprising from an engineering perspective.

AlephZero
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Jan25-13, 08:27 AM
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Problems with the Dreamliner battery

Quote Quote by Ivan Seeking View Post
It represents, by all accounts that I've heard, the biggest change in the construction of commercial airliners since we started building them.
Indeed, and the outcome is pretty much what you would expect from a project with so many unknowns - delivered years late, way over budget, and doesn't work.

Igmore all the BS public relations that "it's safe to fly". If anybody could come up with a creative argument that is it WAS safe to it was safe to fly, it would still be flying.

The FAA also has some backtracking to do, considering it agreed new regulations specifically to certify the new 787 electrical system. I'm not expecting any quick resolution for this.

Boeing have bet the farm on this one. The only good news here is, the 787 hasn't killed anybody .... yet.
Ivan Seeking
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Jan25-13, 12:48 PM
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Quote Quote by AlephZero View Post
Indeed, and the outcome is pretty much what you would expect from a project with so many unknowns - delivered years late, way over budget, and doesn't work.

Igmore all the BS public relations that "it's safe to fly". If anybody could come up with a creative argument that is it WAS safe to it was safe to fly, it would still be flying.

The FAA also has some backtracking to do, considering it agreed new regulations specifically to certify the new 787 electrical system. I'm not expecting any quick resolution for this.

Boeing have bet the farm on this one. The only good news here is, the 787 hasn't killed anybody .... yet.
Why so negative? An Airbus fan I presume? There are issues but internally I don't hear any concerns like this.

Of all the concerns that one might have for something this innovative, a battery problem seems pretty hard to worry about. There have been far bigger bumps along the way.
anorlunda
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Jan25-13, 03:56 PM
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The 787 has been in the news much after recent battery fires. In media aricles I found several references to a possible interaction between the battery and the 787's unique electric power distribution system.

What's so unique about the 787's electric power distribution system?

Can anyone please provide a link to an article about it?

Thanks.
berkeman
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Jan25-13, 05:52 PM
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Quote Quote by anorlunda View Post
The 787 has been in the news much after recent battery fires. In media aricles I found several references to a possible interaction between the battery and the 787's unique electric power distribution system.

What's so unique about the 787's electric power distribution system?

Can anyone please provide a link to an article about it?

Thanks.
This is the closest I've found so far, but it's not much help:

http://www.newairplane.com/787/desig...c-architecture

Click on the "Read More" button in the upper right. It only seems to be saying that there are more electrically operated items and fewer pneumatic/hydraulic items....
berkeman
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Jan25-13, 05:59 PM
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And this DesignNews interview with Boeing's lead engineer on the 787 seems to be saying the same things -- more electricity power devices (like air conditioning) and less pneumatics...

http://www.designnews.com/document.a...Layout=article

.
jim hardy
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Jan25-13, 06:19 PM
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Here's a 4 page description from Boeing.


http://boeing.com/commercial/aeromag...icle_02_1.html
Astronuc
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Jan25-13, 07:12 PM
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Quote Quote by anorlunda View Post
The 787 has been in the news much after recent battery fires. In media aricles I found several references to a possible interaction between the battery and the 787's unique electric power distribution system.

What's so unique about the 787's electric power distribution system?

Can anyone please provide a link to an article about it?

Thanks.
I think it is the objective to reduce mass, which means increased power density. The Li-batteries have a smaller mass, but apparently flammable electrolytes.

As far as I know, aircraft use electricity from generators driven from the jet engines. When the engines are shutdown and before the external power supply is connected, the batteries provide power. Some aircraft have small turbine powered auxilliary power units (APUs) in the tail.
russ_watters
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Jan25-13, 07:30 PM
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Similar threads merged.
AlephZero
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Jan25-13, 07:44 PM
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Quote Quote by Ivan Seeking View Post
Why so negative? An Airbus fan I presume? There are issues but internally I don't hear any concerns like this.
I tell it the way I see it. Both companies have made some pretty good aircraft, and some less good ones.

IMO some of the other 787 problems in the news (e.g. brake failure, fuel leak, cracked window) ARE in the "no big deal" category. You don't ground an aircraft type permanently worldwide because of stuff like that. But the 787 electrical system is in a different league - it's a totally new concept and covers far more functionality than on any previous commercial aircraft. If that doesn't work, the problems are big time, and could involve huge amounts of redesign work - including knock-on effects like redesigned engines.

There were some "11th hour" electrical problems with the flight test programme back in 2010, which caused more delays to entry into service. Unsurprisingly, there's not much in the public domain about what really happened back then, but sometimes stuff like that comes back to haunt you...

One measure of the seriousness of grounding an entire aircraft type is how rarely it happens. The last time was back in 1979 (the DC-10, following a crash).
nsaspook
#13
Jan25-13, 11:09 PM
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The Dreamliner uses Lithium cobalt oxide batteries. http://en.wikipedia.org/wiki/Lithium_cobalt_oxide

They have excellent power density but it's also the most susceptible lithium-ion to high energy thermal runaway events.
http://www.rev-electricbikekits.com....0Batteries.pdf
jim hardy
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Jan26-13, 11:46 AM
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spook - your link suggests a safer alternative battery?

http://en.wikipedia.org/wiki/Lithium...sphate_battery

at first glance one has to ask "why didn't they.... ?"

I have a strong opinion - some parts of machines should remain mechanical instead of electric. I won't own an automobile with electric steering or a computer between my foot and throttle & brakes.
Or a huge li-ion battery right under my butt. Some years back a small one in my pocket nearly set my pants afire.

old jim
nsaspook
#15
Jan26-13, 12:57 PM
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Quote Quote by jim hardy View Post
spook - your link suggests a safer alternative battery?

http://en.wikipedia.org/wiki/Lithium...sphate_battery

at first glance one has to ask "why didn't they.... ?"
I don't know why but lithium cobalt oxide batteries would not have been my choice for a large electrical system design where safety was a top priority. I've been designing an off-grid solar battery management system for a future retirement home and will never have them inside my house at the power levels I need for daily power storage (>5kWh daily). They just have really bad failure modes because IMO the lithium metal reaction is intrinsically unsafe as Boeing was using 4X redundancy in the BMS to prevent problems that are still happening.

Remember Dell?
http://www.telegraph.co.uk/news/1526...ry-recall.html
rollingstein
#16
Jan26-13, 02:15 PM
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Can they just work with the current battery and retrofit an emergency battery jettison system?
nsaspook
#17
Jan26-13, 02:38 PM
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Quote Quote by rollingstein View Post
Can they just work with the current battery and retrofit an emergency battery jettison system?
How about a passenger jettison system. http://en.wikipedia.org/wiki/File:B-...pe_Capsule.jpg
rollingstein
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Jan26-13, 02:41 PM
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Quote Quote by nsaspook View Post
How about a passenger jettison system. http://en.wikipedia.org/wiki/File:B-...pe_Capsule.jpg
Jettisioned Batteries don't need parachutes. Fire and forget.


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