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edsparks3
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Iron
Re: Were the Boeing 787 Batteries Cooled Properly
edsparks3   1/28/2013 5:10:05 PM
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Ougassing should have been observed during tests.  True, low atmospheric pressure might accelerate outgassing but the atmospheric pressure inside a (pressurized) commercial aircraft cabin is generally in the range of normal. 

I also think vibration could be the culprit.  (see my comment, above).  

Charles Murray
User Rank
Blogger
Re: Design Decisions
Charles Murray   1/28/2013 5:06:41 PM
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That's a scary thought, Bill. It's not hard to imagine Boeing deliberately choosing cobalt oxide for the higher energy density. That's its chief advantage over other lithium-ion chemistries and it's the reason many engineers choose that chemistry. But as for their alleged lack of a cooling system: It's anybody's guess. I think a lot of engineers are still climbing the learning curve when it comes to all the lithium-ion chemistries.

edsparks3
User Rank
Iron
Overheating?
edsparks3   1/28/2013 4:57:15 PM
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I can't believe Boeing would use a battery design that was not so carefully bench tested that there was absolutely no way it could overheat no matter what happened to the charging circuit and no matter how little cooling was available.    

On the other hand it is quite possible that due to vibration in the aircraft, the electrodes might go into a vibrational resonance allowing a couple to touch each other and cause an internal short.  This could be difficult - but not impossible - to simulate on the bench.  

But it might answer a lot of questions. 

 

Charles Murray
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Blogger
Re: Were the Boeing 787 Batteries Cooled Properly
Charles Murray   1/28/2013 4:53:43 PM
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Very good point, Paul. Elton Cairns of the University of California agrees with you. He told us that the higher, colder altitudes were a detriment, not an advantage in this situation. Cairns, by the way, should know: He designed the PEM fuel cells for the Gemini spaceflights in the 1960s.

apresher
User Rank
Blogger
Boeing 787
apresher   1/28/2013 4:51:29 PM
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Given the importance of this issue to Boeing, I would be shocked if it kept the 787 down until 2014.  That would be a major setback to a very high profile program.  But I also think their engineers will also be very careful in avoiding missteps in implementing a solution to this problem. Not an easy thing to have the world watching while you solve a complex technical issue.

Elizabeth M
User Rank
Blogger
Re: Batteries, not composites
Elizabeth M   1/28/2013 4:50:32 PM
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Yes, Ann, good point! At least it seems like that part of the design is sound.

Elizabeth M
User Rank
Blogger
Re: Let's hope they get the chemistry right
Elizabeth M   1/28/2013 4:50:00 PM
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Well, good! If that's the way it has to be, that's the way it has to be. Better to wait until the design is completely safe to fly the fleet than risk human life.

Charles Murray
User Rank
Blogger
Re: Let's hope they get the chemistry right
Charles Murray   1/28/2013 4:47:02 PM
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They will get it right eventually, Liz. But it could take a while. Over the weekend, CNET published a story in which they, too, interviewed Donald Sadoway of MIT. Sadoway told them that the problems could keep the 787 fleet grounded until 2014.

http://news.cnet.com/8301-11386_3-57566066-76/boeing-battery-solution-may-keep-787-grounded-until-2014/

Ann R. Thryft
User Rank
Blogger
Batteries, not composites
Ann R. Thryft   1/28/2013 4:25:02 PM
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At least no one's blaming this on the plane's use of carbon composites.

Elizabeth M
User Rank
Blogger
Let's hope they get the chemistry right
Elizabeth M   1/28/2013 2:52:53 PM
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If this is true, then it's a bit scary to think this could happen again. Let's hope engineers get the battery chemistry right next time so something like this doesn't happen again and cause an even more dangerous situation.

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