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The investigation is ongoing

The National Transportation Safety Board announced over the weekend that x-rays and CT scans of the lithium-ion battery pack that caught fire in a Boeing 787 Dreamliner in Boston recently was not overcharged. The battery in question powered the plane’s auxiliary power unit and the investigators have disassembled the battery and are still investigating some of the individual battery cells.

The battery fire has led airlines to stop flying the 787 planes around the world. The NTSB investigators have also said that they have examined several other components from the aircraft including battery management circuit boards and associated bundles of wire. The investigators also intend to continue testing components such as the battery charger and battery management unit.

The investigators have announced that the plane's flight data recorder indicates that the battery never exceeded its design voltage of 32 volts. The FAA issued a directive last week that the Boeing 787 Dreamliner should not fly until any problems with the battery packs are resolved.
 
Boeing has announced that it will halt deliveries of the 787 to customers while it works with the FAA to solve the battery issues. The batteries at the center of the investigation are lithium-ion units manufactured in Japan by GS Yusana under a subcontract to a company called Thales.

Source: CNN



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IEEE's theory
By gamerk2 on 1/21/2013 2:51:23 PM , Rating: 3
http://spectrum.ieee.org/tech-talk/aerospace/aviat...

quote:
It seems that the batteries heated up in a self-accelerating pattern called thermal runaway. Heat from the production of electricity speeds up the production of electricity, and… you’re off. This sort of things happens in a variety of reactions, not just in batteries, let alone the Li-ion kind. But thermal runaway is particularly grave in Li-ion batteries because they pack a lot more power than the tried-and-true metal-hydride ones, not to speak of Ye Olde lead-acid.


So the IEEE is theorizing that thermals could be to blame. Makes more sense then most theories here.




RE: IEEE's theory
By drycrust3 on 1/22/2013 10:38:02 AM , Rating: 2
The problem with the thermal theory is the cells at the end of the battery box seem to be the ones that have collapsed, which suggests they were the ones that actually failed, not the ones in the middle, which is where it would be hardest to dissipate heat.


RE: IEEE's theory
By puplan on 1/22/2013 3:05:11 PM , Rating: 2
Not necessarily. It depends on battery surrounding (airflow, contact with heat dissipating surfaces, etc.).


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