Boeing 787 and Lithium Ion battery failure
Steve Taranovich - January 17, 2013
San Francisco Chronicle reported this morning that the Federal Aviation Administration grounded Boeing's new 787 Dreamliner Wednesday, January 16, after an All Nippon Airways 787 made an emergency landing at Takamatsu airport in Takamatsu, Japan. ANA said a cockpit message showed battery problems and a burning smell was detected in the cockpit and the cabin.
The 787 is the first airliner to make extensive use of lithium-ion batteries to help power its energy-hungry electrical systems. The batteries charge faster and can be better molded to space-saving shapes compared with other airplane batteries.
Investigators traced the fire to the lithium battery pack of the jet's auxiliary power unit. Photo: Stephan Savoia
This makes the second battery failure in only 10 days, so it became apparent that the FAA wouldn't be able to wait for completion of its safety review before taking action. An inspection of the All Nippon Airways 787 that made an emergency landing in western Japan found that electrolytes, a flammable battery fluid, had leaked from the plane's main lithium-ion battery. Investigators found burn marks around the damage. Japan's Kyodo News agency quoted transport ministry investigator Hideyo Kosugi as saying the liquid leaked through the electrical room floor to the outside of the aircraft.
The two incidents resulted in the release of flammable electrolytes, heat damage and smoke, the FAA confirmed. The release of battery fluid is especially concerning, safety experts said. The fluid is extremely corrosive, which means it can quickly damage electrical wiring and components.
The electrolyte fluid conducts electricity, so as it spreads it can short circuits, interfere with electrical signals and make control of the plane impossible for pilots and ignite fires.
The FAA will be doing an extensive investigation into the cause of this failure, but there are some alternative investigations going on in the industry for alternative electrolytes with less volatile properties.
In general, Organosilicon (OS) compounds are environmentally friendly, non-flammable, high temperature materials. These characteristics make OS materials well-suited for use as electrolytes. Companies like Silatronix are working in this area. It remains to be seen if the resulting cells will have the capabilities needed for a jetliner like the Boeing 787 however.
The Dept. of Defense has awarded grants to some companies to look into the development of non-flammable electrolytes for Lithium-Ion batteries also.
In October 2012, the Fire Protection Research Foundation (FPRF) completed an assessment of the hazards associated with Li-ion batteries related to storage of Li-ion batteries and fire protection. Fire Protection Engineering published an article that details that work.
Generally, the root causes of energetic cell and battery failures can be classified as:
- Thermal abuse (e.g., external heating);
- Mechanical abuse (e.g., denting, dropping);
- Electrical abuse (e.g., overcharge, external short circuit, over discharge);
- Poor cell electrochemical design (e.g., imbalance between positive and negative electrodes); and
- Internal cell faults associated with cell manufacturing defects (e.g., foreign metallic particles, poor electrode alignment).
More to come on this issue in the coming days
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