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Investigation continues focusing on battery certification

The investigation into the fire that affected a Japanese Airlines Boeing 787 Dreamliner at Boston Logan Airport on January 7 has pinpointed the source of the fire. According to the NTSB, the JAL lithium-ion battery comprised of eight individual cells showed multiple signs of short-circuiting leading to a thermal runaway condition.

That thermal runaway condition then cascaded to other cells in the battery leading to the blaze. According to the NTSB, charred battery components indicated that the temperature inside the battery case exceeded 500°F. The focus of the investigation moving forward will now be on the design and certification requirements for the battery system.

"U.S. airlines carry about two million people through the skies safely every day, which has been achieved in large part through design redundancy and layers of defense," said Hersman. "Our task now is to see if enough - and appropriate - layers of defense and adequate checks were built into the design, certification and manufacturing of this battery."

Boeing 787 production line [Image Source: Boeing]

The investigation has ruled out mechanical impact damage to the battery and external short-circuiting. There were signs of deformation and electrical arcing on the battery case not related to the cause of the fire according to investigators. Boeing had tested the battery during the 787 certification process and found no evidence to support that this sort of fire within the battery pack could occur.

Boeing has issued a statement on the investigation update stating that it plans to remain committed to working with the NTSB and the FAA along with its customers to maintain a high level of safety. “The 787 was certified following a rigorous Boeing test program and an extensive certification program conducted by the FAA. We provided testing and analysis in support of the requirements of the FAA special conditions associated with the use of lithium ion batteries,” said Boeing’s Marc Birtel. “We are working collaboratively to address questions about our testing and compliance with certification standards, and we will not hesitate to make changes that lead to improved testing processes and products.”

Sources: Boeing, NTSB

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RE: propagation of fire to adjacent cells??
By protomech on 2/11/2013 2:40:58 PM , Rating: 2
Porsche and Lexus are still using NiMH for their 2013 models. The 2014 Porsche 918 will use lithium-ion batteries.

But yes. The automakers are increasingly switching to lithium-ion for cost, durability, and packaging reasons.

Proper safety design can mitigate (not eliminate) the risk of thermal runaway .. just like proper safety design can mitigate (not eliminate) the risk of gasoline fires.

RE: propagation of fire to adjacent cells??
By alpha754293 on 2/11/2013 11:29:17 PM , Rating: 2
I would have thought that with the latest Prius going to Li-ion that Lexus would have followed suit already.

The other big reason why the automakers are switching over to Li-ion: mass. There's a HUGE push from ALL of the OEMs to make the vehicle lighter in order to meet the upcoming fuel economy standards/requirements.

Well...if you mitigate it enough, it can EFFECTIVELY be eliminated. There are things that you can do that where you start looking at the failure modes and effects analysis and start to think of things of how you can almost entirely prevent that mode of failure. I don't think that I've heard of a case of the kind of Pinto gasoline fires now that they put the gas tank IN FRONT of the rear cradle.

In fact, people (safety, regulatory, engineers) are so paranoid about potential failures of the fuel systems that it is probably one of the safest and most robust systems that exists on a car today. It's borderline ridiculous, but people are so paranoid about it that they overengineer the crap out of it.

By protomech on 2/12/2013 2:08:19 AM , Rating: 2
The latest Prius is still NiMH (Prius, US Prius V, Prius C).

2015 Prius is rumored to go lithium-ion. Guessing Toyota wants to get the kinks worked out with the Prius+ and the plug-in Prius before they move their mainstream Prius to the new chemistry.

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