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Elon Musk  (Source:
He offered his help to Boeing, but the company declined

Boeing's 787 Dreamliner jet has had a lot of troubles lately -- namely with its batteries -- and the last person the aerospace company likely wanted advice from was competitor Elon Musk.

Musk, the CEO of automaker Tesla and private space transport company SpaceX, recently told Flightglobal that the 787 Dreamliner's batteries are "inherently unsafe." His company SpaceX competes with the Boeing/Lockheed Martin partnership, United Launch Alliance, in the aerospace sector.

"Unfortunately, the pack architecture supplied to Boeing is inherently unsafe," said Musk.
"Large cells without enough space between them to isolate against the cell-to-cell thermal domino effect means it is simply a matter of time before there are more incidents of this nature. Moreover, when thermal runaway occurs with a big cell, a proportionately larger amount of energy is released and it is very difficult to prevent that energy from then heating up the neighboring cells and causing a domino effect that results in the entire pack catching fire."

However, Mike Sinnett, Boeing's 787 chief project engineer, defended the design and development of the batteries.

"I design a cell to not fail and then assume it will and then ask the next 'what-if' questions," said Sinnett. "And then I design the batteries that if there is a failure of one cell it won't propagate to another. And then I assume that I am wrong and that it will propagate to another and then I design the enclosure and the redundancy of the equipment to assume that all the cells are involved and the airplane needs to be able to play through that."

Musk's Tesla uses batteries fueled by lithium cobalt oxide, which is what Boeing uses for the 787. Musk understands that these batteries have highly flammable tendencies, and even offered his help to Boeing in its construction, but Boeing declined.

"They [Boeing] believe they have this under control, although I think there is a fundamental safety issue with the architecture of a pack with large cells," said Musk. "It is much harder to maintain an even temperature in a large cell, as the distance from the center of the cell to the edge is much greater, which increases the risk of thermal runaway."

In a recent report by The New York Times, it was discovered that Boeing knew about the battery fire issues in the 787 before this month's problems occurred, which grounded the jets in the U.S., Japan and India.

The report said that Japanese airline All Nippon Airways (ANA) replaced 10 787 batteries from May to December of 2012. Reasons included an unexpectedly low charge in the main battery, batteries that failed to start normally and one battery showing an error reading.

Japan Airline (JAL) also had "several cases" where it had to replace the 787's batteries before the issues that occurred this month, but it didn't disclose an exact number.

The airlines said they reported the incidents' to Boeing, but Boeing felt they didn't need to alert safety regulators because it was not considered a safety issue, but rather "within the scope of regular maintenance" carried out by airline crews.

It was also recently discovered that the Japanese government loosened safety regulations for the 787 Dreamliner back in 2008 in an effort to speed up the aircraft's deployment within the country.

Source: Flightglobal

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RE: Me too
By othercents on 1/30/2013 3:38:58 PM , Rating: 3
You also have other well know battery consultants saying the same things.

“As the size of the cell increases, the chance of something happening increases because you have an increased amount of material being exposed” says Dr. K.M. Abraham. “[Lithium-ion batteries] are not as forgiving as far as design and construction are concerned. If you have quality control issues, it can be very bad.”

Dr. Abraham is a battery consultant and professor at Northeastern University in Boston and has been researching lithium-ion batteries since 1976.

There is still an option for overcharging a single cell within one of the batteries even if the battery never hit peak charge.

RE: Me too
By FaaR on 1/31/2013 5:46:41 AM , Rating: 1
There is still an option for overcharging a single cell within one of the batteries even if the battery never hit peak charge.

...Possibly, yes. As in, anything can happen. However, Li-ion batteries should have on-board electronics to control and measure the charging of each individual cell, to prevent just what you describe. Batteries in modern laptop computers and tablets work this way for example.

It's possible this regulation hardware failed somehow, but if that can happen and the battery can still be charged without any monitoring safeties then someone screwed up.

RE: Me too
By othercents on 1/31/2013 8:25:19 AM , Rating: 4
However, Li-ion batteries should have on-board electronics to control and measure the charging of each individual cell, to prevent just what you describe.

No they don't since a single Li-ion battery consists of multiple cells with insulation between them all wired to the battery terminal. The electronics are what control the charge on the battery (or in the case of the 787, 8 batteries), but not individual cells within the battery. It is very possible for a single cell to overcharge while the battery as a whole never hits peak. This is best illustrated from GSYuasa design spec.

You can also read more about what Dr Abraham has to say about overcharging a single cell within a Li-ion battery here:


RE: Me too
By DockScience on 2/2/2013 4:35:21 PM , Rating: 2
Musk is right on target, A WELL designed high power lithium battery WILL have monitoring of charge/discharge of individual cells. And in a fire critical installation, they will also have heat removal system capable of removing the heat to stop a thermal runaway, preventing catastrophic failure/rupture and solvent fires.

The question is whether or not the 787 battery is such a well designed battery, or is lacking.

I don't see heat pipes, liquid exchangers or other beefy heat removal devices in the pictures... and that's not a good sign for a battery which can withstand a thermal runaway initiation.

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