Blog Archives

News Bite: Boeing Continues to Gamble with Lithium Batteries in the Dreamliner

boeing_batteryPlease see “JAL reports problem with 787 battery on Helsinki-Tokyo flight,” 9 Nov 2013 Reuters, and “Battery Problems on Boeing’s 787 Dreamliner Are Back” by Meghan Foley, 11 Nov 2013 WallStCheatSheet

As mentioned previously (e.g., “Boeing’s Fix for its Flaming Lithium Batteries: Is There A Fatal Flaw?“), until Boeing digs down to the root cause of their lithium battery problems, they — and those who fly on the Dreamliner —  will continue to be exposed to undefined risk.

(Note: Boeing provided a report, “Certification of 787 Battery Solution,” back in April, which lists “improvements” and “enhancements,” but makes no mention of a root cause.)


MicroViews: Electric Vehicles Are Not Greener and Cleaner / Dreamliner Batteries Still Misbehaving? / Robot Boogie Time

pollutingRecommended Reading: “Unclean at Any Speed
“Electric cars don’t solve the automobile’s environmental problems,” by Ozzie Zehner, 30 June 2013 IEEE Spectrum. A standout example of scientific journalism. Mr. Zehner provides a remarkably thorough and balanced review of the overall relative pollution impact of electric vehicles.

Is The Boeing Dreamliner Lithium Battery Issue Really Solved?
From “Technical glitches delay two Dreamliner flights from Poland,” 4 July 2013, Reuters:

787dreamliner“A flight from Warsaw to Chicago that was scheduled to fly on Wednesday was canceled because the aircraft had “problems with the power supply…” “The spokeswoman would not say if the latest technical problems were related to over-heating batteries which forced the grounding of all Dreamliners for over three months.”

The Robots Are Coming! The Robots Are Coming!
And wow, can they dance!

Boeing Says Flaming Battery is Being Fixed But Doesn’t Know Why

human154It sounds like something from The Onion: “Boeing on Monday admitted it may never be established why batteries failed on two of its high-tech Dreamliner aircraft, as work began to fix the safety problem that grounded the company’s wide-body passenger jet.”
-from “Boeing in the dark over 787 battery fires,” by Andrew Parker, 22 April 2013 Financial Times

Boeing’s Flaming Batteries Fixed? Where’s The Proof?

boeing2“Boeing’s fix includes more insulation between each of the eight cells in the batteries. The batteries will also be encased in a new steel box designed to contain any fire and vent possible smoke or hazardous gases out of the planes.

“…both the F.A.A. administrator, Michael P. Huerta, and Transportation Secretary Ray LaHood said they were are satisfied that the proposed changes would eliminate concerns that the plane’s two lithium-ion batteries could erupt in smoke or fire.”
-“F.A.A. Endorses Boeing Remedy for 787 Battery” by C. Drew and J. Mouawad, 19 April 2013 New York Times

Conspicuously absent from this pronouncement is a definitive identification of the root cause of the lithium battery fires. Therefore Boeing, the FAA, and the Department of Transportation are all guessing that the stated modifications will fix the problem. I hope they are correct. But if they are it will be a matter of luck, not engineering diligence. The dissembling of the FAA and Department of Transportation are clearly evident in their own words: they say that they are “…satisfied that the proposed changes would eliminate concerns that the plane’s two lithium-ion batteries could erupt in smoke or fire.” If they are so satisfied, then why is it necessary to have a steel box to contain a fire? If they are so satisfied, then why did they not provide the supporting evidence to support their conclusions?

Also, Boeing and these government agencies have touted a few test flights as being of particular significance in proving the safety of the batteries. This is nonsense. The battery fires are low probability events, occurring only once for thousands of hours of operation. This implies that there are subtle variables in the battery construction, chemistry, and/or operation, which when combined worst case will cause the batteries to overheat. This combination may only occur for a small number of manufactured batteries, and fires may occur only when those particular batteries are exposed to a worst case combination of stresses (temperature, charge currents, etc.).

Therefore a handful of test flights, of a few dozen hours or so total, are not nearly sufficient to empirically identify a low-probability event. The identification of such an event would require hundred or even thousands of test flights, which is obviously not practical. Therefore the only alternative is an investigation that drills down and positively identifies the true underlying failure mechanism (as recommended here: Flying the Flaming Skies: Should You Trust the Boeing Dreamliner?“). It is my opinion that this has not been done, because if it had, this knowledge would be trumpeted by Boeing.

I’m not flying the Boeing Dreamliner until I see the evidence that supports the optimistic conclusions of Boeing, the FAA, and the Department of Transportation.

-Ed Walker

Flaming Lithium Batteries versus Profits: Who Wins?

CellPhoneFire“The unfortunate reality is that lithium-ion batteries were not ready for prime time four years ago and they’re not ready for prime time today.”
-from “Are EV Dreams Going Up In Smoke?” by John Petersen, 28 Mar 2013, Seeking Alpha

Despite claims that lithium battery technology is improving, lithium batteries continue to catch on fire. See the article above for some recent Mitsubishi examples.

The continued widespread use of a product that poses a serious and thus far unresolvable safety hazard is apparently based on the unfortunate business practice of balancing the costs of jury awards against the competitive advantage of using a dangerous product (lithium batteries have smaller size/weight for energy stored, compared to much safer types). Is there a CEO out there who is willing to forfeit some profits by discontinuing the use of lithium batteries? If so, please speak up.

-Ed Walker

Boeing’s Flaming Battery Fix: Time to Slow Down?

787dreamlinerJust a quick note for those following this fascinating story.

Michael Sinnett, Boeing’s chief project engineer, said in a recent briefing that “Boeing is redesigning its batteries to ensure a fire isn’t possible. Among the new features will be a fire-resistant stainless steel case that will prevent oxygen from reaching the cells so fire can’t erupt.” (from “NTSB Contradicts Boeing Claim of No Fire in 787 Battery,” by Alan Levin , 15 Mar 2013 Bloomberg).

The problem with that statement is that once a lithium battery is heated sufficiently, it releases its own oxygen to fuel continued burning/explosion. That’s why lithium fires are extremely difficult to extinguish, and why an outer case, although it may keep a fire from spreading, will not prevent a fire from erupting.

-Ed Walker

Boeing’s Fix for its Flaming Lithium Batteries: Is There A Fatal Flaw?

dubaiupsplanecrash“Boeing Co. is confident that proposed changes to the 787 Dreamliner will provide a permanent solution to battery problems that grounded its newest jet, a senior executive said Monday.” –Reuters, 11 March 2013

The reported changes include “adding ceramic insulation between the cells of the battery and a stronger stainless steel box with a venting tube to contain a fire and expel fumes from the aircraft.” –Reuters, Alwyn Scott and Tim Hepher and Peter Henderson, 5 Mar 2013

Why is Boeing confident? This is a mystery because, based on available published data, it does not appear that Boeing has positively determined the root cause of the battery fires. Furthermore, as for all safety-critical applications, the certainty of the cause should be determined beyond a reasonable doubt. This stringent requirement would be certified by a panel of independent experts of unquestioned expertise and integrity, who have no financial interest in the outcome of their review.

Without positive identification of the root cause, Boeing may be indulging in a logical fallacy that I have seen employed before, with very bad results. The fallacy is in trying to fix what is assumed to be the problem (e.g. inadequate thermal insulation between battery cells). But what if the assumption is wrong? If so, the “fix” could be ineffective, or even make things worse. For example, improving cell insulation will trap more heat within the cells, raising the cell temperature. If the true root cause is related to higher cell temperature, the added insulation could make cell failure more likely, not less.

There are many other troubling scenarios that can be hypothesized, and the only way to disprove them is to dig in and find the true root cause, beyond a reasonable doubt (including rigorous validation as discussed here: “Flying the Flaming Skies: Should You Trust the Boeing Dreamliner?“)

-Ed Walker

P.S. A good review of the genesis of the Boeing battery problem can be found here: “NTSB report shows Boeing’s battery analysis fell short,” Dominic Gates, Seattle Times

Boeing’s Flaming Lithium Batteries: Was This A Risk Worth Taking?

boeing_batteryIn DACI’s 1st Quarter 2012 newsletter I predicted that a catastrophic safety event would eventually occur due to lithium batteries (please see “Li-Ion Battery Pack Hazards and our Psychic Prediction“). The recent fires in the initial flights of the new Boeing Dreamliner have come close to fulfilling that prophecy.

From “Detecting Lithium-Ion Cell Internal Faults In Real Time” (Celina Mikolajczak, John Harmon, Kevin White, Quinn Horn, and Ming Wu, in the Mar 1, 2010 issue of Power Electronics Technology) it is known that internal cell faults in lithium batteries can lead to thermal runaway, subsequently resulting in fires and/or explosions. Therefore the question arises: do the Boeing lithium batteries have an advanced internal construction that prevents cell faults, or mitigates thermal runaway in the event of a fault? If not, the Boeing team or vendor responsible for the battery system design is in big, big, trouble.

Although deficiencies in basic battery chemistry and/or construction appear to offer the best root cause hypothesis for the fires, there are also other possible factors. For example, it has been reported that perhaps the charging system malfunctioned, causing the batteries to overheat. However, a properly designed charger for an aircraft application would have fail-safe protection, preventing an overcharge. Plus, it was also reported that charging sensors did not detect an overvoltage. Although these factors sound reassuring, they are not sufficient to eliminate the charger from consideration. For example, one can hypothesize a charging waveform that contains spurious high frequency oscillations that create high rms charging currents. This would not necessarily result in overvoltage, but could result in overheating.

It is also possible that battery “cell defects” are nothing more than cell imbalances that vary according to production tolerances. In other words, the lithium battery, by its very nature, tends towards thermal runaway unless the internal cells are very tightly matched. This sensitivity would become more pronounced with a higher number of cells and higher mass, which would explain why no explosions have occurred in  small button-style batteries, but do occur in the larger batteries.

There are other scenarios, including the thorny possibility that some combination of conditions conspired to create the failure. And, of course, the root cause may be highly intermittent, making detection extremely difficult. Such hypotheses are undoubtedly being examined by the Boing engineers. I wish them well, and hope that they are allowed to perform their work calmly, methodically, and thoroughly.

Note: Because it may take quite a long time to conclusively establish a root cause, I would suggest that Boeing immediately begin planning to retrofit the lithium system with one containing battery types that have not shown the proclivity to explode; e.g. nickel metal-hydride, or sealed lead acid gel. Heavier, yes, but in this case safety and the economic timeline indicate that it would be wise to be prepared with a retrofit design.

(For some brief guidelines on design failure crisis management, please see Scenario #6: “Coping with Design Panic,” in The Design Analysis Handbook, Appendix A, “How to Survive an Engineering Project.”

-Ed Walker