Lithium ion batteries suspect in 787 fire

[Herm]

energy density 103 Wh/kg, typical for LiFePO4.. that is going to be one heavy dune buggie

 

[TonyWilliams]

energy density 103 Wh/kg, typical for LiFePO4.. that is going to be one heavy dune buggie

We pulled half the pack to do a manual bottom balance on the cells.... 900 pounds.

 

[TomT]

But the batteries themselves are made by GS Yuasa Corp and initial reports at least, seem to indicate that it was a battery issue and not a charging or control system issue...

http://online.wsj.com/article/SB10001424127887324624404578255302123044128.html" onclick="window.open(this.href);return false;

I suspect the Europeans, and in particular Airbus, will not make a big deal over this as the battery system on the 787 is provided by Thales, a primarily European electronic systems supplier.

 

[Stanton]

At this point, I tend to agree that it's a battery issue (not just control electronics), which doesn't bode well. I know someone from GS Yuasa Corp and he isn't very happy. Back to a previous point: whatever they have to do--including pulling/replacing batteries in the field/production--doesn't lend itself to a fast approval process. I actually feel bad for Boeing because I want the plane to do well, but I think someone made a bad engineering decision (whether it was based on cost or not).

 

[LTLFTcomposite]

IIRC there was a lot of pressure during the 787 program to keep the weight down, and at one point the targets weren't being met. Perhaps there was too much pressure applied in this area that tipped decisions to riskier technology. No doubt weight savings get scrutinized everywhere.

On a message board on one of the other articles someone posted that if the batteries had been a more conventional type they would have been 3X larger and 6X heavier (or maybe it was the other way around). This charred battery box is what, 2 cu ft? If these things aren't all that big to begin with, what are we talking about, the size/weight of a couple suitcases saved? I wonder if it would even be an option to take the weight/space hit of some older battery technology until this is better understood, to at least get the planes flying and resume deliveries. Or is the space not even there to put something bigger/heavier in? Or for that matter, even they wanted to switch to something else, how many months would it take to get the redesign certified?

 

[JRP3]

I believe these are the cells: http://www.s399157097.onlinehome.us/SpecSheets/LVP10-65.pdf
Seems odd that the specific energy for these LiCo cells is about the same as LiFePO4.
Worth noting that LiCo cells have been used for many years in satellites and rockets.
http://www.gsyuasa-lp.com/satellites-rockets-lithium-battery-markets

 

[Herm]

Yes, the energy density is not very high.. these are probably old rugged designs, very well tested and documented.

 

[JRP3]

Possible problem here....

Securaplane, a unit of Britain's Meggitt Plc, first began working on the charger in 2004, but suffered millions of dollars of damages in November 2006 after a lithium-ion battery used in testing exploded and sparked a fire that burned an administrative building to the ground.

http://biz.thestar.com.my/news/story.asp?file=/2013/1/21/business/20130121111701&sec=business

 

[dhanson865]

Exactly what are these batteries used for? To back up the power generation from the engines? That comes from bleed air? Or is it to start the APU?

The 787 uses "fly-by-wire" controls, rather than hydraulics (or cables and push rods going farther back in aircraft design). I believe that the batteries are used to back up the various control systems in case of generator failure.

Fly-by-wire is lighter than traditional mechanically linked controls but it takes some redundancy to have enough backups in case of an electrical system failure. As someone used to mechanical flight controls, fly-by-wire makes me uncomfortable! So I guess that dates me as an old guy.

You do realize that most modern cars are fly by wire in that they don't have a direct mechanical link to the throttle or steering?

Isn't the Leaf fly by wire?

I know my Prius is.

 

[Nubo]

You do realize that most modern cars are fly by wire in that they don't have a direct mechanical link to the throttle or steering?

Isn't the Leaf fly by wire?

I know my Prius is.

Last I checked there were no production cars without mechanical steering.

 

[surfingslovak]

Possible problem here....

Securaplane, a unit of Britain's Meggitt Plc, first began working on the charger in 2004, but suffered millions of dollars of damages in November 2006 after a lithium-ion battery used in testing exploded and sparked a fire that burned an administrative building to the ground.

http://biz.thestar.com.my/news/story.asp?file=/2013/1/21/business/20130121111701&sec=business

Thanks for posting. I know nothing beyond the superficial information one can glean from the media, but it would appear somewhat logical that the cells overheated due to the specific charge/discharge regimen used in the Dreamliner, and then burst into flames because of their relatively low thermal run-away threshold and insuffcient ventilation. There could be a systemic design problem at play, instead of a manufacturing defect.

 

[dhanson865]

You do realize that most modern cars are fly by wire in that they don't have a direct mechanical link to the throttle or steering?

Isn't the Leaf fly by wire?

I know my Prius is.

Last I checked there were no production cars without mechanical steering.

OK, technically its electrically assisted power steering.

But the part about the throttle is still accurate.

http://en.wikipedia.org/wiki/Drive_by_wire#Uses_In_Passenger_Cars" onclick="window.open(this.href);return false;

Electronic fuel injection metering in diesel and gasoline engines is now widely used. Electronic throttle control is also in widespread use for gasoline engine control. Purely electronic brake and steering systems have yet to find widespread application in passenger cars. [snip] Hybrid electric vehicles employ limited electronically controlled regenerative braking, but the standard hydraulic braking system is retained. The growth in sales of hybrid and electric vehicles is likely to become an enabling factor for drive-by-wire systems in the future cars because of the availability of high power electrical supplies required for the new electrical actuators.

So yeah no true drive by wire steering yet but many purists on the automotive boards complain about electric steering without acknowledging the remaining mechanical link.


http://en.wikipedia.org/wiki/Electronic_throttle_control" onclick="window.open(this.href);return false;

Electronic throttle control (ETC) is an automobile technology which connects the accelerator pedal to the throttle, replacing a mechanical linkage. Most automobiles already use a throttle position sensor (TPS) to provide input to traction control, antilock brakes, fuel injection, and other systems, but use a bowden cable to directly connect the pedal with the throttle. An ETC-equipped vehicle has no such cable.

http://www.aa1car.com/library/throttle-by-wire.htm" onclick="window.open(this.href);return false;
In 1988, BMW was the first vehicle manufacturer to offer electronic throttle control on its 7-Series cars. In 1997, Chevrolet opted for "Throttle Actuator Control" (TAC) on its C5 Corvette. Today, you will find electronic throttle control on the Ford Crown Vic, Focus, Five Hundred, Fusion and Mustang, Saturn ION and L-Series, Cadillac CTS, STS & XLR models, Toyota Camry and Prius, various Mercedes models, Nissan Maxima, Volkswagen Jetta and Passat, and many other cars

I can't find a current comprehensive list of cars with ETC but I know most any modern car has it instead of the cable going to a mechanical linkage. I'd be surpised if the Leaf used a mechanical linkage/cable for the accelerator pedal.

 

[Ingineer]

Throttle has been "by-wire" for many years now on most all cars, with no backup (though there is redundancy on most). On the Leaf, along with the accelerator-by-wire, it also has "brake by wire", but with a mechanical/hydraulic backup.

Brake-by-wire (also Brake-by-air) has been used for many years on heavy vehicles, such as trucks and trains, only in the last 10 years or so has it made it into cars.

The first cars with actual production steer-by-wire will be Nissan's Infiniti brand coming out within the year. While it's true steer-by-wire, it still does have a fail-safe mechanical backup.

Here's an article describing the new Nissan tech:
http://www.extremetech.com/electronics/138136-nissaninfiniti-steer-by-wire-one-step-closer-to-accident-avoiding-and-self-driving-cars" onclick="window.open(this.href);return false;

-Phil

 

[fotajoye]

http://www.bloomberg.com/news/2013-01-16/ana-s-boeing-787-makes-emergency-landing-amid-battery-indicator.html

Further reinforcing the perception lithium ion batteries are dangerous. But this is interesting:

In a worst-case scenario in which the batteries do burn, they are designed to do so in a way that doesn’t threaten the aircraft, Sinnett said. If the jet is airborne, smoke is supposed to be vented out of the compartment so that it doesn’t reach the cabin, he said, and all of the battery cells can ignite without harming the plane’s ability to stay aloft.

What is interesting to me is there is no fire suppression equipment mentioned, just containment and fume evacuation devices. I know it is said that thermal runaway lithium batteries cannot be extinguished; but, is this really true? Are there no chemicals that will suppress this reaction? What happens when the battery in a cell phone or laptop runs away? All these events have gotta be frightening, especially in flight.

I know from Chem classes Li is stored under dry mineral oil. Any ideas?

 

[dgpcolorado]

...You do realize that most modern cars are fly by wire in that they don't have a direct mechanical link to the throttle or steering?

Isn't the Leaf fly by wire?

I know my Prius is.

As others have mentioned, cars still have mechanical steering and braking. But, even if that were not so, there is a big difference between a ground based car that loses steering control and an airplane that loses three axis controls.

It is similar to the old question: which would you rather be in, a car that has the engine die or an airplane that has the engine(s) die? With the former you pull over and stop. With the latter you look for an open area that you can glide to for a crash landing, assuming a runway isn't convenient. Statistically speaking flying is safer than driving, fewer drunken or texting pilots I suppose, but in the case of catastrophic systems failure I'd rather be on the ground.

Unfortunately there aren't any ejection seats on the 787 for when that battery catches fire...

I've often wondered what happens to airplanes when the EMP hits from a nuclear blast. Do they all fall out of the sky as all the electrical systems are fried?

 

[Ingineer]

I've often wondered what happens to airplanes when the EMP hits from a nuclear blast. Do they all fall out of the sky as all the electrical systems are fried?

If there is nuclear blast, I think airplanes are the least of your worries! :shock:

Although, it's quite possible an airplane, at least one made of aluminum, could survive a milder EMP. It really depends on the strength. I know the military has spent billions on hardening their electronics.

Your basic Cessna 172 with magnetos and a carburetor will probably stay running.

-Phil

 

[Ingineer]

Also, the Lithium battery in the 787 is for cold-starting the APU when there isn't ground power available. Once it's running, the battery is not needed. In fact, it seems like if I were Boeing, I'd temporarily remove the batteries for airlines that are always going to start with ground power. There are many planes that need a power cart to start anyway.

Though it's probably impossible to do because of FAA regs with out some major re-certification.

Tony?

-Phil

 

[ebill3]

Might not the battery also be used as a final redundancy in some systems? Perhaps such as wheel brakes, as I understand they are electrically actuated, not hydraulic.

 

[Ingineer]

The battery is 65lbs, and it's 28v using Yuasa cells. (capacity about 2.2kWh)

Here's the battery that failed casatrophically:

Here's what they look like new:

Here's the other one that failed (though not catastrophically):

-Phil

 

[TonyWilliams]

Also, the Lithium battery in the 787 is for cold-starting the APU when there isn't ground power available. Once it's running, the battery is not needed. In fact, it seems like if I were Boeing, I'd temporarily remove the batteries for airlines that are always going to start with ground power. There are many planes that need a power cart to start anyway.

Though it's probably impossible to do because of FAA regs with out some major re-certification.

Tony?

-Phil

Nothing will happen to fix this without an Airworthiness Directive (AD) issued by the FAA. That will required all the usual testing protocols. Recertification of a plane is EXTREMELY rare, but it has happened. I absolutely do not expect that in this case.

I do not know the systems of the B787, but they don't need these batteries to start an APU. Just a regular old lead/acid or NiCad has been doing the job for many, many decades.

The concept of introducing lithium was for a backup to the electric control systems; in other words, it is only needed when the **** really hits the fan. I believe the B787 also has a RAT/ADG (air powered generator), but again, I'm neither qualified, nor have I studied the B787 systems.

Edit: every transport category aircraft will have an emergency 28 volt DC buss, and this battery is likely part of that. It is required to provide 30 minutes of power to critical instruments while getting the plane on the ground. Of course, the electric powered brakes and control surfaces of a B787 have additional emergency electrical requirements.