Elon Musk: Boeing 787 battery fundamentally unsafe

Not exactly. The larger battery is because the APU is larger. The engines are started on APU power, not directly from battery power. You are correct that Lithium Ion batteries are significantly lighter than older NiCad batteries.

I found a Boeing technical publication that discusses the power architecture of the 787 and how the battery comes into play. Kind of interesting:

http://www.boeing.com/commercial/aeromagazine/articles/qtr_4...

Page 4 says this:

"The power source for APU starting may be the airplane battery, a ground power source, or an engine-driven generator. The power source for engine starting may be the APU generators, engine-driven generators on the opposite side engine, or two forward 115 VAC ground power sources. The aft external power receptacles may be used for a faster start, if desired."

So the battery seems to be very important when you're somewhere with no ground generator. The battery starts the APU, then the power from the APU starts the engines.

On a large jet airliner, the engines are not started by battery power; they're started by the APU, which is basically a much smaller engine (if you look at videos of airliners, you can see it venting out the tip of the tail). The APU also provides emergency backup power and cabin pressurization in-flight if the engines fail.

The 787 is unusual in that it's a "bleedless" aircraft; it uses other systems -- some of them electrically-powered -- to supply compressed air for various purposes, rather than "bleeding" compressed air from the engines. The batteries are part of that, and have to be onboard because the plane needs compressed air while in flight.

While I can't dispute anything that is being said I think it is unfortunate that this is playing out the way it is.

I can't dispute it because there's virtually no reliable publicly-available information on the design of this battery pack. I think it is unbecoming of an engineer or scientist, particularly of prominence, to voice such opinions without access to design data from the source.

Before I could even begin to dare to voice opinion I would need to study CAD models, electrical and electronic diagrams and test data. I would also want to have access to representative samples of the packs for inspection. Even then, unless there was something so obviously wrong with the design that a conclusion was inescapable I'd refrain from rash public comments and redouble evaluation efforts to make sure every angle was evaluated exhaustively.

Having designed high-performance, high-current chargers in the past I know a thing or two about battery technology, particularly when it comes to failure modes. When you are doing that kind of work you purposely test designs to induce and document failures and design around them when possible. Yes, I have blown-up lots of batteries and chargers. And, yes, this means that if you've worked with high-energy battery technologies (and electronics in general) you get a good general sense of the good, the bad and the ugly. I get it. And I would still want design and test data from the horses-mouth before uttering a word.

The problem here is that the engineers at Boeing are not clowns. Unless you consider people with advanced degrees from the top engineering schools in the world to be clowns. This is an industry that takes what they do very, very seriously. A lot of work, simulation and testing goes into all of their projects. I could not imagine the engineers at Boeing slapping together a battery pack for something like the 787 project without years of work and testing. I just can't see it. Yet, they are human beings which means that mistakes and miscalculations do happen. That's true of any human endeavor.

And so, making such comments is also disrespectful. I understand competitive forces very well. But there's a time and a place for that.

If he is wrong he'll have a lot of explaining to do. If that is the case I hope he'll devote just as much energy to issuing the necessary apologies and clarifications as he does being critical.

EDIT:

If you ever get a chance to visit the Boeing factory in Seattle it is a must. I did many years ago. As an engineer it was fascinating. I remember one test they showed us where they clamped down (I think) a 747 wing in this huge structure and used incredibly large hydraulic jacks to bend the wing up and down repeatedly for failure-mode testing. I could be wrong, but I think I remember the peak to peak bending at the wing-tip was in the order of ten stories. I could not imagine designing and building an electro-mechanical structure that could do that and survive with enough functionality to get people safely back to ground level.

I think this might be it: http://www.youtube.com/watch?v=WRf395ioJRY

Here's video on the 787 wing: http://www.youtube.com/watch?v=sA9Kato1CxA

Also: http://www.wired.com/autopia/2010/03/boeing-787-passes-incre...

So, yes, please, I think it might be wise to remain quiet and let those who actually have real data go through a proper investigative process and get us real answers. If anything out of respect for the work, talent and dedication that goes into designing and building such amazing products.

I don't know. I could see it getting to a less tech savvy media outlet and become Founder of Tesla openly admits batteries in their cars are fundamentally unsafe.