Elon Musk: Boeing 787 battery fundamentally unsafe
A point to be made about Evolution and Biology, because we know this:
Large animals dissipate heat slower than small animals. Heat generation in animals (and batteries) is proportional to their volume (and in batteries to the square of the peak current), heat dissipation proportional to surface area.
The Ratio of Volume to surface area is roughly the radius of an equivalent sphere, radius r. Heat increases proportionally to r cubed, dissipation to r squared. The bigger the animal (and battery) the more possibility it can overheat. The bigger the battery the higher the peak current, and consequently inherent heating properties.
Which is why elephants have large ears, and wet themselves down, and hippos live in water.
Here’s the point from Musk’s email:
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,” says Musk.
Here’s Mike Sinnett, Boeing’s 787 chief project engineer’s quote:
“I design a cell to not fail and then assume it will and the ask the next ‘what-if’ questions,” Sinnett said. “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.”
Mike did not consult battery experts in the automotive field, where there is the most expertise in hybrid technology, (or he would have stated that he did).
Mike appears as an arrogant asshole from the tone of his quote. Use of the word “I” is the clue — taking credit for others’ work, resulting in enemies (lots of them) inside Boeing.
Boeing executives know of Musk’s comments, and there is too much at risk for Boeing not to pay attention to an expert in the field.
If Boeing is smart (and they’d better be), they will have a plane full of Boeing Engineers going to see Musk right now, by Monday Mike Sinnett will be unemployed, and Musk will have a (large) consulting contract.