You raise a really good point about the reasons for Musk's collaboration, Nadine. Obviously, no one but Musk knows the full reason, but I imagine there is an element of self-preservation in this. Lithium-ion batteries are getting a going-over in the popular press right now, and some news stories have wondered aloud if lithium-ion is appropriate for electric vehicles. Whether those questions are fair or not, I would imagine that Musk wants people to know that Tesla's battery configuration works safely because the design allegedly makes better allowances for heat dissipation. It's hard to blame him for that.
Regarding the issue of whether a battery management IC, by itself, was sufficient protection for the Boeing batteries: We asked Donald Sadoway of MIT that question by e-mail, and his response came in after the story deadline. So here's his response, which arrived late yesterday: "We have evidence that whatever the electrical demands are in the 787, the IC alone doesn't prevent fire. So perhaps the IC isn't right, perhaps the IC is right but the execution is flawed, or perhaps there is some other factor like decompression/compression, which is the result of ascent and descent."
As an alternative to overcharging and heat dissipation how about over discharging? Over discharge damage is the reason many RC enthuiasists charge their lithium ion batteries outside.
Boeing has recieved 100 batteries back from the airlines as defective. It appears the majority have been inadvertently discharged until the battery low voltage cutoff tripped, disabling the battery. In ANA's case 5 of 10 returns were disabled by the low voltage cutoff. Once a lithuim ion battery has gone below the low voltage limit it is very hazardous to charge. It seems risky procedure for the user to bang up against only battery safety stop during routine ground maintenance. Maybe some batteries have very nearly tripped but were unknowingly flown.
Anticipating the question of why don't the battery electronics cut off discharge at a higher voltage, I don't know. It might have something to do with the fact the batteries are also a last ditch power source to keep flying. I can imagine a situation where you would want every joule you could get out of the battery and willingly scrap it later.
I would discount poor high altitude cooling. The batteries are in the pressurized part of the plane, an equivalent to an altitude of 6000 feet so you still have good heat transfer.
Great that you're keeping on top of this story, Charles. I guess now what we're waiting for is Boeing to admit what it has done wrong and then come up with a plan to fix the problem. I was sort of defending them at first but it actually seems like a fairly major oversight to not proivide a proper cooling system...but maybe they thought they did and it was just an honest mistake. I will continue reading your coverage to see how this unfolds! Let's hope it's a good ending for everyone and Boeing sorts this out.
Wow. Thanks for this, Chuck. Definitely a developing story. I'm delighted to hear that there is collaboration (or at least a coalition) of lithium-ion battery users that are willing to swap experience with these systems. I'm sure this type of information sharing between CEOs has happened since the dawn of time, but I'm encouraged that it can be facilitated by social networking such as twitter and not left to chance meetings on the putting green at the club. I'm sure networking at the Engineer level is still best found at the Dearborn Heights Applebee's, but online story swapping is another emerging development that helps to accelerate the exponential technology development curve...
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