> The batteries used in the 787 are highly unstable (lithium-cobalt) > compared to LiFePO4... You would think that after Sony had problems > with LiCo batteries in laptops a few years ago, Boeing would be > more careful...
Whenever someone uses a new technology, there is a tendency to pretend it is just like the old one, only better. The people selling it will encourage this view.
So, the engineers will plan for the failure modes they KNOW about, based on what the PREVIOUS generation of battery did. But they can't plan for failure modes that they DON'T know about.
Sony got "burned" by the LiCo batteries because they didn't know they could burn so dramatically. After all, no previous battery technology (lead-acid, nicad, nimh) could burn like that. As I recall, there were quality control problems in the cells that could cause internal shorts, which started the fires.
Presumably, Boeing knew about this. So, they probably set up quality controls to prevent that type of failure from happening again. But, there were obviously OTHER failure modes that they DID NOT know about.
All types of lithium batteries burn. The LiCo cells, because of their higher voltage and higher stored energy, burn worse than LiFe cells. But it's like comparing a box of matches to a box of kindling. Once lit, they both burn dramatically.
And, any type of battery can provide a source of ignition. It can supply enough voltage and current to heat something red-hot, which can start a fire in surrounding materials, even if the battery itself won't burn.
It will be interesting to find out what actually caused the fires. That will be the only way subsequent designers can learn from it, and avoid making the same mistake again!
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