rottenray:
We're getting closer to the reason for at least one of the failures.
Flightglobal writes that a short was found in cell # 5 of the JAL battery.
If a cell grossly overheated, it wouldn't be surprising to find that the
separator material broke down eventually, whatever it's made of.
What they are also saying is that they are not sure if an overcharge
condition occured in a single cell, which would have caused thermal
runaway affecting the rest of the battery.
Still early days, but my money is still on the charger or temperature
sensing within the battery. Yuasa have been shipping these cells for
years and they are even used for space applications, so find it difficult
to believe there's a fundamental design fault in that area...
Regards,
Chris