mathewsjl...
This from Machinbird...
"As a betting man, I'll bet that the issue with the battery is actually with the charging system and insufficient feedback from the battery to the charging system regarding cell temperature. The charging system should not continue to charge a battery that is moving in the direction of thermal runaway."
I have read the special consideration re: LithIon issued to the 787 program by FAA. Other than failing almost all of them, utterly, in the emergencies, I did not notice a restriction in re: charging of a discharged system, LiIon.
This would be the salient issue, no?
The 787 is a very fresh and different approach to power/energy systems in commercial widebody. It is truly an electric jet.
More than ten years ago, I was involved in fireproofing a security system. The solution was weighty, but performed to spec. Lightweight ceramic and even lightweight concrete (sic) have been available for decades. The photo of the burnt and uncontained contents of the APU battery show a unit that has performed well, except at the top. It is difficult to imagine that a solution for the safe retention of the utility of such a high performing system cannot be supplied.
What is disconcerting is the thin limits that are exposed relative to weight saving in the E/E Bay. The a/c itself is amazing in its approach to efficiencies. A little cautious application of insulation and monitoring might (might) have saved the issue from reaching the state it did....
The electrical system itself cannot be re-engineered, without different engines and miles of 'plumbing'....