Li Batteries & Vibration
The Yuasa battery being used in the 787 and what appears to be its prismatic cells are unfamiliar to me but our experience with all Li batteries is that there is a threshold vibration level that will cause rapid cell damage and lead to shorting behavior. In our aerospace application we've tested pretty much every cell type and none of them are particularly tough. Our application has a considerably higher vibration level than most transport aircraft however. I am sure that the battery in question was qualification vibration tested before it ever flew but I wonder if the actual in-service vibration level of that battery installation is what was expected. Our experience is that if the vibration threshold is exceeded the failure is prompt. The operating temperature of these cells is a issue as well. Just how hot does that compartment get when the aircraft is on the ground?