Lyman:
With a "vented" enclosure at 41000 feet and 6000 pressure altitude inside, is there a problem? Wouldn't the drop in pressure in the box eject all the contents of the battery enclosure instantly? Explosive decompression?
I would expect the venting system would be designed for a more controlled release.
The combusted products, exiting the "vent" pipe, will not ignite the Hull?
God borbid the enclosure leaks burning electrolyte on to the fuselage structure, (epoxy resin), how is that potential "mitigated"?
In the case of JA804A (NH), electrolyte that reached the bottom of the EE bay was vented out of the plane (via either the outflow valve or a drain valve - I am not sure which). This is the brown streak visible on the underside of the fuselage.
The airflow cooled the material before it could do any real damage to the CFRP of the fuselage. This would also be the case with a controlled vent directly from the battery container.