Lithium Battery Fires - Caused By Air Pressure Changes

Low pressure is part of the standard testing procedure of lithium batteries...

http://www.ul.com/global/documents/newscience/whitepapers/firesafety/FS_Safety%20Issues%20for%20Lithium-Ion%20Batteries_10-12.pdf

How many pressure cycles are performed? This report does not indicate anything more then one. My experience from avionics test is only one decompression test application is required for a top level assembly (per RTCA DO-160 environmental test standard). Airframe vendors may have a separate qualification requirement at the component level of test.

For electronic component level tests, only thermal cycles and vibration is performed per airframe manufacture (e.g. Boeing) requirements. Avionic components are typically 'hermetically sealed', so extensive pressure testing is considered moot. It would be interesting to see what the 787 test requirements were for their battery qualification. But I think they buried this with a QC manufacture problem of the cells.

I see no evidence to suggest that lithium batteries are required to be hermetically sealed. It's no doubt a good idea, but I see no specifications or test requirements.

Since lithium burns in the presence of oxygen, or air, lithium batteries need to be hermetically sealed. In that case, who cares what happens to ambient air pressure.

Given that lithium batteries are hermetically sealed, has there been testing involving many repeated cycles of ambient air pressure changes, to see if that might rupture the seal?

As the air pressure tends towards zero, no fire is possible.

It just struck me, why would air pressure changes outside of a lithium battery affect the inside as in a properly working cell, there is no gas inside, just solids and liquids......expansion close to zero with external pressure changes...

Even if there is a small amount of gas of some sort, its very easy to have a sealed, but flexible area to allow such pressure changes to take place.....

I looked around on the web and could not find a mention of gas inside a normal working cell, except when a cell was damaged and overheating.....then gas is developed.....

I would expect that batteries for aircraft, they are fully tested for pressure changes.....