LI -x batteries do NOT need Oxygen to continue to flame- the chemistry is such they generate thier OWN oxygen.
ELT batteries are NOT chargeable
ELT is not normally connected to Aircraft electrical system- note I said NORMALLY - but ' sneak" circuits due to poor grounding, flaky connections, crossed wires, etc ** could ** possibly exist. Battery protection diodes can fail for example internally, etc. LI-x fires can be like a cutting torch.
Model airplane LI-x batteries can and do catch fire if abused/shorted/etc but they ARE rechargeable.
DWS and Ancient Mariner, after reading your posts and looking at the picture of the burned battery, It seems like I have a lot to learn about Lithium batteries. Some of them are really scary. Maybe, like the battery in the closet, the one in the ELT caught fire for no apparent reason without even needing "crushed wires". That is extra scary. In a hermetically sealed box, it might be more like a bomb! I'm making the lithium battery too analogous to more common batteries I'm accustomed to. I may not always be right, but I'm clever enough to know, when I need further study. As much as I know, I learn a lot from our brainstorming, and appreciate everyone's patience with one another.