As generally known lithium polymer batteries (lipos) may catch fire, for example as consequence of deep discharge, overcharge, (internal) short circuit etc.
As a hobby rc car driver, I am thinking about the dangers of a possible lipo fire. To prevent the fire one could use a lipo box like batsafe. However this doesn't filter toxic fumes.
Now there are different opinions found on the net about those fumes, one (as in the faq of bat-safe) says that the fumes dissipate over time. So to say, after a possible fire inside of the box, you just have to open your windows for a few hours or days and everything is gone.
Other people say that parts of this toxic mixture could make a complete house uninhabitable, because material will distribute all over your house and emit toxic fumes, which will make you ill over time (see here)
But what really causes damage is the extreme smoke development. Besides highly toxic and corrodes your lungs with every breath irreversible.
No use for a batsave or ammunition box, the smoke will find its way, these things are only good to seal off fire from the rest of the apartment. The only exception would be a connection to the outside.
This extremely dense smoke will push you through all the cracks,through all the boxes, through all doors (even closed) in the house......
.....The result is an uninhabitable apartment that must be completely gutted.
At least that was always, without exception, the statement of the damaged ones as the forums were still full of reports about lipo fires.
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However I don't see how to estimate which opinion is true. So I try to post this as a kind of fermi question to chemistry stackexchange and hope for some insights.
You may assume that four 3s lipos like this burn inside of a lipo box (which prevents the fire) in a basement of a house in a room with 100 m^3 air and the possibility to open larger windows or a door, if needed after the accident.