For what Phaximus said about the bags
http://www.youtube.com/watch?v=ZEkewCjiDs0 Was gonna post a vid, but got distracted, and closed it

Personally I say get a ammo can
Here is a test of an ammo can with a few lipos in it
http://www.youtube.com/watch?v=1jwS2puM800 Notice the cell was snuffed out almost immediately as the guy said the paper he put by the lipo wasn't even burnt