UPDATED 14/11/2013 I did a small test to see how a cheap cashbox would hold up to a burning lipo. This was done with a fully charged 3S 2100 MAH lipo battery and the results gave me confidence to use this method for charging and storing my batteries....
A few people have asked how many batteries can be stored together in this cashbox, I cannot answer this question and am hesitant to voice my opinion as this is the internet after all. All I can say is that I own three batteries with similar capacities to the one in the video and I am happy to store them together but always charge them separately.