Re: NVG BATTERIES - ever had a problem?
The MoD commisioned both QinetiQ (when they were DRA) and Marconi to carry out ballistic strike tests on Lithium Ion batteries when they were brought into service to supplement Clansman, BOWMAN and BMN replacement. The results were indeed alarming, especially the QQ tests, in which the explosion destroyed the rig holding the battery. Both are available within MoD on video. The effect is not immediate (at least from these tests) so the bearer has the opportunity to offload the radio.
There is a snippet of such an event in the film Black Hawk Down.