26 Jan 2016 22:01
Yesterday my DEKK branded aftermarket NP-FW50 battery for Sony cameras exploded in its similarly inexpensive swappable-plate wall charger without warning after charging from dead for a few hours. There was a moderate "pop" like something falling off a shelf and a moderate "electrical" smell; no power flickering. Eventually I discovered the source. The battery had ejected itself from the apparently undamaged charger and fallen to the floor about a foot away. Its plastic shell had broken pretty much along its seam. One of the two prismatic metal cells remained against its side; the other had bulged, blown open at one end, separated from the pack and its plastic cover, and blown its contents a few feet across the carpet. The remains of the contents consisted of coppery foil, black dust, and fine tissue-paper-like material. The foil melted itself a few millimeters into the plasticky carpet fiber like cigarette burns, binding in some of the black dust.
The mess was not particularly noxious to clean up but the carpet will need to be patched. Expensive brand-name batteries reportedly explode too. The incident does show the importance of transporting lithium-ion batteries exactly as airlines and shippers request so that any fire they may start can be safely extinguished.