Just to digress but still batteries, but Nicads, back in the seventies I was using ultrasound equipment that used rechargeable Nicad battery packs. When we returned from an inspection we would remove the metal clad Nicad pack and place it onto a bench equipped with chargers, one day returned and placed the used battery on charge as usual and left the workshop in search of a very welcome cup of coffee. Quite soon became aware of a crackling sound accompanied by acrid, probably highly toxic, smoke emanating from the equipment room, inside the battery that had just been put on charge was spitting flames and smoking furiously. Power was disconnected and said battery unceremoniously dumped outside, once it had cooled it was retrieved and a post-mortem carried out. The metal case was opened and the cause of the fire was a short circuit with one of the connecting links of the Nicaad cells that had chafed and the insulation failed and the connecting link core made contact with the metal casing of the battery pack, giving an instant fire. I was quite disturbed by this incident because we regularly carried our test equipment with us on aircraft flights, the thought of such a re-occurrence whilst airborne with the equipment stowed in the freight hold didn’t bear thinking about. I am glad that airlines today have at last realised the possible problems of batteries, nicad or li-ion, if carried in aircraft.
Dave W