I think these were nickel hydride batteries. ..Think they can be dangerous...Lithium Hydride batteries are a lot more dangerous. A UPS cargo plane was downed because of a Lithium hydride battery on fire in the cargo hold..all died. The Boeing Dreamliner fleet was downed for about 6 months because of lithium hydride fires in the Dreamliner. Lithium makes a very energetic battery...one reason it's so energetic..is because it's energetic...Lithium will burn in air, and it will burn in water. The oxygen in water, will fuel a lithium fire...that's energetic!!!! Bizarrely enough, chunks of pure lithium are stored in oil..kerosene, mineral oil, etc. The oil keeps the oxygen away from them ...they won't burn!!!.