The battery cells are individually wrapped in aluminum type foil. Each cell is 3.7 volts. It will tear about as easily as a capri sun fruit drink container. If you tear the foil the battery must immediately be destroyed per the directions if it doesnt ignite. I think you soak it in salt water to "kill" the battery and stop any threat of a chemical reaction. I have dropped mine on the concrete accidentally and they were ok but it didnt land on a corner and dent any part of the calls. I wouldnt use it if you altered the shape of the cell from an impact. Also you can check the battery to see if it is getting hot during charge and use. Mine are always slightly warm but not even close to hot at the end of a flight. When charging they are completely cool to very very slightly warm using a 1 amp charge rate. I have seen one very slightly torn in a crash and it smouldered a little from the tear. Once they ignite they burn fast at about 2000 degrees from what I understand. They will burn through the bed of your truck, its an extremely hot fire. SOme of the thunder power packs can discharge at about 13 amps with a burst of up to 18 amps momentary discharge.