They don't "explode" per se. It's called thermal runaway. Essentially, it's what happens if the two opposite charged elements come into contact with one another. There's MASSIVE potential energy crammed into those packs. Obviously, they're moving a bus and passengers. When thermal runaway is initiated, there's no stopping it. It has to burn out. Absent a lab environment, there isn't much known about how to contain the "fire", "explosion", etc. Thermal runaway. It's a concept I think any potential EV owners should be well aware of, and take into consideration. I've resolved to myself to not be burned to death in my mode of transport. The Batt packs need to be fore or aft of the cockpit. Spring loaded to "jettison" the batts if they start a "thermal runaway". I'd feel a lot better about electric single mode transport if I'd seen an advertisement like that. It's all irrelevant though really. The energy density of electrons as compared to hydrocarbons is negligible.