I have never heard the sound come from an engine compartment as a battery exploding when I turned the ignition. The vehicle never turned over... BOOM! There was battery acid all over the engine compartment. The battery case was split along the side adjacent to the motor and the top had lifted up along 3 sides. We have no idea what caused this to happen. Our mechanic brought a new battery to where we were located and replaced it for us. The vehicle started once the new battery was installed. We are trading it in as soon as we find the right vehicle for us. This was the original Mo-Par battery.