my car has been stood for a while and i have to jump it off everytime i work on it, yesterday i jumped car off with mains powered jumppack and i took a wile tostart usually fires up first time, i move car and replaced a door, then i went to move my car back, i connected the jumppack and went to start the car and smoke was filling the drivers side of the car looked like it was coming from the footwell, i immediatley disconeted the jump pack and pondered for a while then gave it another go, upon connecting again the crocadile clips felt like they were sticking to the battery, then BOOM the battery exploded any ideas please