What happens when you burn a battery?

well this all deoends on the type of batter if its a battery with a metal jacket then the preassue will increase as the acid inside starts to boil and it could explode sendin the acid with is costic and very hot at this time throughout the air so not recommended lol

as for a car batter or one cased in plastic it culd rupture and the acid may also cause the housing to fail and bust to