BATTERIES SHOULD NEVER BECOME WARM OR HOT IN THESE LESSONS
SITUATION: Battery gets warm or hot to the touch. Sometimes a battery that is getting warm will make popping sounds as the internal fluid starts to boil or gas is produced.
CORRECTION: Disconnect from circuit immediately. A heating battery can be dangerous! Wear safety goggles.
This is almost always caused by electrically connecting the positive output of the battery to its negative. This is a short circuit causing the batteries internal chemical reactions to run at the fastest possible speed. This reaction generates heat.
Find and remove this connection. Do not try reconnecting the battery until you are certain the problem has been corrected.