Why did my batteries overheat?
My television remote control stopped working, so I replaced the batteries. The new batteries got really hot - too hot to touch. What causes this to happen?
Batteries can heat up if you have a short circuit. Instead of the electricity going through a circuit where it is used up in various ways or resisted, it just goes straight through the battery, and is then conducted back around into the battery again. All of the energy from the battery is released as heat in the battery, and it can get dangerously hot.