Extreme heat can lead to battery corrosion that shortens the average car battery life. Chemical reactions are driven by voltage or temperature, so the hotter the battery is, the faster the chemical reaction will occur.

Can hot batteries cause a fire?

Even batteries with a small voltage like commonly used AA and AAA alkaline batteries can start a fire under the right conditions. If the negative and positive posts of the batteries come in contact with something metal, the heat begins to build.

What causes a hot battery?

If your battery gets very hot, though, it may indicate that your charging system has some problems. On a weak battery the alternator may be working harder than normal to keep it charged. This constant charging will cause the battery to heat up. A faulty alternator can also cause the battery to heat up as well.