"Every liquid does evaporate, including any acids (not to mention that molten metals such as extremely hot iron in liquid form would also evaporate if you keep subjecting it to higher temperature).
"

Dear Eric,

of course anything can evaporate. I was rather referring to 'normal use' temperatures, where, in a battery (accumulator) you only lose water and don't have to refill acid because acid, under normal use, does not evaporate. My advice to a question thus was to refill distilled water only and no acid.

On the other hand, should it be a custom made vehicle used in exploration of active volcanoes, or simply a vehicle that happened to fall in to an active volcano, you would be correct and everything would melt, including a battery. And driver.

Also, according to quantum theory, it is no use to have a battery in car anyway as the atoms of the battery will travel through the atoms of the car so in the end you'll end up having the battery on the ground of your garage. And your car will travel thru the garage's walls. Only if you give it time.