People keep asking about setting a car battery on a concrete floor somehow ruining the battery. Here is the final answer on the subject. I have the 1930s Popular Science with the original tip in it (but don't ask me which issue). The auto tip was: "Leaving a car battery on a concrete floor will ruin it." I have seen three concrete floors ruined by leaving car batteries on them. Acid vapors ate away at the concrete. That "it" in the auto tip has too many antecedents.