Most acid electrolyte batteries "Fume" just an imperceptable bit, and
the result is an almost undetectable coating of electrolyte on the case,
providing a direct circuit to "Ground", in this case, the concrete
floor. Result - dead battery. The wood acts as an insulator.

John Rodgers
88 Gl driver

Michael Townsend wrote:
>  I thought that "never store a battery on a concrete floor" thing was an
>  urban legend that everyone followed just "in case!"  What is the science
>  behind it, and why does Optima claim their spiral cells are immune from it?
>
>  Michael
>
>
>>3) Gell-cells are the greatest invention since sliced bread.  They don't
>
>  spill, out-gas (noticeably) or rot your floor.  They are prone to plate
>  dammage like a wet-cell though, so never store them on a cement floor.
>