1. Urban myth

2. Alkaline cement/battery acid

3. Dust dirt and moisture

4. Basement floor

CJT said he never had a problem, but didn't mention anything about
time. How long ? Nobody ever said it was dead in minutes, or even
hours.

A buddy and I have been discussing this, after reading the responses
and I can no longer summarily dismiss the effect, if the "urban legend"
is indeed true. At this stage I must admit that there is a possibility.

2. A reaction between whatever solubles are in or on the cement, along
with the highly acidic content of the battery housing, which has some
porosity, is an interesting possibility.

All of this might be enhanced in more humid climates. Even on cement,
even if it doesn't rain, if left long enough metals will corrode or
rust on the bottom.

3.Basement floor : While copper is an excellent conductor, cement is
not. That is not to say it is a good insulator. Your legs act as wires,
not very good wires, but functional enough to kill. If you are barefoot
on cement, it's not making all that good of a wire either, but look at
your footprint and you see the cross-sectional of this wire. A bit
bigger than the wires in your basic 12-2 Romex you think ? A copper
conductor of that size could carry thousands of amps. It needs alot
less to burn you, or to discharge your puny battery over time.The
linear resistance of a piece of wire is inversely proportional to it's
cross sectional area. So what do we have here, how many ohms ?

Actually I would be at a disadvantage here with my 13 wide sized feet.

When I want to know if something is true I need to prove it to myself.
Thanks all so far. I play Devil's advocate against my own initial point
of view for that reason. All these factors are evidence that this myth
might be true, but initially came from personal obsevations. Cause was
attributed to effect, but the matter was not looked into further.

JURB