[QUOTE=Phil from Maine]
That is what I have always done with my motorcycle and boat batteries and I believe that that procedure is the industry recommended procedure. I do however monitor the batteries as the Winter progresses and have been taught by others never to leave batteries on unheated concrete.
EDIT: on ground slabs whether heated or not.
There was a time when battery cases were made out of a special wood however with the advent of plastic battery case construction drastically changed sometime in the 1940's I believe. With wood cases, yes, you would not want to place on a concrete surface as it would discharge the battery. However with plastic that is no longer the case - pardon the play on words here. If it were a problem, my 9+ year old batteries would no longer be useful or work as well as they do.