Battery vs. the floor

[snopes]

I had a car battery charged the other day and it was sitting on the sidewalk and a neighbor told me the sidewalk would drain the battery. He said somebody once explained this to him, and that it was no joke. Is he having me on?

http://www.mailtribune.com/apps/pbcs...NEWS/706130322

The version I always heard was quite vague: setting the battery on the ground (be it concrete, grass, dirt, whatever...) caused it to lose it's charge. Nobody could ever explain why it happened, but they all swore it happened to them once.

[Eddylizard]

I'm sure we've discussed this before somewhere, perhaps on the old board.

I can't reallly see hoe this could happen, The casing of the battery is a good dielectric, otherwise you'd get zapped when you touched it. Concrete is a fairly good dielectric, except perhaps for green concrete. So how could electrons leak from the battery to earth?

The only thing I can think of is that batteries are not particularly fond of being cold. Car batteries also degrade if you do not run the engine to charge them at least every two weeks or so (I do not fully understand the process) as stated in the article. It's reasonable to assume that anyone who takes a battery out of a vehicle intends to store the battery for some time.

So maybe it's not putting them on concrete, but not charging them on a regular basis that causes the problem. So it wouldn't matter if they were stored on wood, grass, steel, dirt or in the engine compartment of an unused vehicle, the problem would still occur.

I also once had a tour of the now defunct data services division of Mobil in Maidstone, which was avery impressive setup. The had about 2,000 lead-acid batteries in their UPS room, a quarter of which were sitting on the concrete floor. They did not seem to think it was a problem.

[Em]

Originally Posted by Eddylizard

I'm sure we've discussed this before somewhere, perhaps on the old board.

You're right: Chow and chow.

[RichardM]

Actually concrete is a fairly good conductor. Google "Ufer ground" for more info on that. And battery casings used to be sort of conductive.

From my understanding of this myth, as told me by a number of auto mechenics and auto shop teachers, the myth started when back yard mechenics noticed that when they took a battary out of a car and set it down on the cement floor while working on or replacing engines after they replaced the battary back into the car it was dead.

What most of these people forgot was the amount of time that the battary was sitting, most auto shops will put battaries on a trickle charger to keep the charge up in the battary, or the battary was in pretty bad condition when they took it out of the car, How many people check their battaries before the battary starts giving them problems?

Hence the myth was born, put a car battary on cement andd it will go dead because the cement drains the battary, even if you put a block of wood between the battary and cement.