OK, I'll throw my hat into the ring on this one... The _real_ reason why you
should store your batteries on wood or some other insulating material and
not directly on a concrete floor is to insulate your battery both
electrically and thermally from the cold, damp concrete.
Visualize the following scenario:
A long period of cold weather causes the concrete floor and the battery in
direct contact with it to cool. When the weather warms up the cold concrete
and battery are consideraby colder than the surrounding air and will stay
that way for quite some time. This causes condensation to form on the
exterior of the battery. The condensation creates a current path from the
positive terminal of the battery to ground (the damp concrete) and the
stored charge in the battery is slowly drained away. Condensation will also
cause a slight current flow between the terminals of the battery, but the
negative post has a much smaller surface area than the contact patch between
the bottom of the battery and the concrete so this has a lesser effect.
Condensation will still form on the battery if it is on wood but the battery
will warm much more quickly to the surrounding air temperature, allowing the
moisture to evaporate and remove the current path between the posts.
Dean "Damn I'm smart!" Craig
'64 B
>Will writes:
>
>----begin major surgery----
>
>>>>Electicity conducts into the humid atmosphere,
>>>>bouncing from water droplet to water droplet, and then falling to the
>>>>concrete floor and finally to "earth," negative or otherwise. Out of the
>>>>battery that is, forever.
>
>---end major surgery----
>
>I don't think that's quite right. Kirchoff's current law states the sum of the
>currents exiting a node equal those entering it. Or more precisely, how does
>the current enter the other terminal of the battery? If you assume the
>conductive atmosphere theory, the current flow (and the subsequent dissipation
>of energy as heat) would be, I think, between the battery posts. Therefore, it
>shouldn't make any difference whether the battery was on a concrete floor or
>not. It just may be that the humidity is greater near a concrete floor. An
>interesting experiment would be to place the battery in a pan with a small
>amount of water and compare.
>
>I don't know about you but I'm going out right now and see if I can get a
>government contract to investigate this!
>
>
>David Macedonia
>(an electrical engineer with way to much time on his hands)
>macedonia-statc@kaman.com
>
>1966 MGB
>
>
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