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Re: Dead Batteries and Electron Flow

To: Dean Craig <dcraig@u2systems.com>
Subject: Re: Dead Batteries and Electron Flow
From: "W. R. Gibbons" <gibbons@northpole.med.uvm.edu>
Date: Thu, 2 Nov 1995 00:30:51 -0500 (EST)
On Wed, 1 Nov 1995, Dean Craig wrote:

> 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

I think this is a great idea.  Except, the only current flow that can
discharge the battery is the current flow between the terminals.  Positive
charge can't leak off to ground all by itself.  Law of electroneutrality 
(passed by congress in 1892) says it can't happen.  

Still, if you consider that the battery generally is covered with crud, 
some of which is salts, and water condenses on the cold case, and the 
salts dissolve to make a conducting solution, and there is a trickle of 
current between the posts--it makes sense to me.

> 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.

Don't agree about these three lines, because I think the flow between the 
terminals is the only flow that matters, but the general idea sounds good.  
Last year, my garage floor was covered with a film of condensation for a 
couple of days during a sudden warm spell.  I think I will keep my 
battery in the car where Healey meant it to be.

   Ray Gibbons  Dept. of Molecular Physiology & Biophysics
                Univ. of Vermont College of Medicine, Burlington, VT
                gibbons@northpole.med.uvm.edu  (802) 656-8910


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