Re: Lead-Acid batteries and concrete floors

["PETER VANDERWAL" <peterv@peoplepc.com>]

Umm, read the WHOLE message.  Nothing is permeating the case except cold,
and plastic isn't immune to cold.



> That used to be a true statement, when battery cases were rubber and
pitch.
> They would seep acid and form a conductive layer with the concrete,
> resulting in a parasitic discharge. Today, with impermeable plastic cases,
> it doesn't matter.
>
> Rich
>
>
> ----- Original Message -----
> From: "VanDerWal, Peter" <vanderwp@fhu.disa.mil>
> To: <ev@listproc.sjsu.edu>
> Sent: Friday, March 30, 2001 4:32 PM
> Subject: Lead-Acid batteries and concrete floors
>
>
> > I'm sure we've all heard that Lead-Acid batteries will go dead quickly
if
> > you store them on concrete floods (i.e. in the garage).
> >
> > I'd pretty much assigned this to the "Old Wives" tale section since
nobody
> > could provide me with a credible explanation of why this was so or any
> > verifiable tests indicating it was true.
> >
> > Well I was going through some old magazines and I found a letter to the
> > editor that actually provided a reasonable sounding explanation of why
> this
> > happens.  I'm still not sure that they do go dead quicker on concrete,
> since
> > I've not heard of anybody testing it, but if they do this sounds like
why.
> >
> > The author pointed out that concrete floors tend to be colder than the
> > ambient temperature.  I've noticed this, I believe it's due to
> evaporation.
> >
> > Anyway with the battery sitting on the floor, the bottom of the battery
> will
> > be colder than the rest of it.  This causes temperature stratification
of
> > the electrolyte (different temperature layers).  The different
> temperatures
> > in the electrolyte leads to different specific gravity with the colder
> fluid
> > at the bottom having a lower specific gravity than the warmer fluid on
> top.
> > The different specific gravities will cause different voltage potentials
> > across the tops and bottoms of the plates.  With different voltage
> > potentials current will flow inside the battery and cause it to go dead
> > quicker.
> >
> > So what do you folks think, sound reasonable?
> >
> > P.S. If true I would suspect this has less effect on AGMs and Gel Cells.
> >
> >
> >
>
>