Re: Lead-Acid batteries and concrete floors

["Rich Weiss" <RichHeidi@TechHeadNet.com>]

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.
>
>
>