Newsgroups: sci.electronics
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From: ejm@coyote.datalog.com (E.J. McKernan)
Subject: Re: Lead Acid batteries & Concrete?
Message-ID: <C5z2FI.4w6@coyote.datalog.com>
Organization: Datalog Consulting, Tucson, AZ
References: <1993Apr21.204556.21262@cronkite.ocis.temple.edu>
Date: Sat, 24 Apr 1993 05:11:40 GMT
Lines: 26

In article <1993Apr21.204556.21262@cronkite.ocis.temple.edu> camter28@astro.ocis.temple.edu (Carter Ames) writes:
>
>   I was just wondering one thing, actually two. ( I hope that this is the
>proper place to post this subject)
>
>  Why does a lead acid battery discharge and become dead (totally unuseable)
>when stored on a concrete floor?  
>  I decided to bring the battery in from the lawn mower and the motorcycle
>from the unheated garage this year, *to preserve them* and I just
>went to use them and noticed that not only do they not work, but 
>they act like the two terminals are shorted.  I asked a friend
>and he said that you should never do that, 'cause it ruins them,
>but he couldn't tell me why.
>

It's NOT the concrete floor that does it. The problem is that lead-acid
cells self discharge over time. Even high quality cells (Gates for instance)
will discharge 50-60% over a 3-5 month period of time. Non-sealed cells
self discharge even faster. If the battery was not completly charged
when left sitting, it probably discharged past the the point where cell
sulfiding occurs, which in many cases means a ruined battery.
-- 
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