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Re: OT battery question

To: James Nazarian <jhn3@uakron.edu>
Subject: Re: OT battery question
From: Charles & Peggy Robinson <ccrobins@ktc.com>
Date: Tue, 18 Jan 2005 11:34:46 -0600
   All batteries have a max charge rate, despite the hype.  Charge a 
small battery at too high a current rate and see it heat up and buckle 
the plates, pop the vents and boil the electrolyte out.  You can treat 
the small AGM like a gel-cell, for the most part.

   My Toyota Prius has a 12 volt AGM in it as the aux battery so I did 
some research on them last fall.  A one amp, 12 volt wall-wart charger 
will do the job on yours, if you want to monitor the voltage after a few 
hours.  It ought to get the battery up to 80% charge in 7 hours, 
assuming it was flat to begin with.  Not a good idea to get it below 30% 
depth of charge (DOD) though.  Best charger choice is a "smart" charger 
that limits the current and has a "float" function.  Float is like 
trickle on a NiCD charger.  You can leave it connected all the time. 
Lots of info on the web.

   Cheers,

    CR

James Nazarian wrote:
> I know there are some people here that know way more about electricity that
> I do, and I have a few questions for those folks.  Feel free to reply off
> list if you wish.
> 
> I bought a small 12V 7Ah absorbed glass mat battery the other day and I have
> a couple of questions about it.
> 
> 1. The guy that sold it to me said you can't use a standard battery charger
> on it but that I should use a run of the mill 12V 1A wall transformer as a
> charger is that true?  Why?  
> 
> 2.  What is to keep it from overcharging or boiling the battery?
> 
> 3. If the battery is 7Ah and the charger is 1A will it take 7 hours to
> charge the battery?
> 
> Those are the questions that come to mind right now.  Thanks.
> 
> James Nazarian
> 71 MGBGT V8
> 71 MGB Tourer
> 87 BMW 325es




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