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Re: Battery not overcharging

To: thoward@sdcoe.k12.ca.us, triumphs@Autox.Team.Net
Subject: Re: Battery not overcharging
From: JAMES_S_WALLACE@HP-Canada-om1.om.hp.com
Date: Wed, 18 Feb 1998 09:56:10 -0500
     
     Point taken, but in my case I have five batteries to take care of, and 
     the one for the LBC is a big one that's more like 100 Cdn. bucks.  
     Plus, I have the ability to make a charger and thought that if a 
     kicking-around-the-garage regulator would work, the economies of doing 
     so would in fact be in my favour.
     So again, it seems that the regulator determines the battery's needs, 
     even if they're minimal, and sources the appropriate (low) current.
     So far, it still sounds like a pretty good solution, but my in-basket 
     is still flagging me so there may be more contrary news to come....
     
     Regards,
     Jim


______________________________ Reply Separator _________________________________
Subject: Re: Battery not overcharging
Author:  Non-HP-thoward (thoward@sdcoe.k12.ca.us) at HP-USA,mimegw5
Date:    17/02/98 10:43 PM

     
>     Why not? Any (constructive) comments? 
>     
>     Please respond in terms of electrons rather than molecules if 
>     possible, as I'm chemically-challenged but electronically-oriented.
     
Jim,
     
One can certainly build a charger to keep a car battery at peak during 
months of dis-use.
     
The only trick is to know a bit about the battery involved.   Such 
batteries have several paramiters that effect the state of charge.   
     
The capacity of the battery, the internal currents, and such.   Temperature 
can also play a roll.   As stated in other postings one wants to have just 
the right amount of current going into the battery to replace that charge 
that is lost.   This value will be different for different batteries and 
conditions.  
     
That leads to an electronic solution.   A power supply that will adjust its 
output to match the requirements of the current (no pun) conditions.
     
The typical requirements are in the range of 100-500 milliamps.   The 
voltage required to produce this value will change depending of the current 
state of charge, age, and condition of the battery.   
     
There are comercial products that address this requirement but those tend 
to be simple devices that are better than nothing, better than a standard
battery charger but less than a good constant-current power suppy can deliver.
     
Keep in mind that a brand new battery is about $30.00.   Money spent on 
maintaining an old battery so that it can be re-used some year/s down the 
road might just be a false economy.   This, and the need for a place to 
keep the "charging" battery, the possibility of a hydrogen gas buildup, a 
place to plug-in the charger to keep from tripping over the wires are all 
problems.   Just recycle the old one and go with fresh when required.
     
     
Thomas Howard
1972 Triumph GT6,
(& a good bit of USA iron)


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