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                           AeroElectric-List Digest Archive
                                      ---
                     Total Messages Posted Sun 09/17/23: 2
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Today's Message Index:
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     1. 05:10 AM - Re: New kid on the block in automatic chargers  (racerjerry)
     2. 11:10 AM - Re: Re: New kid on the block in automatic chargers  (Robert L. Nuckolls, III)
 
 
 
________________________________  Message 1  _____________________________________


Time: 05:10:06 AM PST US
Subject: AeroElectric-List: Re: New kid on the block in automatic chargers
From: "racerjerry" <gnking2@verizon.net>


My favorite trick for limiting the charging rate on small  motorcycle type lead-acid
batteries is to connect the charger in series with an old automotive ignition
coil ballast resistor.  These resistors were used long ago before fuel injection
and electronic ignition became commonplace; but I see that they are still
available as an aftermarket item.

--------
Jerry King


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=511433#511433


________________________________  Message 2  _____________________________________


Time: 11:10:50 AM PST US
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Subject: Re: AeroElectric-List: Re: New kid on the block in automatic   chargers

At 07:09 AM 9/17/2023, you wrote:
>
>My favorite trick for limiting the charging rate on 
>small  motorcycle type lead-acid batteries is to connect the charger 
>in series with an old automotive ignition coil ballast 
>resistor.  These resistors were used long ago before fuel injection 
>and electronic ignition became commonplace; but I see that they are 
>still available as an aftermarket item.

   Yeah, those popped up in early days of transition
   from 6 to 12 volt cars. The resistor offered a way
   to run 6v coils in 12v cars. Further, by adding an
   extra contact inside the starter contact, this resistor
   could be shorted out during cranking to improve
   spark intensity during the cranking 'brownout'.

   An additional benefit of added resistor was
   to decrease charging time for magnetizing the ignition
   coil.  The time constant for an LR circuit is

          L
   t = -------
        Rc + Rb

   L is the primary inductance (constant)

   Rc is resistance of coil primary winding

   Rb is resistance of the ballast resistor

   In the 'run' condition, Rb is in operation
   which halves the rise time of current in
   the primary coil after points close.


   Bob . . .

                    ////
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    In the interest of creative evolution
    of the-best-we-know-how-to-do based
    on physics and good practice.

 

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