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Date: Thu, 28 Jun 2007 10:07:42 -0400
From: Ernest Christley <echristley@nc.rr.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] BAttery Charger was: [FlyRotary] Amazing transformation
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Ed Anderson wrote:
> Hi Jim,
>  
>  Regarding the "new fangled" battery chargers, I also found out that 
> if you have a stone dead battery, mine will not charge it. I finally 
> used a trickle charger to get a small charge into the battery and then 
> the "new fangled" battery charger would then start charging.  But, 
> even then after charging at (I presume what it thought was an 
> excessive rate) would kick off line.
>  
I believe this has to do with them being switching mode power-supplies.  
The way I understand it, the supply has a resonant circuit (something 
like 10kHz).  That is passed through a transformer that is tapped in 
several places to give the various voltages.  Without some load, the 
resonant circuit won't ring, and you get no power.  To much draw and you 
kill the resonance again.  I was using one to do anodizing on aluminum.  
There was a definite sweet spot that the supply liked to be in.  Try to 
exceed two amps and the output would just drop off instead of increasing.

Monty, any idea how much current the derusting draws.  I used one of the 
$3 Harbor Freight multi-meters in series with my anodizing supply.  
It'll handle 10Amps.  If the current draw is low enough (which I suspect 
it would be if the process takes 24hours), you could use a wall-wart as 
a supply.