REFLECTOR: 12 Volt .vs. 24 Volt

[lawrence epstein]

The advantage is V=IR or I=V/R. In other words, if you double the Voltage, you half the required current for a particular task. this is most evident with high current items like the , starter, landing lights, speedbrake motor and things like electric anti-ice, etc.  Using a 24 volt system allows you to use a lower capacity alternator as well as smaller gauge wire and lower rated fuses/circuit breakers (all less expensive than the higher gauge/capacity counterparts)
It is also easy to use a mixed system where you use the 24 volt system for the items above, but (using TSO'd components) you can easily provide a 12v bus for items that need that voltage.

Larry Epstein

> From: bwolf1 at tds.net
> To: reflector at tvbf.org
> Date: Sun, 17 May 2009 15:31:41 -0400
> Subject: REFLECTOR: 12 Volt .vs. 24 Volt
> 
> All
> 
> Almost every time I start a new phase in the building process of my  
> XLRG-5, I am a bit slowed because I have not decided on an electrical  
> system. I would be interested in hearing the opinions of the  
> collective as to any advantage of a 24 volt system.  It would save  
> some weight with smaller gauge wire, but I think the weight savings in  
> negligible.  Other than that, I can't think of an advantage.  One  
> major sticking point in the decision making process is Cessna, Cirrus,  
> and others.  Are they putting 28 volt systems in their new airplanes?   
> If so, one would assume there are good reasons for doing so.  Does any  
> one know what those good reasons might be?  I've got to get off this  
> fence and get on with my project!!
> 
> BTW I plan on a robust electrical system (probably 2 alternators, 1  
> battery) to support a fairly sophisticated IFR panel with sufficient  
> redundancy for serious weather flying.
> 
> Thanks.....Brooke 
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