From: BOBPAS26@aol.com
Message-ID: <c5.147ee691.28a2e1e9@aol.com>
Date: Wed, 8 Aug 2001 14:41:45 EDT
Subject: 12 vs 24 Volts
To: lancair.list@olsusa.com
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In a message dated 8/8/01 12:23:50 AM Eastern Daylight Time,  Micah Froese 
writes:

In planning for my panel, the question has come up whether to use 12 or 24 
volts.  For those who have already figured this one out, what is the answer. 
What are the pro and cons of each?
 
Micah, as with most things in this business, there is no "right" answer. 
We're using 24 volts in our IV-P's. The rationale was that we'd need the 
power for all the avionics and other things we might want to install. For 
alternators with the same power rating (100 amps in our case), you get twice 
as much power with the 24 volt sytem as with the 12 (Power = Amps x Volts). 
Having said that, I'm now having to add 24 to 12 volt converters to reduce 
voltage for some components that are not available in 24 volts--the MAC/RAC 
trim system is one example; some older radios are another. Adds complexity 
and weight! Further, the total power required for our pretty elaborate 
systems is not yet close to 100 amps, so right now, the 24 volt system seems 
to be overkill. One reason is that each generation of avionics (and even 
things like landing lights) tend to use less power--this is a trend that will 
almost certainly continue.

My bottom line recommendation would be to add up the power requirements for 
the equipment you intend to install and operate simultaneously--it's a bit of 
research, but you'll have to do it sooner or later. Allow a small amount for 
reserve, and see if you can live with the output of a 12 volt system. If you 
can, the benefits are weight savings, simplicity, and better availability of 
less expensive components.

Keep us posted on your project. Brother Ed from Fort Worth just placed a 
deposit on a Legacy. Would you be working in that neck of the woods? I'm 
trying to find a building and/or consulting partner for him--the best 
decision I made on this project was to build two IV-Ps in partnership with my 
neighbor.

Bob Pastusek
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