REFLECTOR: 24 volts vs. 12 volts -- Important 'Upside'

Bob Jackson bobj at computer.org
Sun Jan 23 21:22:43 CST 2005


An important 'upside' of 24v. is that it also effectively doubles an
alternator's current output capacity, usually with little, if any, increase
in weight.  Having extra amperage available will be important to us to use
for seat heaters (and possibly electrical heaters) for a warmer cabin during
long flights at high cruising (cold) altitudes.

Bob Jackson

      ----- Original Message -----
      From: Douglas Holub
      To: Velocity Aircraft Owners and Builders list
      Sent: 1/16/2005 9:11:08 PM
      Subject: Re: REFLECTOR: 24 volts vs. 12 volts


      If anyone is interested, I did some calculations: 30 feet of 2 AWG
wire weighs 6 lbs, and will drop .468 volts with a 100 amp load; 30 feet of
4 AWG wire weighs 3.78 lbs and will drop .373 volts with a 50 amp load.

      Doug
        ----- Original Message -----
        From: Joe
        To: Velocity Aircraft Owners and Builders list
        Sent: Sunday, January 16, 2005 10:13 PM
        Subject: Re: REFLECTOR: 24 volts vs. 12 volts


        Doug,
        No real downside if all the components you use are rated for 24v
(radios etc.)  You will need speed brake and trim actuators for 24v or build
a voltage divider into those circuits.  I was going to go 24v myself, but
since I am doing an auto conversion finding a 24v starter and/or 24v ECU
made it easier to stay 12v.

        Be careful with your statement about wires being smaller by 1/2,
wire size to current capability is not linear.  The wire length also has to
be included into wire sizing so that there is no more than a 0.5v drop on
12v circuits and 1.0v on 24v circuits.  AC 43-13 is a good source for sizing
wire in aircraft applications.

        One possible downside, if you want 110 vac power for say a laptop
computer, you might have a hard time finding a 24V inverter.

        Joe
          ----- Original Message -----
          From: Douglas Holub
          To: reflector at tvbf.org
          Sent: Sunday, January 16, 2005 10:37 PM
          Subject: REFLECTOR: 24 volts vs. 12 volts


          If I have a 24 volt system I'll use half the current so my wires
can be smaller by 1/2 and I'll save a pound or two. What's the downside?

          Doug


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