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

[Dean May]

I used a DC-DC converter to make 12V from my 24V system.  That way you can use the 24V alternator and still have 12V for stuff like that.
  ----- Original Message ----- 
  From: KeithHallsten 
  To: bobj at computer.org ; Velocity Aircraft Owners and Builders list 
  Sent: Sunday, January 23, 2005 11:49 PM
  Subject: Re: REFLECTOR: 24 volts vs. 12 volts -- Important 'Upside'


  Of course, all the reasonably-priced seat heaters are automotive, and therefore designed for 12 volts!

    ----- Original Message ----- 
    From: Bob Jackson 
    To: Velocity Aircraft Owners and Builders list 
    Sent: Sunday, January 23, 2005 7:22 PM
    Subject: RE: REFLECTOR: 24 volts vs. 12 volts -- Important 'Upside'


    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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