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

[Jim Agnew]

Correction, 1200W alternator

Jim

--- Wayne <wowens at darientel.net> wrote:

> Buying 24 V alternators and 24 V batteries is way more than twice as 
> expensive as 12 V stuff, if that matters.
> ----- Original Message ----- 
> From: "Jim Agnew" <jim_agnew_2 at yahoo.com>
> To: <bobj at computer.org>; "Velocity Aircraft Owners and Builders list" 
> <reflector at tvbf.org>
> Sent: Monday, January 24, 2005 8:47 AM
> Subject: RE: REFLECTOR: 24 volts vs. 12 volts -- Important 'Upside'
> 
> 
> > Not true, an alternator requires cooling for the heat produced in direct
> > relationship to the watts produced.  12V x 50A = 600 watts = 24V x 25A. 
> > If you
> > have the same amperage output at 24V you have a 120W alternator.
> >
> > Jim
> > --- Bob Jackson <bobj at computer.org> wrote:
> >
> >> 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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> >>
> >>
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> >
> > =====
> > James F. Agnew
> > Jim_Agnew_2 at Yahoo.Com
> > Tampa, FL
> > Velocity 173 Elite Aircraft Completed & Flying
> > _______________________________________________
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> >
> > 
> 
> 
> 


=====
James F. Agnew
Jim_Agnew_2 at Yahoo.Com
Tampa, FL
Velocity 173 Elite Aircraft Completed & Flying