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nuckolls.bob(at)aeroelect
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 Posted: Mon May 18, 2009 6:25 pm Post subject: 12 Volt vs. 24 Volt |
 |
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At 08:06 PM 5/18/2009, you wrote:
<rtitsworth(at)mindspring.com>
If you're thinking heated prop, Elec air conditioning, Elec cabin heat,
heated seals, or other high-energy goodies, then a 24V system/alternator
offers twice the "power" for roughly the same system weight as a 12v
alternator. It's not the (potential) smaller wire savings that is
significant/relevant, rather it's twice the available power from the same
weight alternator, contactors, etc (i.e. the heavy items).
Which reminds me of advice I've offered in
years past but worth repeating again: The
first task for crafting your electrical system
is to craft a load analysis. If your maximum
cruising load is expected to exceed 1000 watts,
then PERHAPS a 28v system is called for.
In the past 20 years, I've been directly
involved in crafting only two 28v OBAM
aircraft. One was a LongEz where the owner
wanted to fly a lot in the northern climes.
A 100 amp, 28v alternator was included to
over about 200 watts of energy to run the
airplane . . . and 2,000 watts for toe
heaters!
The other was a Lancair IV with electrically
driven air conditioning. But even this system
pretty low duty cycle. For all the weight, cost
and complexity of an air conditioner, it operates
an average of 30 minutes per flight cycle in
hot weather. The rest of the time, it was dead
weight.
The 14/28 debate really isn't a debate if you
need the energy. But with continuing advances
in LED lighting, LCD under glass instruments,
etc the energy required to run the vast majority
of the OBAM fleet has been going down. It's a
rare airplane that needs more than 500 watts
(40A at 14v) continuous running loads. Up to
twice that load is easily carried by modern
automotive alternators. There are a lot of
cars coming off the line these days with 100+
amp alternators on them.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
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joemotis(at)gmail.com
Guest
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| Posted: Mon May 18, 2009 7:38 pm Post subject: 12 Volt vs. 24 Volt |
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As more and varied low current draw devices become available, do you see PV in the equation?
On Mon, May 18, 2009 at 7:23 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
[quote]--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>
At 08:06 PM 5/18/2009, you wrote:
--> AeroElectric-List message posted by: "Rick Titsworth" <rtitsworth(at)mindspring.com (rtitsworth(at)mindspring.com)>
If you're thinking heated prop, Elec air conditioning, Elec cabin heat,
heated seals, or other high-energy goodies, then a 24V system/alternator
offers twice the "power" for roughly the same system weight as a 12v
alternator. It's not the (potential) smaller wire savings that is
significant/relevant, rather it's twice the available power from the same
weight alternator, contactors, etc (i.e. the heavy items).
Which reminds me of advice I've offered in
years past but worth repeating again: The
first task for crafting your electrical system
is to craft a load analysis. If your maximum
cruising load is expected to exceed 1000 watts,
then PERHAPS a 28v system is called for.
In the past 20 years, I've been directly
involved in crafting only two 28v OBAM
aircraft. One was a LongEz where the owner
wanted to fly a lot in the northern climes.
A 100 amp, 28v alternator was included to
over about 200 watts of energy to run the
airplane . . . and 2,000 watts for toe
heaters!
The other was a Lancair IV with electrically
driven air conditioning. But even this system
pretty low duty cycle. For all the weight, cost
and complexity of an air conditioner, it operates
an average of 30 minutes per flight cycle in
hot weather. The rest of the time, it was dead
weight.
The 14/28 debate really isn't a debate if you
need the energy. But with continuing advances
in LED lighting, LCD under glass instruments,
etc the energy required to run the vast majority
of the OBAM fleet has been going down. It's a
rare airplane that needs more than 500 watts
(40A at 14v) continuous running loads. Up to
twice that load is easily carried by modern
automotive alternators. There are a lot of
cars coming off the line these days with 100+
amp alternators on them.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
owse
s.com/Navigator?AeroElectric-List" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
ronics.com/" target="_blank">http://forums.matronics.com
Matt Dralle, List Admin.
=====
[b]
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Tue May 19, 2009 5:37 am Post subject: 12 Volt vs. 24 Volt |
|
|
At 10:32 PM 5/18/2009, you wrote:
| Quote: |
As more and varied low current draw devices become available, do you
see PV in the equation?
|
Photovoltaic? Not soon. The power/weight ratio for PV
generators is not attractive, yet. Yeah, there are some
demonstration projects out there.
http://www.greenjobs.com/Public/IndustryNews/inews04432.htm
. . . but if you're anything like me, flying at night
and on cloudy days is not an option I'd want to give
up.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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thorn(at)starflight.aero
Guest
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| Posted: Tue May 19, 2009 6:08 am Post subject: 12 Volt vs. 24 Volt |
|
|
Thanks,
Allyson
On May 18, 2009, at 9:23 PM, "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com
> wrote:
| Quote: |
>
At 08:06 PM 5/18/2009, you wrote:
>
If you're thinking heated prop, Elec air conditioning, Elec cabin
heat,
heated seals, or other high-energy goodies, then a 24V system/
alternator
offers twice the "power" for roughly the same system weight as a 12v
alternator. It's not the (potential) smaller wire savings that is
significant/relevant, rather it's twice the available power from the
same
weight alternator, contactors, etc (i.e. the heavy items).
Which reminds me of advice I've offered in
years past but worth repeating again: The
first task for crafting your electrical system
is to craft a load analysis. If your maximum
cruising load is expected to exceed 1000 watts,
then PERHAPS a 28v system is called for.
In the past 20 years, I've been directly
involved in crafting only two 28v OBAM
aircraft. One was a LongEz where the owner
wanted to fly a lot in the northern climes.
A 100 amp, 28v alternator was included to
over about 200 watts of energy to run the
airplane . . . and 2,000 watts for toe
heaters!
The other was a Lancair IV with electrically
driven air conditioning. But even this system
pretty low duty cycle. For all the weight, cost
and complexity of an air conditioner, it operates
an average of 30 minutes per flight cycle in
hot weather. The rest of the time, it was dead
weight.
The 14/28 debate really isn't a debate if you
need the energy. But with continuing advances
in LED lighting, LCD under glass instruments,
etc the energy required to run the vast majority
of the OBAM fleet has been going down. It's a
rare airplane that needs more than 500 watts
(40A at 14v) continuous running loads. Up to
twice that load is easily carried by modern
automotive alternators. There are a lot of
cars coming off the line these days with 100+
amp alternators on them.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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