Today's Message Index:
----------------------
1. 09:56 AM - Re: EFIS Battery Back-up Power (Henry Trzeciakowski)
2. 10:46 AM - Re: Re: EFIS Battery Back-up Power (Ron Shannon)
3. 11:13 AM - Re: Re: EFIS Battery Back-up Power (John W Livingston)
4. 01:10 PM - Re: Re: EFIS Battery Back-up Power (John Morgensen)
5. 05:09 PM - Re: Re: Z-19 Item Clarification (Scott R. Shook)
6. 05:52 PM - Rotax capacitor (jtortho@aol.com)
7. 07:45 PM - Re: Rotax capacitor (Robert L. Nuckolls, III)
8. 09:56 PM - Re: Z-19 Item Clarification (ZuluZephyr)
Message 1
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| Subject: | Re: EFIS Battery Back-up Power |
Bob:
I'm planning to install a AFS 3400 with it's own internal battery
back-up...... fused it to my Main Bus..
How I visualize: main alternator goes off line, I kill the alternator via
the master switch, turn on the E-Bus alternator feed switch....
Since the Main Bus will be de-energized due to a failed alternator, I assume
that the EFIS will utilize it's internal battery to keep the EFIS
energized..... OR
is my thought process all wrong !!!
Do I need a seperate switch on my panel to turn the EFIS off, eventhough the
Main Bus is de-energized....
What would the wiring architect be in this case ??
Thanks
Hank
Message 2
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| Subject: | Re: EFIS Battery Back-up Power |
Hank,
If you have just one EFIS, it (or if you have two, the first one) should be
wired to the e-bus -- assuming you want to have the EFIS available during
endurance (battery only) flight ops -- as most of us would like to have.
If you have two EFIS's, you may want to shut one down during endurance ops,
and the second one would therefore be wired to the main bus. (If that second
EFIS already has an automatic internal battery, you may have to shut it down
manually even though it's on the main bus, to save that internal battery.)
This is the way my dual AFS-3400 EFIS system is wired.
The e-bus is normally fed from the main bus through a one-way diode. When
the alternator(s) fail, the e-bus alternate feed is turned ON which powers
the e-bus direct from the battery, i.e., not through the main battery
contactor. (For brief moment, the e-bus is then effectively fed from two
places: the battery upstream of the battery contactor, and the main bus,
from downstream of the battery contactor.) After the e-bus alternate feed
has been turned ON, you immediately turn the main battery contactor OFF, to
rapidly and positively shed those non-essential main bus loads. That's the
sequence (e-bus alt feed ON, then main battery contactor OFF) to keep the
e-bus powered and avoid rebooting things like your EFIS that are on the
e-bus when you shut down the main.
When the e-bus alternate feed is ON, and the main battery contactor and main
bus are OFF, the e-bus will not back feed the main bus because the diode
keeps current from flowing from the e-bus to the main bus.
I hope that helps explain the desired function and results.
Ron
On Sun, May 11, 2008 at 12:58 PM, Henry Trzeciakowski <hammer408@comcast.net>
wrote:
> hammer408@comcast.net>
>
> Bob:
>
> I'm planning to install a AFS 3400 with it's own internal battery
> back-up...... fused it to my Main Bus..
>
> How I visualize: main alternator goes off line, I kill the alternator via
> the master switch, turn on the E-Bus alternator feed switch....
> Since the Main Bus will be de-energized due to a failed alternator, I
> assume
> that the EFIS will utilize it's internal battery to keep the EFIS
> energized..... OR
> is my thought process all wrong !!!
>
> Do I need a seperate switch on my panel to turn the EFIS off, eventhough
> the
> Main Bus is de-energized....
>
> What would the wiring architect be in this case ??
>
> Thanks
>
> Hank
>
Message 3
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| Subject: | Re: EFIS Battery Back-up Power |
Why wouldn't you want to feed it directly from a battery bus with its own
switch? One wire, one switch, done. If you have two, EFISs then two wires,
two switches, done.
----- Original Message -----
From: "Henry Trzeciakowski" <hammer408@comcast.net>
Sent: Sunday, May 11, 2008 3:58 PM
Subject: AeroElectric-List: Re: EFIS Battery Back-up Power
> <hammer408@comcast.net>
>
> Bob:
>
> I'm planning to install a AFS 3400 with it's own internal battery
> back-up...... fused it to my Main Bus..
>
> How I visualize: main alternator goes off line, I kill the alternator via
> the master switch, turn on the E-Bus alternator feed switch....
> Since the Main Bus will be de-energized due to a failed alternator, I
> assume
> that the EFIS will utilize it's internal battery to keep the EFIS
> energized..... OR
> is my thought process all wrong !!!
>
> Do I need a seperate switch on my panel to turn the EFIS off, eventhough
> the
> Main Bus is de-energized....
>
> What would the wiring architect be in this case ??
>
> Thanks
>
> Hank
>
>
>
Message 4
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| Subject: | Re: EFIS Battery Back-up Power |
Hi Henry,
Henry Trzeciakowski wrote:
>
> Bob:
>
> I'm planning to install a AFS 3400 with it's own internal battery
> back-up...... fused it to my Main Bus..
>
> How I visualize: main alternator goes off line, I kill the alternator via
> the master switch, turn on the E-Bus alternator feed switch....
>
I am at the same stage in my 9A project and I think it is important to
be clear about the E-Bus terminology. You do not say what Z architecture
you are planning. I plan on a Z-13/8 strategy that has an SD-8 backup
alternator. I do NOT plan on an "endurance bus" like a traditional Z-11
architecture. In your scenario, killing the main alternator and
energizing the backup alternator will restore 8 amps of power to the
main bus. I expect the AFS 3500 and the Garmin GPS to stay up on their
internal batteries, if necessary, or the ships' battery while I switch
over. I will shed other loads with individual switches as necessary.
My only experience like this was a rented spam-can with my yoke mounted
Garmin. The first indication of an alternator failure came when the
Garmin complained, "external power lost". I have no idea how long the
alternator had been off line. Since then, I have discovered that the
Garmin 496 has all kinds of configurable alerts including a "low
voltage" that lets you set the threshold.
John
> Since the Main Bus will be de-energized due to a failed alternator, I assume
> that the EFIS will utilize it's internal battery to keep the EFIS
> energized..... OR
> is my thought process all wrong !!!
>
> Do I need a seperate switch on my panel to turn the EFIS off, eventhough the
> Main Bus is de-energized....
>
> What would the wiring architect be in this case ??
>
> Thanks
>
> Hank
>
>
>
Message 5
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| Subject: | Re: Z-19 Item Clarification |
The "requirement" I spoke of came about from an off-field incident in March
which Eggenfellner said that they will not support bridge rectifiers being
used for their engines.
Scott R. Shook
RV-7A (Building)
N696JS (Reserved)
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Mark
Sletten
Sent: Saturday, 10 May, 2008 19:58
Subject: AeroElectric-List: Re: Z-19 Item Clarification
<marknlisa@hometel.com>
sshook(at)cox.net wrote:
> I hear what you are saying with the 4P3T switch. I just don't see any
other alternatives to switching bus power while still staying within the
recommendations/requirements of Eggenfellner.
I've read the Eggenfellner install manual. There IS a schematic depicting
what the manual refers to as "one way to wire your system" using the switch
to which you refer. I couldn't find anything stating the switch as a
"requirement." As far as I can see, the ONLY benefit this switch provides is
the ability to switch between power supplies with a single switch.
Other than the drawing in the manual, which specific recommendation(s) from
Eggenfellner require you to incorporate a single point of failure in your
electrical system? Maybe a better question might be how has Eggenfellner
justified the recommendation(s) you feel compelled to follow?
sshook(at)cox.net wrote:
> Eventually, all roads in our redundant electrical systems lead to a single
point of failure - the power wire for the component we are powering. That
will always be a single point of failure as I do not know of many components
that have independent, redundant power sources.
Comparing a single, unbroken wire connected at either end with a switch
incorporating 12 external connecting points and a multitude of moving parts
manipulating several internal contacts is a bit of a stretch...
Even if you are convinced of the invincibility of the switch, what design
philosophy drives connecting both fuel pumps to a single pole of the switch?
Regards,
--------
Mark Sletten
Legacy FG N828LM
http://www.legacyfgbuilder.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=182437#182437
Message 6
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I have a new 0.5 farad capacitor sitting around.? It was left over from a step
sons car audio adventure.? I was thinking about using it for the capacitor in
my Rotax powered project. Since it will likely discharge after some shutdowns,?
This device would likely look like a short circuit, transiently?for every start
up.???is this a reasonable expectation??? Would this be too stressful for
the battery???I would guess the battery would try to charge it long before the
starter starts to crank. ?
Message 7
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| Subject: | Re: Rotax capacitor |
At 08:48 PM 5/11/2008 -0400, you wrote:
>I have a new 0.5 farad capacitor sitting around. It was left over from a
>step sons car audio adventure. I was thinking about using it for the
>capacitor in my Rotax powered project. Since it will likely discharge
>after some shutdowns, This device would likely look like a short circuit,
>transiently for every start up. is this a reasonable
>expectation? Would this be too stressful for the battery? I would guess
>the battery would try to charge it long before the starter starts to crank.
These things are 'tempting' . . . they offer a potential
for a very "quiet" system. However, your misgivings are
well founded. Capacitors this large present some system
dynamics at periods MUCH longer than those presented by
classic noise sources. Getting these puppies charged up
is not a trivial concern. Further, they boost the potential
for short but exceedingly large fault currents in case of
a short.
The battery and/or alternator are not at risk for damage.
I recommend that you stick with the smaller devices which
certainly perform to expectations and offer no special
risks.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 8
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| Subject: | Re: Z-19 Item Clarification |
Scott,
The failure that you mention was due to an incorrectly sized rectifier or diode
that was not designed to carry the load that was applied. Not because the basic
design is faulty. All designs have advantages and disadvantages.
Eggenfellner's design solves certain potential problems and creates others.
Ultimately, it is your plane and your risks. The trick is to make fully informed
decisions about the trade-offs in design and decide what your risk tolerance
is for the various design options.
Rocky Morrison
Sportsman / H6
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=182633#182633
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