Today's Message Index:
----------------------
1. 10:59 AM - Re: Re: Wire Harness Fabrication ()
2. 02:51 PM - Re: Positively Negative (-) ? (n1dw)
3. 06:04 PM - Re: Re: strobe noise (Bernie Willis)
4. 07:08 PM - Re: strobe noise (user9253)
Message 1
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| Subject: | Re: Wire Harness Fabrication |
>From my experience
Leave extra wire at the end of where ever you are routing your wire for a
service loop and just in case, 4 or 5 feet is not excessive.
Make sure you have enough space, the bundles are much thicker than I
imagined at the start.
Put in 4,5 or even 6 extra wires just in case you want to reposition
something or decide on something new
I printed labels on paper and used clear heatshrink to seal the labels onto
the wire, shorter intervals between labels at the termination and larger
spacing in the middle of the run, this worked well
Don't be discouraged if it looks messy while you are working, it looks much
better after you tidy up and lace or tie your bundles.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
<owner-aeroelectric-list-server@matronics.com> On Behalf Of jsajpf
Sent: October 26, 2020 8:47 PM
Subject: AeroElectric-List: Re: Wire Harness Fabrication
--> <john.friday_adis@sbcglobal.net>
If you haven't run across the Dark Aero project yet, recommend having a look
at their Knowledge Base resource they make available. The Avionics
Spreadsheet Tool is a pretty impressive collection of info to aid in
planning a build. Found here: https://www.darkaero.com/knowledge/avionics/.
They have a video on their YouTube channel explaining some of their routing
layout techniques (i.e. a variation on the butcher paper theme).
The FAA has some guidance available in the form of a Job Aid with numerous
pictures and illustrations, meant primarily for large transport category
aircraft.
https://www.faa.gov/training_testing/training/air_training_program/job_aids/
And this resource from Australia has proven useful; its kind of an updated
Chpater 11 of AC 43.13-1B:
https://www.casa.gov.au/standard-page/ac-21-99-aircraft-wiring-and-bonding
Best,
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=498965#498965
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Message 2
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| Subject: | Positively Negative (-) ? |
This comment may not be relevant as I am not aware of the engine
installation. I have a single alternator dual battery configuration with
batteries aft and 2 AWG cables between the batteries and firewall
connection. From the latter connection, I feed the main bus and an e-bus
via a diode. I also have direct switched feeds from the batteries to the
e-bus. I have an electrically dependent automotive fuel injected conversion
powerplant.
I found that when attempting to start on one battery, I could not get a
reliable start. But when I switched to the second battery directly to the
e-bus, no starting problem. My conclusion is that the voltage drop while
cranking the engine was sufficient to cause the ignition system to not
operate reliably. This may have been due to the 9-10v cranking voltage
drop in in addition to the up to 1v drop across the diode. It is my
understanding that most ignition systems need 10v to operate reliably.
My current process to start the engine is to crank on the A battery while
feeding the B battery directly to the e-bus.
Again, don't know if this is relevant to this discussion.
Regards, Doug Windhorn
From: owner-aeroelectric-list-server@matronics.com
<owner-aeroelectric-list-server@matronics.com> On Behalf Of Robert L.
Nuckolls, III
Sent: Sunday, October 25, 2020 11:32 AM
Subject: Re: AeroElectric-List: Positively Negative (-) ?
At 06:48 AM 10/25/2020, you wrote:
<mailto:bionicad@hotmail.com> >
After reading this article: https://www.kitplanes.com/positively-negative/
I ran a positive and a negative 2awg conductor from the back (battery) of my
RV10 to the front. I missed the point where I had to calculate the total
cable length for the intermittent starting process..
Igor, please don't do this . . .
There is no foundation in physics or practice that
justifies this.
Yes, the proposed 'upgrades' have some 'advantage'
but too small to observe and difficult to measure.
See Figure Z-15 for grounding architectures
that have successful track records going back
nearly a century.
This leaves me with approx. 28ft total 2awg wire length installed.
-2awg (+) wire from battery to starter and 2awg (-) wire from the engine
block to the firewall and from there to the battery. The only airframe
negative is grounded at the firewall.
My question is: how much current does the B&C starter draw inrush and
continuous to determine whether the 28ft 2awg wire can handle it without too
much of voltage drop -thus hurting the starter's performance?
"Too much voltage drop" is un-quantified.
Are you having problems cranking the engine?
"Hurting starter performance" is also
un-quantified. No starter EVER expects
to see 12v in any vehicle. It's a given
that internal resistance of the battery
added to cranking path resistance will
deliver 9-10 volts to the starter. Modern
starters not withstanding deliver much
better performance than the legacy
tractor starters fitted to most of
the Lycomings in the years before
B&C and they got the engine running
un spite of engine driven fuel pumps,
manual primer pumps, magnetos with
impulse couplers, etc. In fact, if
was skilled at getting the
variables corraled, the engine could
be started by hand.
The quantum jump in modern starter performance
pretty much eliminates starters as
a root cause for poor cranking. Adding
wires in the manner suggested in the article
is at best, a band-aid on some more
fundamental problem.
Bob . . .
Message 3
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| Subject: | Re: strobe noise |
Continuing to work the strobe noise dilemma in the old Bonanza. The latest was
an awg 8 wire from an alternator mounting bolt to the negative post of the battery..Perhaps
the strobe noise is a little less but the wig wag wing lights are
just as noisy. The strobes ground to the grounding forest but the wig wags
are to the airframe. I think my next step is to move their ground to the grounding
forest. This may have nothing to do with the problem but perhaps is worth
mentioning. The original landing lights were PAR 46 incandescent. I made
a minor alteration and changed them to PAR 36 LED with no noise. The noise occurred
when I went to PAR 46 LED. I used the same wiring for both size LED Bulbs.
Perhaps the extra current for the larger light is part of the problem.
Again the noise doesnt change with alternator speed or radio on or off.
Please continue to share your ideas.
Thanks,
Bernie
> On Oct 14, 2020, at 09:04, user9253 <fransew@gmail.com> wrote:
>
>
> Usually the negative wire needs to be the same size as the positive wire. The
exception is when
> the negative current has another path to ground, for instance through mounting
brackets.
>
> --------
> Joe Gores
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=498821#498821
>
>
>
>
>
>
>
>
>
Message 4
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| Subject: | Re: strobe noise |
Try increasing size of the alternator "B" lead to see if that helps.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=498973#498973
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