Today's Message Index:
----------------------
1. 04:47 AM - Re: Battery charging (Steve Kelly)
2. 05:06 AM - Re: Battery charging (user9253)
3. 08:12 AM - Re: Battery charging (racerjerry)
4. 11:15 AM - Finally I have a diagram (Ken Ryan)
5. 11:48 AM - Re: Battery charging (user9253)
6. 01:20 PM - Re: Battery charging (kenryan)
7. 01:53 PM - Re: Skipping the Endurance Bus (Robert L. Nuckolls, III)
8. 01:53 PM - Re: Re: How to Switch Five Devices (Robert L. Nuckolls, III)
9. 01:56 PM - Re: Skipping the Endurance Bus (Robert L. Nuckolls, III)
10. 03:06 PM - Re: Garmin GTX 335 Install nonsense(?) (Steve Stearns)
11. 03:46 PM - Re: Skipping the Endurance Bus (Art Zemon)
12. 04:07 PM - Re: Skipping the Endurance Bus (Art Zemon)
Message 1
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| Subject: | Re: Battery charging |
Some interesting ideas. What exactly is a schottky diode. Is it different than
a standard diode.
If the small battery was very low in charge how much current do you think could
flow in the 20 wire?
Steve
--------
Steve
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=459313#459313
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| Subject: | Re: Battery charging |
Yes, a Schottky diode is different than a standard diode, but I have no idea how
they are made. All I know is that they have half of the voltage drop.
Sorry, I do not know what the maximum charging current will be in a dead 9AH
battery. You could test it to find out.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=459314#459314
Message 3
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| Subject: | Re: Battery charging |
I guess that you can use Ohm's Law to find a resistance that would limit your maximum
charging rate. Let's say you want to limit the charging rate to 3A for
a #20 wire NOT in a bundle. With 14 volts, a 4.7 ohm resistance would do it.
Problem is resistor heat dissipation ability at these values. Such setup would
require a large 42 watt resistor (W=volts x amps). A 50 Watt 5 ohm resistor
would be the nearest commercial size. Google / Newark Electronics shows several
types in the $7 range.
When faced with similar problems, sometimes I use things like an old automotive
12 volt coil ignition resistor to limit current. Or, on the bench, I use different
wattage light bulbs; but remember that actual resistance changes somewhat
(increases), as the resistor heats up.
I am almost betting that you could use a small 3A diode at each end of your wire
to also serve as the "fuse" because the usual failure mode is that they explode
and pop open. But certain people here, who I highly respect, may yell at
me for suggesting this.
--------
Jerry King
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=459323#459323
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| Subject: | Finally I have a diagram |
Fellow Listers,
I finally have a diagram for my SuperSTOL / Rotax 914 electrical. I would
appreciate feedback as I am now at the implementation stage.
I have tried on several occasions to post the diagram along with an
accompanying .pdf file with text giving description, load analysis,
emergency procedures, etc. Unfortunately, each time my submission has been
rejected saying the attachments are too large, even though they are only
200 kilobytes combined. So I have had to come up with a work around.
You can view my work either by going to this page:
http://test-ken.com/superstol/electrical/index.html
or by simply downloading the two files directly:
Diagram: http://test-ken.com/images/SuperSTOL-Rotax914-
Electrical-Diagram.jpg
Text: http://test-ken.com/pdfs/SuperSTOL914ElectricalSystem.pdf
Thanks in advance for your feedback.
Ken Ryan
Message 5
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| Subject: | Re: Battery charging |
A lead acid battery is just about dead at 11 volts. If the charging voltage is
14, then only 3 volts has to be dropped. The internal resistance of the battery
will drop the voltage. There are too many variables to calculate the current.
I would just wire it without a resistor. Then discharge the battery and
go flying to see if a 7.5 amp fuse blows. If it does, increase the wire and
fuse size. Or do not run the battery down until it is almost dead. :D
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=459333#459333
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| Subject: | Re: Battery charging |
If you do as Joe suggests and the fuse blows, another option would be to run another
20 awg wire (if that would be easier).
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=459346#459346
Message 7
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| Subject: | Re: Skipping the Endurance Bus |
At 07:54 PM 8/7/2016, you wrote:
>On 8/7/2016 9:36 AM, Art Zemon wrote:
>>Folks,
>>
>>Please double-check my logic. I am designing the electrical system
>>for my BD-4C, which is a largely mechanical airplane. Totaling up
>>the typical current draw for everything except pitot heat, I am at
>>21 amps. Max draw is 28 amps. Since a B&C backup alternator can
>>supply 30 amps at cruise RPM, it seems that I don't need an
>>endurance bus at all. Instead, I would have the following emergency procedure:
>>
>>In Case of Alternator Failure
>>
>>Primary alternator OFF
>>Backup alternator ON
>>Pitot heat OFF (unless required for flight)
>>I do still need to add a couple of items to my equipment list but
>>neither draws much current: electronic ignition and a second com radio.
>>
>>Does this make sense? Am I missing something?
Do you have a battery contactor?
The e-bus structure eliminates the load
of a battery contactor during endurance
ops.
Bob . . .
Message 8
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| Subject: | Re: How to Switch Five Devices |
At 07:00 PM 8/7/2016, you wrote:
>
>How about putting all 5 wires into the barrel of one faston made for
>a larger wire size like 14 or 12 AWG? Use heat shrink for strain relief.
Multiple wires into an 'oversize' terminal
are perfectly acceptable. Probably won't need
heat shrink if you bring the insulation grip
down to support the bundle. See:
http://www.aeroelectric.com/articles/multiplewires/multiplewires.html
Bob . . .
Message 9
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| Subject: | Re: Skipping the Endurance Bus |
At 10:10 PM 8/7/2016, you wrote:
>Charlie,
>
>Good catch. Yes, this will be an IFR airplane. To the electrical
>load analysis that I have already done, I still need to add the
>second comm radio and the second EFIS screen, but those are minor
>loads compared to the pitot heat.
Have you ever shared a proposed disribution
diagram? It would be MUCH easier to for
electron-herders to convert words into
copper-reality when offering advise.
Bob . . .
Message 10
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| Subject: | Re: Garmin GTX 335 Install nonsense(?) |
Ira, Bob N. and the group:
I appreciate the reply. I do know the TSO installation instructions are
not obligatory but they also are the only installation instructions I
received.
I understand and appreciate your information regarding ground planes.
Where I am still interested in knowing more is the magnitude of the
differences between what they specify and what I have already installed.
Sure, bigger is better from an RF standpoint but would I or the FAA notice
the difference in a real life A/B comparison?
Bob, do you have any thoughts on this? I consider you one of the better
people out there to sift the meaningful theoretical benefits out from all
of the inconsequential ones...
Also, anyone want to render an opinion on all of the specified bonding? My
background leads me to conclude that "bonding" a 1/4 wave-radius ground
plane on my transponder antenna is a decidedly bad idea...
Steve Stearns
LongEz N45FC
Boulder/Longmont CO
Ira wrote:
*First, and most important, and Im sure you know that TSO installation
instructionsdo not apply to you.Theoretically, the benefit of ground planes
increases with size, in the limit,a ground (surface of the earth) antenna
ground plane which is the entire earthis optimal. However the benefit
decreases exponentially with size. Modern "active"gps antennae have a
ground plane which is a fraction of an inch on a sideand they are designed
to work just fine. It does have a ground plane, it isjust encapsulated
inside that plastic lump. Transponder transmitter antennaehave slightly
more critical requirements to optimize impedance load and
transmissionpattern. If your transponder performance was OK with existing
antenna,it will almost certainly work with the new one.*
Steve original wrote:
*I'll soon be installing a GTX335 transponder in my LongEz. The (stc)
install manual has some items I find curious related to the antennas.*
*While it does say if I'm replacing a different GTX transponder (I'm
replacing a 327) the existing transponder antenna is fine, it ALSO says
that the minimum radius for the transponder antenna ground plane is 12"!
Mine is 2.7" (1/4 wave at 1090 MHz). Anyone have any knowledge of what
they are trying to optimize?*
*Also it goes on to say the minimum radius for the gps antenna ground plane
is 7.5"! The gps antenna that goes with the GNS250XL has no ground plane
at all... Anyone have any idea what they are after here?*
*Also, the manual goes on and on about all the bonding required between
antenna ground planes, the avionics rack etc. My aircraft is a LongEz
(i.e. fiberglass) and I don't have any explicit "bonding" at all (though I
DO have very carefully planned and implemented power returns etc. In fact,
my transponder ground plane is encapsulated in fiberglass (except where it
is electrically connected to the coax connector).*
*My experience and existing knowledge tempts me to ignore all of the above
but, on the other hand, I'm still learning things that surprise me
everyday.*
*Can someone enlighten me as to the technical benefits to be had by
changing my existing configuration to be in line with what Garmin is
mandating in their installation manual?*
Message 11
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| Subject: | Re: Skipping the Endurance Bus |
Bob,
Thank you for mentioning the contactor. Yes, I will need one. No, I had not
gotten far enough through my design to remember it. And no, I had not
realized that the contactor uses significant power to stay closed. I'll add
it to the list.
I found White-Rodgers contactors at Aircraft Spruce and the data sheet
lists continuous power of 9 or 10 W which I figure to be approximately 0.75
A at 13.8 V. http://www.aircraftspruce.com/catalog/pdf/11-03161.pdf
Does that sound right for planning purposes?
-- Art Z.
On Mon, Aug 8, 2016 at 3:52 PM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 07:54 PM 8/7/2016, you wrote:
>
> On 8/7/2016 9:36 AM, Art Zemon wrote:
>
> Folks,
>
> Please double-check my logic. I am designing the electrical system for my
> BD-4C, which is a largely mechanical airplane. Totaling up the typical
> current draw for everything except pitot heat, I am at 21 amps. Max draw is
> 28 amps. Since a B&C backup alternator can supply 30 amps at cruise RPM, it
> seems that I don't need an endurance bus at all. Instead, I would have the
> following emergency procedure:
>
> In Case of Alternator Failure
>
> Primary alternator OFF Backup alternator ON Pitot heat OFF (unless
> required for flight)
> I do still need to add a couple of items to my equipment list but neither
> draws much current: electronic ignition and a second com radio.
>
> Does this make sense? Am I missing something?
>
> Do you have a battery contactor?
> The e-bus structure eliminates the load
> of a battery contactor during endurance
> ops.
>
>
> Bob . . .
>
--
http://CheerfulCurmudgeon.com/ <http://cheerfulcurmudgeon.com/>
*"If I am not for myself, who is for me? And if I am only for myself, what
am I? And if not now, when?" Hillel*
Message 12
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| Subject: | Re: Skipping the Endurance Bus |
Bob,
Here are the diagrams that I have so far:
https://drive.google.com/open?id=0BzOP2gb9_3RQUHpIMjNfa0NnQW8
The overview is basically my table-of-contents and it has the list of
devices with power requirements.
Cheers,
-- Art Z.
On Mon, Aug 8, 2016 at 3:55 PM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 10:10 PM 8/7/2016, you wrote:
>
> Charlie,
>
> Good catch. Yes, this will be an IFR airplane. To the electrical load
> analysis that I have already done, I still need to add the second comm
> radio and the second EFIS screen, but those are minor loads compared to the
> pitot heat.
>
>
> Have you ever shared a proposed disribution
> diagram? It would be MUCH easier to for
> electron-herders to convert words into
> copper-reality when offering advise.
>
>
> Bob . . .
>
--
http://CheerfulCurmudgeon.com/ <http://cheerfulcurmudgeon.com/>
*"If I am not for myself, who is for me? And if I am only for myself, what
am I? And if not now, when?" Hillel*
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