Today's Message Index:
----------------------
1. 01:47 AM - Re: Unshielded wire for mags? (Sacha)
2. 07:46 AM - Re: hypothetical question (Eric M. Jones)
3. 07:47 AM - Re: Landing gear warning trigger (user9253)
4. 08:57 AM - Re: Odyssey Batteries (Charles Brame)
5. 09:36 AM - Re: hypothetical question (user9253)
6. 11:05 AM - Re: EXP 2 Bus workaround (Fred Klein)
7. 11:06 AM - Re: Re: Odyssey Batteries (Robert L. Nuckolls, III)
8. 11:14 AM - Re: EXP 2 Bus workaround (Fred Klein)
9. 11:40 AM - Battery charger/maintainers (Robert L. Nuckolls, III)
10. 11:51 AM - EXP 2 Bus workaround (Fred Klein)
11. 12:50 PM - Re: Battery charger/maintainers (Tim Olson)
12. 04:42 PM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
13. 05:03 PM - Re: EXP 2 Bus workaround (Bill Bradburry)
14. 06:00 PM - Re: hypothetical question (user9253)
15. 06:19 PM - Alternator without a Battery (Thomas E Blejwas)
16. 08:36 PM - Re: EXP 2 Bus workaround (Fred Klein)
17. 11:14 PM - Re: Re: hypothetical question (Sacha)
Message 1
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| Subject: | Unshielded wire for mags? |
I believe that ignition wires on a Rotax are
not nearly so prone to radiate noise as those
on a legacy magneto. If you're not experiencing
a problem, then your requirements to limit noise
have not exceeded the limits established by potential
victims of noise. If it ain't broke, don't fix it.
Got it! Thanks!
Do not archive
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| Subject: | Re: hypothetical question |
Let's take a loop 4 meters in diameter and put 200A through it. The magnet field
created is about 0.63 Gauss. This is about the same as the Earth's magnetic
field itself. So I wouldn't be too worried about it.
It is telling that your friend was a Navy man. The US navy knows more about the
Earth's magnetic field than anyone else. Reading the published naval papers on
the subject is fascinating. They degauss ships hulls (Philadelphia Experiment!),
and even know how the pounding of rough seas changes the magnetism of ships'
hulls over time.
Aircraft steel tubes magnetize over time and compass compensation is periodically
figured in. But of course, the Earth's magnetic field and its consistency is
not great either. For local use this is okay. No pilot ever used a compass for
long distances.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=411199#411199
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| Subject: | Re: Landing gear warning trigger |
How about a RPM switch, all electronic with no moving parts?
Perhaps something like the attached untried circuit.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=411200#411200
Attachments:
http://forums.matronics.com//files/rpm_switch_502.pdf
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| Subject: | Re: Odyssey Batteries |
I couldn't find the original thread in the archives. So I hope this info
gets to the right builder.
I had a similar starting problem with a nearly new PC-680 a few years
ago, i.e., weak starts on my O-320, particularly on cold days. I also
was using a Battery Tender for charging. I called Odyssey to complain
and they said one is better off never charging than to use a Battery
Tender. Something about the Battery Tender not providing a high enough
initial charge resulting in the battery taking a lower than normal
voltage set. Odyssey sells a high dollar charger that they recommend.
However, based on info I got from Bob and others, I bought a Schumacher
1562 from WallMart for about $20. The Schumacher returned my PC-680 back
to life and it has started cold engines quickly for the last four years.
The Schumacher also rejuvenated a 10+ year old PC-680 and it has been
used to help start airplanes and autos all over the airport for several
years.
There is much in the archives regarding charging Odyssey batteries. The
Schumacher 1562 or equivalent is recommend in many threads.
Charlie Brame
RV-6A, N11CB
San Antonio
---------------------------------------------
Date: Oct 22, 2013
From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>
Subject: Re: Odyssey Batteries
At 07:21 PM 10/21/2013, you wrote:
Hi Bob,
I took one of your seminars a few years ago at Ohio State University
Airport and now I have my Wittman Tailwind flying in phase one testing.
The problem I am having with an Oddessey battery PC925 is that it will
not
start my Lycoming O-320 when it got to the mid 40s in temperature
overnight. I had the battery on a trickle charger overnight (Battery
Tender
brand) and it showed it had charged enough (green led on control unit).
This is the second Oddessey battery I have had in the Tailwind, I had
the
previous one replaced under warranty in May.
I need some guidance at troubleshooting this situation, when the battery
was first installed, it cranked the engine well. It has gotten
progressively slower at cranking despite being put on the trickle
charger.
Recently after it would not start early in the morning, I put it on the
trickle charger and tried to start it again after lunch. It did start
then,
just barely, and then I ran the engine for about 15 minutes to warm up
the
oil. The engine has a 60 amp alternator (Nippon Denso) and the buss
voltage
on my GRT EIS was 14.2-14.4 volts as the engine was running. After the
15
minute run, I shut off the engine and tried to restart after a couple of
minutes and the engine would not crank more than about 3 blades.
I realize that it is unlikely that I got bad battery to replace a bad
battery but I am not sure which component(s) to look at first. The
battery,
starter, wiring and alternator are all things that may be causing the
problem but what to check first?
Thanks for your help, this got a little longer than I intended.
I agree that the likelihood of two bad batteries in
a row is very low. It's likely that some COMBINATION
of effects (voltage drops) are adding up to sabotage
cranking performance.
It's very difficult to do quantitative analysis of
a cranking circuit using a starter as a load. Engine
compression strokes and other variables in mechanical
loads on starter make it impossible to use a digital
meter to make any measurements . . . and still difficult
with an analog instrument.
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| Subject: | Re: hypothetical question |
That reminds me of a story that a college professor, who was also an electrical
inspector, teaching the national electrical code told the class about an electrician
who did a very neat job. At the service entrance panel, he put all of
the white wires in one conduit and all of the black wires in another conduit.
It looked very nice and the inspector passed it. After the business moved into
the building, they noticed that the conduit was getting hot. They called
the inspector to complain about it. The inspector then realized that when both
white and black wires are in the same conduit, their magnetic fields cancel
each other out. But if they are in separate conduits, then the magnetic fields
are not cancelled. The rising and falling 60 Hz magnetic fields generate heat
in the metal conduit.
But that was alternating current. We are dealing with DC in an airplane. The
magnetic field around a wire carrying DC does not change unless the current
is changing. Albeit, the DC is not pure but has an AC ripple.
I agree that the magnetic field around a wire can affect a compass. The instructions
that come with a new compass say to twist the wires feeding the compass
light. But will magnetic fields cause mayhem with the radios?
The magnetic fields surrounding two wires, carrying opposite current, oppose
each other. I saw a film of a service panel whose load was faulted with hundreds
of amps. The parallel conductors were forced apart by the large magnetic
fields developed by the fault current. Since the magnetic fields of parallel
conductors oppose each other, that makes me think that they do not cancel each
other, at least not in the area right next to a wire.
Twisting of wires is what cancels induced currents in nearby conductors. Induced
current caused by one twisted wire is cancelled by the opposing induced current
caused by the other twisted wire.
Now consider a metal airplane where electrical currents from various loads all
flow though the airframe back to the source (alternator or battery). If anything
is going to cause interference, many currents flowing though the same conductor
will. Also consider a bundle of wires carrying positive current to various
loads. In that bundle are antenna coax and exterior lighting wires and
fuel pump wires and etc. But the radios work just fine. There could be reasons
to separate wires of opposite polarity. For instance, in a metal airplane,
the airframe can be used as one conductor. In a plastic airplane, there could
be mechanical situations where there is only room for one large conductor.
Or perhaps it is desired to keep always hot wires separated to prevent a short
circuit in case of a crash.
I am not disagreeing with anything that Bob said. Keeping positive and negative
wires together and twisted is good practice. I am asking if positive and
negative wires are separated in homebuilt aircraft, will there be significant
interference to radios?
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=411223#411223
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| Subject: | Re: EXP 2 Bus workaround |
On Oct 21, 2013, at 4:45 PM, Robert L. Nuckolls, III wrote:
> Still wondering about A/B ECU boards. Can you leave them
> powered up and simply select between A and B from the
> control panel. Does an ECU NOT selected draw the same
> current as the one presently selected?
Bob,
ECU manual states:
There are separate power inputs for the A and B controllers. If your
electrical system has a back up power bus you can connect the B
controller to it. Otherwise tie both A and B power inputs together.
Tracy Crook just emailed:
Yes, both controllers draw current when either one is selected, Also,
BOTH power inputs must be supplied with 12 volts when in operation.
Total Current draw is less than 1/2 amp.
If we proceed w/ an Engine Bus w/ alternate feed, it appears to me that
both A and B would best be tied together.
Fred
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| Subject: | Re: Odyssey Batteries |
At 10:57 AM 10/23/2013, you wrote:
I couldn't find the original thread in the archives. So I hope this
info gets to the right builder.
I had a similar starting problem with a nearly new PC-680 a few years
ago, i.e., weak starts on my O-320, particularly on cold days. I also
was using a Battery Tender for charging. I called Odyssey to complain
and they said one is better off never charging than to use a Battery
Tender. Something about the Battery Tender not providing a high
enough initial charge resulting in the battery taking a lower than
normal voltage set. Odyssey sells a high dollar charger that they
recommend. However, based on info I got from Bob and others, I bought
a Schumacher 1562 from WallMart for about $20. The Schumacher
returned my PC-680 back to life and it has started cold engines
quickly for the last four years. The Schumacher also rejuvenated a
10+ year old PC-680 and it has been used to help start airplanes and
autos all over the airport for several years.
There is much in the archives regarding charging Odyssey batteries.
The Schumacher 1562 or equivalent is recommend in many threads.
Good data. I had forgotten about those exchanges.
I'm not sure I understand the physics of the "low
initial charge" . . . I'll have to dig around in
the books on that. To be sure, the 1562 is probably
the best bargain out there.
Bruce, if your load tests at 200A drop the battery
to less than 10v, you might want to drop by Walmart
and pick up one of the Schumacher 1562 chargers. Walmart
is showing these on sale at the moment for $17.00.
http://tinyurl.com/m464b8d
I've owned several over the past 10+ years. Except for gross
failures, they've performed well on all size batteries
in my instrumentation herds.
A side note, a couple of 32 a.h. SVLA batteries
I've had for at least the past 10 years finally
gave up the ghost. Cells on the end of the stack
swelled up like a toad. These batteries were not
Odyssey products . . . both were Panasonic. The
last time I cap-checked them was about 4 years
ago and they were still turning in numbers
of 24+ a.h. at a 4 amp rate.
I don't think I've ever load-tested these batteries.
They were never used for cranking . . . only for
running portable instrumentation systems. The SLVA
can demonstrate exemplar performance.
Bob . . .
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| Subject: | Re: EXP 2 Bus workaround |
Bob...you asked about my fuel pumps and pressures...
The fuel pressure at idle is 38 psi; at wot it rises to 43 psi.
The pressure is controlled by a regulator which sits on what my guy calls a "fuel
log" which sets on the tops of the cylinders...I can provide photo if necessary.
Fred
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| Subject: | Battery charger/maintainers |
Odyssey claims that a Battery Tender (and I presume
Battery Minders with charge rates under 1A are incapable of
charging an Odyssey product due to "low initial charge
rates(?)"
I have long thought that a lead-acid product
of any capacity would eventually achieve a full
state of charge at any rate . . . as long as the
top-off voltage plateau was reached and held for
a substantial period of time . . . say 1 hour
or more.
I've never owned an Odyssey but I've used Battery-Tender
charger-maintainers for years on batteries up through
33 a.h. and found that the batteries took some time to
charge but cap-checked pretty much as expected. It's
not clear to me how would an Odyssey be that much different
than a Panasonic.
I found some test data I gathered on two wall-warts
(a Tender and a Minder) along with the Schumacher 1562
Emacs!
A Battery Minder I tested does not appear to accomplish a true
top-off cycle. On the other hand, the Battery Tender does seem to
conduct a top-off . . .
Emacs!
But the real value in $low$ charger/maintainers seems to be the
Schumacher 1562
Emacs!
The 1562 is about 2/3 the cost of the wall-warts, about twice
the "initial charge" rate and exhibits a robust/practical
implementation of a top-off cycle.
I have Battery Tenders in my shop . . .which seem to have served
me well . . . along with the 1562's for years.
Data shown above gives me pause to wonder if people do not make a
distinction between Battery Tenders and Battery Minders.
It's the Battery Minder that may be the bad-boy on the
street.
Bob . . .
Message 10
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| Subject: | EXP 2 Bus workaround |
Bob...this latest iteration of diagram is my effort, striving for
elegance, to incorporate your suggestions which I present as follows:
- Wire the engine bus via a diode feed from the 2, 11amp AUX circuits on
the EXP Bus; provide an alternate feed from the battery via an "Engine
Bus Alternate Feed Relay".
- Wire the endurance bus via a diode feed from a 7 amp circuit on the
EXP Bus; provide an alternate feed from the engine bus via an "Endurance
Bus Alternate Feed Relay".
- Regarding the re-wiring and re-labeling of some of the EXP Bus
rockers, I've deviated from your suggestions after considering the
following rationale and thinking about having a simple organization if
things go south:
Let the row of EXP Bus rockers serve for normal ops;
i.e., power up the ECU, the fuel injectors, and the coils using the 3
rockers furthest to the left, currently labeled
"I GN", "AUX", and "Clrnc Del"...(for my anticipated ops, clearance
delivery will be rarely used).
Let the space above the EXP Bus be for switches used
during emergencies; i.e., switch from fuel pump #1 to fuel pump #2;
switch engine bus to alternate feed, and endurance bus to alternate feed
(both feeds direct to battery, if EXP Bus or alternator go out.
- One battery and master contactor are shown, but I'm inclined to leave
open for now the option for dual batteries and rotating out one of them
periodically.
All comments most appreciated.
Fred
Message 11
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| Subject: | Re: Battery charger/maintainers |
Message 12
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| Subject: | Re: EXP 2 Bus workaround |
At 01:50 PM 10/23/2013, you wrote:
>Bob...this latest iteration of diagram is my effort, striving for
>elegance, to incorporate your suggestions which I present as follows:
>
>- Wire the engine bus via a diode feed from the 2, 11amp AUX
>circuits on the EXP Bus; provide an alternate feed from the battery
>via an "Engine Bus Alternate Feed Relay".
Okay, getting closer.
(1) Recommend you take the engine bus normal feedpath directly
from the main bus through the diode. A normal Engine ON/OFF
switch in this path seems to make sense see (6).
(2) add 30A maxi fuse in series with Engine Bus Alternate
Feed path and being engine power forward on 10AWG wire.
(3) Take E-Bus alternate feed directly from the battery on
it's own 7A fuse and 14AWG wire . . . 10A fuse if determined
necessary later.
(4) Go to solid state relays for e-bus and E-bus alternate
feeds, either Eric's or ours.
(5) Run #2 fuel pump from main bus through polyfuse and
EXP Bus switch.
(6) I see no value in having separate switches for
injectors, coils, normal pump or ECU feed. One switch
in normal feed path for normal engine ops, one switch
to control alternate feed path. When and why would you
ever operate one of these switches independently of
the others. Two ways to power engine . . . normal and
alternate.
(7) Suggest separate fuses for each injector and coil
assuming engine produces some useable power with any
one fuse open.
(8) Starter can control from main bus.
(9) Turn existing avionics bus into e-bus, convert
old avionics master into alternate feed path control
switch. Normal feed path comes from main bus through
diode.
(10) You speak to "room for breakers/fuses on panel"
suggest these be out of sight, of reach.
Bob . . .
Message 13
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| Subject: | EXP 2 Bus workaround |
Fred,
What is the switch "Clrnc Del" used for in the normal install? Is this a
second avionics master to use to get a clearance prior to starting the
engine??
Bill
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Fred
Klein
Sent: Wednesday, October 23, 2013 2:51 PM
Subject: AeroElectric-List: EXP 2 Bus workaround
Bob...this latest iteration of diagram is my effort, striving for elegance,
to incorporate your suggestions which I present as follows:
- Wire the engine bus via a diode feed from the 2, 11amp AUX circuits on the
EXP Bus; provide an alternate feed from the battery via an "Engine Bus
Alternate Feed Relay".
- Wire the endurance bus via a diode feed from a 7 amp circuit on the EXP
Bus; provide an alternate feed from the engine bus via an "Endurance Bus
Alternate Feed Relay".
- Regarding the re-wiring and re-labeling of some of the EXP Bus rockers,
I've deviated from your suggestions after considering the following
rationale and thinking about having a simple organization if things go
south:
Let the row of EXP Bus rockers serve for normal ops;
i.e., power up the ECU, the fuel injectors, and the coils using the 3
rockers furthest to the left, currently labeled
"I GN", "AUX", and "Clrnc Del"...(for my anticipated ops, clearance delivery
will be rarely used).
Let the space above the EXP Bus be for switches used
during emergencies; i.e., switch from fuel pump #1 to fuel pump #2; switch
engine bus to alternate feed, and endurance bus to alternate feed (both
feeds direct to battery, if EXP Bus or alternator go out.
- One battery and master contactor are shown, but I'm inclined to leave open
for now the option for dual batteries and rotating out one of them
periodically.
All comments most appreciated.
Fred
Message 14
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| Subject: | Re: hypothetical question |
I searched the internet for magnetic fields surrounding parallel conductors and
found out that if current is flowing in the opposite direction in two conductors,
the magnetic fields repel each other. The magnetic fields do not cancel
each other out. Instead they become distorted. The fields extend out less in
the direction of the other wire, and they extend out farther in the opposite
direction. Here is a picture of the distorted magnetic fields:
http://www.physchem.co.za/OB11-ele/graphics/magnetic1_f8.gif
>From this I conclude that running wires of opposite polarity close together and
in parallel does not reduce the magnetic field surrounding the wires. If devices
are sensitive to magnetic interference, they should be kept far away from
wires carrying large currents.
If the magnetic fields do not cancel, how to explain the phenomenon in my previous
post about conduit becoming hot when white and black AC wires are segregated,
but the conduit remains cool with both white and black wires contained within
one conduit? The current induced in the conduit by white wires is opposed
by current induced by black wires. Thus, no eddy current flows and the conduit
remains cool. But magnetic fields that surround each conductor are not cancelled.
A steady DC current will not induce voltages in adjacent wires.
A DC current with a large AC ripple can induce voltage in adjacent wires.
Twisting the positive and negative wires of a circuit together will minimize induced
voltage in adjacent wires. If the positive and negative antagonistic wires
are too big to be twisted together, and they are causing interference, then
they should be isolated.
Other views and comments are welcome.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=411276#411276
Message 15
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| Subject: | Alternator without a Battery |
In designing the electrical system for my Zenith Zodiac with a Viking engine, I
thought I would start with Z-19 and modify - add OVP for the alternator, a relay
to prevent run-on of the starter, and maybe more. Recent discussions on this
site about contactors and the Z-19 philosophy have me rethinking things.
Also, the Viking has an alternator that can run without a battery. I remember
driving an overloaded old Dodge Colt on a long evening trip (Christmas eve) and
having the headlights go dimmer and dimmer. Fortunately, I made it to a gas
station next to a motel, because the battery that had easily started the engine
4 hours earlier was very shorted. (I was able to get a used battery installed
on Christmas Day by a great farmer with a tow truck.). Why don't we worry
about this in airplanes? Shouldn't we be able to fully disconnect the battery
or batteries, if the alternator can run without a battery? Thanks.
Tom
Sent from my iPad
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| Subject: | Re: EXP 2 Bus workaround |
On Oct 23, 2013, at 5:03 PM, Bill Bradburry wrote:
> What is the switch =93Clrnc Del=94 used for in the normal install? Is
this a second avionics master to use to get a clearance prior to
starting the engine??
Bill...I suppose you could call it that...the Clearance Delivery is on a
"keep alive" 3 amp circuit w/ its own on/off switch intended for
communication w/ tower w/o turning on your whole panel prior to engine
start up...Fred
Message 17
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| Subject: | Re: hypothetical question |
>> I searched the internet for magnetic fields surrounding parallel conductors
and found out that if current is flowing in the opposite direction in two conductors,
the magnetic fields repel each other. The magnetic fields do not cancel
each other out. Instead they become distorted. The fields extend out less
in the direction of the other wire, and they extend out farther in the opposite
direction. Here is a picture of the distorted magnetic fields:
>> http://www.physchem.co.za/OB11-ele/graphics/magnetic1_f8.gif
Hi Joe
It's a question of scale. The fields do not cancel out exactly because the two
wires carrying current in opposite directions are not in exactly the same spot.
But If you move sufficiently far away from the pair of wires then the magnetic
field effectively cancels out. What does sufficiently far mean in this context?
Well if one goes through the calculations the critical distance d is the
distance between the center of the two conductors. So if they're kept very
close together (eg by twisting) then as long as you are at a distance D away from
the pair, where D is much greater than d, then the magnetic field becomes
very small. Typically d is of the order of a few millimeters so if you're eg
a meter away, then D is hundreds of times greater than d and the magnetic field
is for all intents and purposes zero.
Sacha
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