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paul.r.kuntz(at)gmail.com
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 Posted: Thu Aug 08, 2013 8:43 pm Post subject: Rotax 912 UL alternator drop-out |
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I have a homebuilt Pipistrel Sinus with a Rotax 912 UL that I flew to Oshkosh and back last week. The panel has a dual Dynon Skyview display with two-axis autopilot, plus radio and transponder. The total electrical load with everything running is 7 to 8 amps. Occasionally it can go to 10 amps if I'm charging cell phone and iPad en route. I'm pretty confident that I have the electrical system wired so that the ammeter is measuring the total electrical load.
The alternator dropped out once on the outbound trip, but came back after removing the iPad charging load. The symptom was a voltage drop from 13.8 volts to 12.5 volts. On preflight the voltage may read that high for a minute or so on a freshly-charged battery, but it quickly drops to 12.2 or 12.1 volts. In flight, the voltage would drop to 12.5 volts and stay there for several minutes. I would think that if the alternator had failed, I'd see the voltage drop to the same 12.1 volts that I see on preflight, and keep dropping slowly. I can't see why it would drop to 12.5 volts and stay there, unless the voltage regulator is failing in a way that I'm not familiar with.
The alternator dropped out (same symptoms) a few times on the trip back, but by reducing the load to 3 amps (one Skyview display, radio and transponder), it stayed on line except for awhile when it seemed that the mid-day sun shining on the dashboard was adding extra heat behind the panel. That time we brought it back by directing cool air from a fresh air vent forward toward the spot where the voltage regulator is mounted inside the cabin on the back side of the firewall.
So the problem seems to be heat-related. Does this make sense? The Rotax alternator is supposed to be rated for 18 amps, and able to handle a steady load of 14 amps easily. Does the Ducati regulator have a thermal self-protect cutout? Do I perhaps have a regulator that is ready to fail completely, or should I just put an avionics cooling fan behind the panel to get the air moving?Any other ideas?
Regards,
Paul Kuntz
[quote][b]
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dgraham7(at)TWCNY.RR.COM
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| Posted: Fri Aug 09, 2013 3:42 am Post subject: Rotax 912 UL alternator drop-out |
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Hey, read this.
Regards,
Damien
Sent from my iPad
On Aug 9, 2013, at 12:42 AM, Paul Kuntz <paul.r.kuntz(at)gmail.com (paul.r.kuntz(at)gmail.com)> wrote:
[quote]I have a homebuilt Pipistrel Sinus with a Rotax 912 UL that I flew to Oshkosh and back last week. The panel has a dual Dynon Skyview display with two-axis autopilot, plus radio and transponder. The total electrical load with everything running is 7 to 8 amps. Occasionally it can go to 10 amps if I'm charging cell phone and iPad en route. I'm pretty confident that I have the electrical system wired so that the ammeter is measuring the total electrical load.
The alternator dropped out once on the outbound trip, but came back after removing the iPad charging load. The symptom was a voltage drop from 13.8 volts to 12.5 volts. On preflight the voltage may read that high for a minute or so on a freshly-charged battery, but it quickly drops to 12.2 or 12.1 volts. In flight, the voltage would drop to 12.5 volts and stay there for several minutes. I would think that if the alternator had failed, I'd see the voltage drop to the same 12.1 volts that I see on preflight, and keep dropping slowly. I can't see why it would drop to 12.5 volts and stay there, unless the voltage regulator is failing in a way that I'm not familiar with.
The alternator dropped out (same symptoms) a few times on the trip back, but by reducing the load to 3 amps (one Skyview display, radio and transponder), it stayed on line except for awhile when it seemed that the mid-day sun shining on the dashboard was adding extra heat behind the panel. That time we brought it back by directing cool air from a fresh air vent forward toward the spot where the voltage regulator is mounted inside the cabin on the back side of the firewall.
So the problem seems to be heat-related. Does this make sense? The Rotax alternator is supposed to be rated for 18 amps, and able to handle a steady load of 14 amps easily. Does the Ducati regulator have a thermal self-protect cutout? Do I perhaps have a regulator that is ready to fail completely, or should I just put an avionics cooling fan behind the panel to get the air moving?Any other ideas?
Regards,
Paul Kuntz
[b]
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BARRY CHECK 6
Joined: 15 Mar 2011
Posts: 738
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| Posted: Fri Aug 09, 2013 4:33 am Post subject: Rotax 912 UL alternator drop-out |
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Hi Paul:
Sounds like you have a gorgeous plane.
For a standard and 99.976% of the different types of batteries to charge you MUST keep the charge voltage between 13.8 to 14.2 VDC. Over 14.2 you start to overheat the battery. Under 13.8 the voltage is not there to remove the oxides for the battery plates.
One thing you mentioned perked my ears up - Dual axis autopilot... Now, that is probably the highest single current draw in your plane. Were you in A/P? Did you hit and air bumps? When an A/P has to recover from an air pump the instantaneous current draw goes up sharply. The power is or should be drawn from the battery followed by the replenishment by the charging system. Now, from my reading Rotax has the worst charging system next to Banlon sock rubbing on a wool carpet. But, I would check things such as you mentioned - COOLING - It may be easier to install a small air scoop with a hose or fans (caution- fans have their own current draw) to blow air directly onto the ACU. This is done in quite a few planes where forced air is blown directly onto the radio stack. The other thing I would check is wire gauge size. First off it should be 'Teflon' wire and it is always better to go UP in size. IF the alternator output is rated at 18 Amps the wire size should be no smaller than a 10 AWG and I would use 8 AWG. This is one case where bigger is better. And weight for such a short run is not an issue. That takes care of the charging requirements. You will have to address the wire sizes for the other electronic equipment. Keep in mind Teflon wires allow you to use smaller gauge sizes. But, HEAT, forces you to use larger gauge sizes.
From my Rotax readings - I would say Rotax is not supplying the advertized 18 Amps and it is not in a smooth DC waveform output.
Power Reduction Sequence:
Least needed First -
Cell Phone 
iPad
LIGHTS
A/P
Second Comm Radio
Second Nav/GPS
The only reasion I mention this is because an IPad under charge would be only about 1 Amp for a dead battery. A cell phone under charge - 0.1 Amp (100 mA). The other items sure can have high draw.
Another thought - How warm/hot is the firewall? IF the firewall is warm/hot or if there is dead air under the dash, you may benefit by placing the ACU on stanchions or placing it on a heat sink. A TRICK that I did on my plane: I covered the glareshield with black speaker carpet. This created a heat shield for radio stack by creating a low heat transfer barrier, aluminum and thin leatherette passes the sun's rays/heat very easily. It also added some class to the plane.
Good luck,
Barry
On Fri, Aug 9, 2013 at 12:42 AM, Paul Kuntz <paul.r.kuntz(at)gmail.com (paul.r.kuntz(at)gmail.com)> wrote:
[quote]I have a homebuilt Pipistrel Sinus with a Rotax 912 UL that I flew to Oshkosh and back last week. The panel has a dual Dynon Skyview display with two-axis autopilot, plus radio and transponder. The total electrical load with everything running is 7 to 8 amps. Occasionally it can go to 10 amps if I'm charging cell phone and iPad en route. I'm pretty confident that I have the electrical system wired so that the ammeter is measuring the total electrical load.
The alternator dropped out once on the outbound trip, but came back after removing the iPad charging load. The symptom was a voltage drop from 13.8 volts to 12.5 volts. On preflight the voltage may read that high for a minute or so on a freshly-charged battery, but it quickly drops to 12.2 or 12.1 volts. In flight, the voltage would drop to 12.5 volts and stay there for several minutes. I would think that if the alternator had failed, I'd see the voltage drop to the same 12.1 volts that I see on preflight, and keep dropping slowly. I can't see why it would drop to 12.5 volts and stay there, unless the voltage regulator is failing in a way that I'm not familiar with.
The alternator dropped out (same symptoms) a few times on the trip back, but by reducing the load to 3 amps (one Skyview display, radio and transponder), it stayed on line except for awhile when it seemed that the mid-day sun shining on the dashboard was adding extra heat behind the panel. That time we brought it back by directing cool air from a fresh air vent forward toward the spot where the voltage regulator is mounted inside the cabin on the back side of the firewall.
So the problem seems to be heat-related. Does this make sense? The Rotax alternator is supposed to be rated for 18 amps, and able to handle a steady load of 14 amps easily. Does the Ducati regulator have a thermal self-protect cutout? Do I perhaps have a regulator that is ready to fail completely, or should I just put an avionics cooling fan behind the panel to get the air moving?Any other ideas?
Regards,
Paul Kuntz
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ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
tp://forums.matronics.com
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Roger Lee
Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.
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| Posted: Fri Aug 09, 2013 6:07 am Post subject: Re: Rotax 912 UL alternator drop-out |
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Your system can handle 16 amp continuous load. With this jumping around like this my first pick for the problem is a poor ground. Most of the time on the LSA I work on I find loose grounds. They may be hand tight, but wrench loose. Put a wrench on all your grounds. I have found that this solves 80% of the electrical issues on LSA especially where composite aircraft are concerned. Depending on where you live corrosion can be a factor too. You may want to do a real time amp check too. It is possible you may be pulling a little too much. Also check for a loose wire on a connection. It may be ready to pull out or hanging by a strand.
Rotax advertises 20A, but max is 18 intermittent and continuous is 16 amps.
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Fri Aug 09, 2013 1:08 pm Post subject: Rotax 912 UL alternator drop-out |
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Barry, Teflon may be a wonder product and a by product of the Manhattan Program to develop the "Bomb", but it will not carry electricity. I have a block in the shop that I tested with a VOM. It had infinite resistance and a power supply connected across it showed zero voltage coming through the block. Perhaps you were referring to the insulation used on COPPER wire? If that is the case WIRE size is WIRE size and the ability of the WIRE to allow electrons to do what they do, flow, cloud, or kill Schroedinger's cat, does not depend one whit on the insulation on the WIRE. The gage of WIRE is what determines its ability to handle amperage. Too much amperage passed though a too small wire makes what is known as a fusible link, perhaps not by design or intent, but certainly in practice. The insulation may make it possible to carry slightly more amperage without the INSULATION melting and the INSULATION type may allow for great weight savings, say Tefzel vs. PVC but again it's the COPPER WIRE that does the job and there are hundreds of thousands of aircraft and millions of automobiles that have rubber encapsulated cotton braid, PVC, Tefzel and other insulations that are flying and rolling in perfect safety. The important thing is to use the correct gage of WIRE for the circuit capacity and craft it to eliminate places that might cause the insulation to be penetrated and short the wire to ground.
Last, Teflon wire insulation has a problem and that is that it is soft. Things like nylon ties or even waxed cotton wire lacing will cause it to extrude out from under the tie and create a short. For that reason alone I would not recommend its use in an aircraft.
Rick Girard
do not archive
On Fri, Aug 9, 2013 at 7:32 AM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: | Hi Paul:
Sounds like you have a gorgeous plane.
For a standard and 99.976% of the different types of batteries to charge you MUST keep the charge voltage between 13.8 to 14.2 VDC. Over 14.2 you start to overheat the battery. Under 13.8 the voltage is not there to remove the oxides for the battery plates.
One thing you mentioned perked my ears up - Dual axis autopilot... Now, that is probably the highest single current draw in your plane. Were you in A/P? Did you hit and air bumps? When an A/P has to recover from an air pump the instantaneous current draw goes up sharply. The power is or should be drawn from the battery followed by the replenishment by the charging system. Now, from my reading Rotax has the worst charging system next to Banlon sock rubbing on a wool carpet. But, I would check things such as you mentioned - COOLING - It may be easier to install a small air scoop with a hose or fans (caution- fans have their own current draw) to blow air directly onto the ACU. This is done in quite a few planes where forced air is blown directly onto the radio stack. The other thing I would check is wire gauge size. First off it should be 'Teflon' wire and it is always better to go UP in size. IF the alternator output is rated at 18 Amps the wire size should be no smaller than a 10 AWG and I would use 8 AWG. This is one case where bigger is better. And weight for such a short run is not an issue. That takes care of the charging requirements. You will have to address the wire sizes for the other electronic equipment. Keep in mind Teflon wires allow you to use smaller gauge sizes. But, HEAT, forces you to use larger gauge sizes.
From my Rotax readings - I would say Rotax is not supplying the advertized 18 Amps and it is not in a smooth DC waveform output.
Power Reduction Sequence:
Least needed First -
Cell Phone
iPad
LIGHTS
A/P
Second Comm Radio
Second Nav/GPS
The only reasion I mention this is because an IPad under charge would be only about 1 Amp for a dead battery. A cell phone under charge - 0.1 Amp (100 mA). The other items sure can have high draw.
Another thought - How warm/hot is the firewall? IF the firewall is warm/hot or if there is dead air under the dash, you may benefit by placing the ACU on stanchions or placing it on a heat sink. A TRICK that I did on my plane: I covered the glareshield with black speaker carpet. This created a heat shield for radio stack by creating a low heat transfer barrier, aluminum and thin leatherette passes the sun's rays/heat very easily. It also added some class to the plane.
Good luck,
Barry
On Fri, Aug 9, 2013 at 12:42 AM, Paul Kuntz <paul.r.kuntz(at)gmail.com (paul.r.kuntz(at)gmail.com)> wrote:
| Quote: | I have a homebuilt Pipistrel Sinus with a Rotax 912 UL that I flew to Oshkosh and back last week. The panel has a dual Dynon Skyview display with two-axis autopilot, plus radio and transponder. The total electrical load with everything running is 7 to 8 amps. Occasionally it can go to 10 amps if I'm charging cell phone and iPad en route. I'm pretty confident that I have the electrical system wired so that the ammeter is measuring the total electrical load.
The alternator dropped out once on the outbound trip, but came back after removing the iPad charging load. The symptom was a voltage drop from 13.8 volts to 12.5 volts. On preflight the voltage may read that high for a minute or so on a freshly-charged battery, but it quickly drops to 12.2 or 12.1 volts. In flight, the voltage would drop to 12.5 volts and stay there for several minutes. I would think that if the alternator had failed, I'd see the voltage drop to the same 12.1 volts that I see on preflight, and keep dropping slowly. I can't see why it would drop to 12.5 volts and stay there, unless the voltage regulator is failing in a way that I'm not familiar with.
The alternator dropped out (same symptoms) a few times on the trip back, but by reducing the load to 3 amps (one Skyview display, radio and transponder), it stayed on line except for awhile when it seemed that the mid-day sun shining on the dashboard was adding extra heat behind the panel. That time we brought it back by directing cool air from a fresh air vent forward toward the spot where the voltage regulator is mounted inside the cabin on the back side of the firewall.
So the problem seems to be heat-related. Does this make sense? The Rotax alternator is supposed to be rated for 18 amps, and able to handle a steady load of 14 amps easily. Does the Ducati regulator have a thermal self-protect cutout? Do I perhaps have a regulator that is ready to fail completely, or should I just put an avionics cooling fan behind the panel to get the air moving?Any other ideas?
Regards,
Paul Kuntz
|
| Quote: |
ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
|
|
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Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
[quote][b]
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rv10pro(at)gmail.com
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| Posted: Fri Aug 09, 2013 5:04 pm Post subject: Rotax 912 UL alternator drop-out |
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Richard, I enjoyed reading your above post but I would also love to hear a reference to support your position on plastic zip ties and waxed cord. I am an EAA Tech Advisor and A/P with I/A for a major airline along with being ROTAX trained. Those products are used throughout the aircraft I service. I make my livelihood dealing as an Avionics Tech chasing Chafes, Shorts, Opens and errant electrons. I am always open for refreshing ideals. Flush cut wire cutters, wire spoons, a strong light source might also be on your hit list. What do you recommend?
I do support the position that zip ties should not be used on engine mounts but that subject digresses from Tefzel Mil-Spec wire and your presentation that zip ties and cordage should not be used. We use black coated cordage aft of the firewall and white coated cordage within the higher heat regimes of forward of the firewall. Chafing, routing and security of wires is an important build skill.
I look forward to the reference that drove your conclusion.
John Cox
On Fri, Aug 9, 2013 at 2:08 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
[quote]Barry, Teflon may be a wonder product and a by product of the Manhattan Program to develop the "Bomb", but it will not carry electricity. I have a block in the shop that I tested with a VOM. It had infinite resistance and a power supply connected across it showed zero voltage coming through the block. Perhaps you were referring to the insulation used on COPPER wire? If that is the case WIRE size is WIRE size and the ability of the WIRE to allow electrons to do what they do, flow, cloud, or kill Schroedinger's cat, does not depend one whit on the insulation on the WIRE. The gage of WIRE is what determines its ability to handle amperage. Too much amperage passed though a too small wire makes what is known as a fusible link, perhaps not by design or intent, but certainly in practice. The insulation may make it possible to carry slightly more amperage without the INSULATION melting and the INSULATION type may allow for great weight savings, say Tefzel vs. PVC but again it's the COPPER WIRE that does the job and there are hundreds of thousands of aircraft and millions of automobiles that have rubber encapsulated cotton braid, PVC, Tefzel and other insulations that are flying and rolling in perfect safety. The important thing is to use the correct gage of WIRE for the circuit capacity and craft it to eliminate places that might cause the insulation to be penetrated and short the wire to ground.
Last, Teflon wire insulation has a problem and that is that it is soft. Things like nylon ties or even waxed cotton wire lacing will cause it to extrude out from under the tie and create a short. For that reason alone I would not recommend its use in an aircraft.
Rick Girard
do not archive
On Fri, Aug 9, 2013 at 7:32 AM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: | Hi Paul:
Sounds like you have a gorgeous plane.
For a standard and 99.976% of the different types of batteries to charge you MUST keep the charge voltage between 13.8 to 14.2 VDC. Over 14.2 you start to overheat the battery. Under 13.8 the voltage is not there to remove the oxides for the battery plates.
One thing you mentioned perked my ears up - Dual axis autopilot... Now, that is probably the highest single current draw in your plane. Were you in A/P? Did you hit and air bumps? When an A/P has to recover from an air pump the instantaneous current draw goes up sharply. The power is or should be drawn from the battery followed by the replenishment by the charging system. Now, from my reading Rotax has the worst charging system next to Banlon sock rubbing on a wool carpet. But, I would check things such as you mentioned - COOLING - It may be easier to install a small air scoop with a hose or fans (caution- fans have their own current draw) to blow air directly onto the ACU. This is done in quite a few planes where forced air is blown directly onto the radio stack. The other thing I would check is wire gauge size. First off it should be 'Teflon' wire and it is always better to go UP in size. IF the alternator output is rated at 18 Amps the wire size should be no smaller than a 10 AWG and I would use 8 AWG. This is one case where bigger is better. And weight for such a short run is not an issue. That takes care of the charging requirements. You will have to address the wire sizes for the other electronic equipment. Keep in mind Teflon wires allow you to use smaller gauge sizes. But, HEAT, forces you to use larger gauge sizes.
From my Rotax readings - I would say Rotax is not supplying the advertized 18 Amps and it is not in a smooth DC waveform output.
Power Reduction Sequence:
Least needed First -
Cell Phone
iPad
LIGHTS
A/P
Second Comm Radio
Second Nav/GPS
The only reasion I mention this is because an IPad under charge would be only about 1 Amp for a dead battery. A cell phone under charge - 0.1 Amp (100 mA). The other items sure can have high draw.
Another thought - How warm/hot is the firewall? IF the firewall is warm/hot or if there is dead air under the dash, you may benefit by placing the ACU on stanchions or placing it on a heat sink. A TRICK that I did on my plane: I covered the glareshield with black speaker carpet. This created a heat shield for radio stack by creating a low heat transfer barrier, aluminum and thin leatherette passes the sun's rays/heat very easily. It also added some class to the plane.
Good luck,
Barry
On Fri, Aug 9, 2013 at 12:42 AM, Paul Kuntz <paul.r.kuntz(at)gmail.com (paul.r.kuntz(at)gmail.com)> wrote:
| Quote: | I have a homebuilt Pipistrel Sinus with a Rotax 912 UL that I flew to Oshkosh and back last week. The panel has a dual Dynon Skyview display with two-axis autopilot, plus radio and transponder. The total electrical load with everything running is 7 to 8 amps. Occasionally it can go to 10 amps if I'm charging cell phone and iPad en route. I'm pretty confident that I have the electrical system wired so that the ammeter is measuring the total electrical load.
The alternator dropped out once on the outbound trip, but came back after removing the iPad charging load. The symptom was a voltage drop from 13.8 volts to 12.5 volts. On preflight the voltage may read that high for a minute or so on a freshly-charged battery, but it quickly drops to 12.2 or 12.1 volts. In flight, the voltage would drop to 12.5 volts and stay there for several minutes. I would think that if the alternator had failed, I'd see the voltage drop to the same 12.1 volts that I see on preflight, and keep dropping slowly. I can't see why it would drop to 12.5 volts and stay there, unless the voltage regulator is failing in a way that I'm not familiar with.
The alternator dropped out (same symptoms) a few times on the trip back, but by reducing the load to 3 amps (one Skyview display, radio and transponder), it stayed on line except for awhile when it seemed that the mid-day sun shining on the dashboard was adding extra heat behind the panel. That time we brought it back by directing cool air from a fresh air vent forward toward the spot where the voltage regulator is mounted inside the cabin on the back side of the firewall.
So the problem seems to be heat-related. Does this make sense? The Rotax alternator is supposed to be rated for 18 amps, and able to handle a steady load of 14 amps easily. Does the Ducati regulator have a thermal self-protect cutout? Do I perhaps have a regulator that is ready to fail completely, or should I just put an avionics cooling fan behind the panel to get the air moving?Any other ideas?
Regards,
Paul Kuntz
|
|
--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
| Quote: |
ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
|
[b]
| | - The Matronics RotaxEngines-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?RotaxEngines-List |
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Sat Aug 10, 2013 6:32 am Post subject: Rotax 912 UL alternator drop-out |
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|
John, My source on the teflon wire was personal experience and the Aeroelectric connection. Based on Bob's recommendation I took a piece of teflon insulated wire and cinched it down just as I would PVC insulated wire. I did nothing to aggravate the installation, just let it set for a couple of months. At the end of that time the wire was no longer snug against the tubing and when the nylon tie was removed there was measureable decrease in insulation diameter.
Rick
On Fri, Aug 9, 2013 at 8:04 PM, John Cox <rv10pro(at)gmail.com (rv10pro(at)gmail.com)> wrote:
| Quote: | Richard, I enjoyed reading your above post but I would also love to hear a reference to support your position on plastic zip ties and waxed cord. I am an EAA Tech Advisor and A/P with I/A for a major airline along with being ROTAX trained. Those products are used throughout the aircraft I service. I make my livelihood dealing as an Avionics Tech chasing Chafes, Shorts, Opens and errant electrons. I am always open for refreshing ideals. Flush cut wire cutters, wire spoons, a strong light source might also be on your hit list. What do you recommend?
I do support the position that zip ties should not be used on engine mounts but that subject digresses from Tefzel Mil-Spec wire and your presentation that zip ties and cordage should not be used. We use black coated cordage aft of the firewall and white coated cordage within the higher heat regimes of forward of the firewall. Chafing, routing and security of wires is an important build skill.
I look forward to the reference that drove your conclusion.
John Cox
On Fri, Aug 9, 2013 at 2:08 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
| Quote: | Barry, Teflon may be a wonder product and a by product of the Manhattan Program to develop the "Bomb", but it will not carry electricity. I have a block in the shop that I tested with a VOM. It had infinite resistance and a power supply connected across it showed zero voltage coming through the block. Perhaps you were referring to the insulation used on COPPER wire? If that is the case WIRE size is WIRE size and the ability of the WIRE to allow electrons to do what they do, flow, cloud, or kill Schroedinger's cat, does not depend one whit on the insulation on the WIRE. The gage of WIRE is what determines its ability to handle amperage. Too much amperage passed though a too small wire makes what is known as a fusible link, perhaps not by design or intent, but certainly in practice. The insulation may make it possible to carry slightly more amperage without the INSULATION melting and the INSULATION type may allow for great weight savings, say Tefzel vs. PVC but again it's the COPPER WIRE that does the job and there are hundreds of thousands of aircraft and millions of automobiles that have rubber encapsulated cotton braid, PVC, Tefzel and other insulations that are flying and rolling in perfect safety. The important thing is to use the correct gage of WIRE for the circuit capacity and craft it to eliminate places that might cause the insulation to be penetrated and short the wire to ground.
Last, Teflon wire insulation has a problem and that is that it is soft. Things like nylon ties or even waxed cotton wire lacing will cause it to extrude out from under the tie and create a short. For that reason alone I would not recommend its use in an aircraft.
Rick Girard
do not archive
On Fri, Aug 9, 2013 at 7:32 AM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: | Hi Paul:
Sounds like you have a gorgeous plane.
For a standard and 99.976% of the different types of batteries to charge you MUST keep the charge voltage between 13.8 to 14.2 VDC. Over 14.2 you start to overheat the battery. Under 13.8 the voltage is not there to remove the oxides for the battery plates.
One thing you mentioned perked my ears up - Dual axis autopilot... Now, that is probably the highest single current draw in your plane. Were you in A/P? Did you hit and air bumps? When an A/P has to recover from an air pump the instantaneous current draw goes up sharply. The power is or should be drawn from the battery followed by the replenishment by the charging system. Now, from my reading Rotax has the worst charging system next to Banlon sock rubbing on a wool carpet. But, I would check things such as you mentioned - COOLING - It may be easier to install a small air scoop with a hose or fans (caution- fans have their own current draw) to blow air directly onto the ACU. This is done in quite a few planes where forced air is blown directly onto the radio stack. The other thing I would check is wire gauge size. First off it should be 'Teflon' wire and it is always better to go UP in size. IF the alternator output is rated at 18 Amps the wire size should be no smaller than a 10 AWG and I would use 8 AWG. This is one case where bigger is better. And weight for such a short run is not an issue. That takes care of the charging requirements. You will have to address the wire sizes for the other electronic equipment. Keep in mind Teflon wires allow you to use smaller gauge sizes. But, HEAT, forces you to use larger gauge sizes.
From my Rotax readings - I would say Rotax is not supplying the advertized 18 Amps and it is not in a smooth DC waveform output.
Power Reduction Sequence:
Least needed First -
Cell Phone
iPad
LIGHTS
A/P
Second Comm Radio
Second Nav/GPS
The only reasion I mention this is because an IPad under charge would be only about 1 Amp for a dead battery. A cell phone under charge - 0.1 Amp (100 mA). The other items sure can have high draw.
Another thought - How warm/hot is the firewall? IF the firewall is warm/hot or if there is dead air under the dash, you may benefit by placing the ACU on stanchions or placing it on a heat sink. A TRICK that I did on my plane: I covered the glareshield with black speaker carpet. This created a heat shield for radio stack by creating a low heat transfer barrier, aluminum and thin leatherette passes the sun's rays/heat very easily. It also added some class to the plane.
Good luck,
Barry
On Fri, Aug 9, 2013 at 12:42 AM, Paul Kuntz <paul.r.kuntz(at)gmail.com (paul.r.kuntz(at)gmail.com)> wrote:
| Quote: | I have a homebuilt Pipistrel Sinus with a Rotax 912 UL that I flew to Oshkosh and back last week. The panel has a dual Dynon Skyview display with two-axis autopilot, plus radio and transponder. The total electrical load with everything running is 7 to 8 amps. Occasionally it can go to 10 amps if I'm charging cell phone and iPad en route. I'm pretty confident that I have the electrical system wired so that the ammeter is measuring the total electrical load.
The alternator dropped out once on the outbound trip, but came back after removing the iPad charging load. The symptom was a voltage drop from 13.8 volts to 12.5 volts. On preflight the voltage may read that high for a minute or so on a freshly-charged battery, but it quickly drops to 12.2 or 12.1 volts. In flight, the voltage would drop to 12.5 volts and stay there for several minutes. I would think that if the alternator had failed, I'd see the voltage drop to the same 12.1 volts that I see on preflight, and keep dropping slowly. I can't see why it would drop to 12.5 volts and stay there, unless the voltage regulator is failing in a way that I'm not familiar with.
The alternator dropped out (same symptoms) a few times on the trip back, but by reducing the load to 3 amps (one Skyview display, radio and transponder), it stayed on line except for awhile when it seemed that the mid-day sun shining on the dashboard was adding extra heat behind the panel. That time we brought it back by directing cool air from a fresh air vent forward toward the spot where the voltage regulator is mounted inside the cabin on the back side of the firewall.
So the problem seems to be heat-related. Does this make sense? The Rotax alternator is supposed to be rated for 18 amps, and able to handle a steady load of 14 amps easily. Does the Ducati regulator have a thermal self-protect cutout? Do I perhaps have a regulator that is ready to fail completely, or should I just put an avionics cooling fan behind the panel to get the air moving?Any other ideas?
Regards,
Paul Kuntz
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Zulu Delta
Mk IIIC
Thanks, Homer GBYM
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Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
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BARRY CHECK 6
Joined: 15 Mar 2011
Posts: 738
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| Posted: Sun Aug 11, 2013 6:56 pm Post subject: Rotax 912 UL alternator drop-out |
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Rich:
You almost had me with your first statements. But, after reading the rest of your email I realized you are misinformed That's OK, many a person confuse things such as you did.
Lets cover some basics of wire and insulation and safety.
1 - What determines the amperage carrying capabilities of a wire?
Your answer was the wire size. NOT completely true. LQQk up wire size and note that the amperage rating is DIFFERENT for the same wire with DIFFERENT insulation. WHY?
Think of it this way: What is the FIRST thing to FAIL in a excessive current situation? It is NOT the wire... It is the INSULATION. Ergo, Insulation is the controlling factor.
Remember this and you will stump 99.67% of the electrical engineers out there.
2 - Wire - As in the copper wire you are thinking about is rated in Square Mills. But, it is easier to convert it to a easy number to deal with know as AWG (American Wire Gauge) or BWG (British Wire Gauge). But, remember it is the Square Mills and not even the copper.
3 - YES - Ty-wraps and Lacing Cord can cut into ALL insulations and that is why a sheth is recommended in some situations (See AC43-13) but the REAL culprit is the INSTALLER. The inexperienced installer does not have the proper tool to install the Ty-wrap. The Proper tool is required to make sure the proper tension is applied to the Ty-wrap and the tool has to be calibrated. MANY an installer does not make the Ty-wrap tight enough and that leads to vibration - Vibration leads to the slow cutting into the insulation.
Along with vibration is improper spacing of the Ty-wraps.
Now, some may think that OVER tightening would be the cause but that is not the situation as proven by ASTM testing.
Next is the Lacing Cord - Well, for years Mill Specs has tried to establish a testing method to identify good lacing, but all have FAILED! There is no way to verify how well a bundle is laced - - - How tight, how loose. So the best they were able to do is to LQQK at it. Someone came up with the idea of using a tapered pin to slide between the wires and the lacing... NOPE! That did not work either. LQQK at it and the years of practical experience will tell the experienced eye what is good or not. Yet! The spacing of the lacing and the type of knot is covered in AC43-13.
4 - HUGE - Fupa Rich. You NEVER want to use PVC wire for a plane. Wait for it... Wait for it... You will argue that your plane is experimental and you can do whatever you want.
Well, that is why you have a placard in your plane that states: This aircraft is amature built and does not comply with current FAA standards of standard aircraft.
PVC melts at a lower temperature than Teflon/Tefzel - AND - it is NOT self-extinguishing - AND - It puts out hazardous fumes.
That is why it is not recommended for aviation. Again AC43-13.
5 - SO why use Teflon/Tefzel?
Because of engineering/design reasons (as you mentioned) - Thinner and Lighter wires can be use, which allows smaller access points and less weight and the pull strength of the wire increases also. And MORE amperage... Not "slightly more" - Significantly more.
Look up the charts - In some cases the amperage DOUBLES with Teflon/Tefzel insulation.
6 - Lastly - "Last, Teflon wire insulation has a problem and that is that it is soft." Sorry Rich - You have things confused... It is NOT soft and that is the problem. It is hard, requires a larger bend radius and when exposed to years of service or in the sun the very outer coating dries up and cracks which becomes abrasive. The outer coating is used for marking the wire as very few things stick to Teflon/Tefzel. Running Teflon/Tefzel wire requires proper securing of the wire bundles. This is because even if the very outer coating is not dried and cracked it is still very abrasive against itself.
7 - Oh, I've been using the terms Teflon/Tefzel as interchangeable. Not really - Teflon has been removed and replaced by Tefzel. There were some chemistry issues that I do not recall. Yet, for most of us - When the term Teflon wire comes up everyone knows it is Tefzel. Sort of like Tissues and Kleanx.
BTW - You don't use a VOM to test for insulation. You use a MEGGER.
Rich said: "For that reason alone I would not recommend its use in an aircraft." And Rich, I would recommend that you read AC43-13 - Again.
Barry
On Fri, Aug 9, 2013 at 5:08 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
[quote]Barry, Teflon may be a wonder product and a by product of the Manhattan Program to develop the "Bomb", but it will not carry electricity. I have a block in the shop that I tested with a VOM. It had infinite resistance and a power supply connected across it showed zero voltage coming through the block. Perhaps you were referring to the insulation used on COPPER wire? If that is the case WIRE size is WIRE size and the ability of the WIRE to allow electrons to do what they do, flow, cloud, or kill Schroedinger's cat, does not depend one whit on the insulation on the WIRE. The gage of WIRE is what determines its ability to handle amperage. Too much amperage passed though a too small wire makes what is known as a fusible link, perhaps not by design or intent, but certainly in practice. The insulation may make it possible to carry slightly more amperage without the INSULATION melting and the INSULATION type may allow for great weight savings, say Tefzel vs. PVC but again it's the COPPER WIRE that does the job and there are hundreds of thousands of aircraft and millions of automobiles that have rubber encapsulated cotton braid, PVC, Tefzel and other insulations that are flying and rolling in perfect safety. The important thing is to use the correct gage of WIRE for the circuit capacity and craft it to eliminate places that might cause the insulation to be penetrated and short the wire to ground.
Last, Teflon wire insulation has a problem and that is that it is soft. Things like nylon ties or even waxed cotton wire lacing will cause it to extrude out from under the tie and create a short. For that reason alone I would not recommend its use in an aircraft.
Rick Girard
do not archive
On Fri, Aug 9, 2013 at 7:32 AM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: | Hi Paul:
Sounds like you have a gorgeous plane.
For a standard and 99.976% of the different types of batteries to charge you MUST keep the charge voltage between 13.8 to 14.2 VDC. Over 14.2 you start to overheat the battery. Under 13.8 the voltage is not there to remove the oxides for the battery plates.
One thing you mentioned perked my ears up - Dual axis autopilot... Now, that is probably the highest single current draw in your plane. Were you in A/P? Did you hit and air bumps? When an A/P has to recover from an air pump the instantaneous current draw goes up sharply. The power is or should be drawn from the battery followed by the replenishment by the charging system. Now, from my reading Rotax has the worst charging system next to Banlon sock rubbing on a wool carpet. But, I would check things such as you mentioned - COOLING - It may be easier to install a small air scoop with a hose or fans (caution- fans have their own current draw) to blow air directly onto the ACU. This is done in quite a few planes where forced air is blown directly onto the radio stack. The other thing I would check is wire gauge size. First off it should be 'Teflon' wire and it is always better to go UP in size. IF the alternator output is rated at 18 Amps the wire size should be no smaller than a 10 AWG and I would use 8 AWG. This is one case where bigger is better. And weight for such a short run is not an issue. That takes care of the charging requirements. You will have to address the wire sizes for the other electronic equipment. Keep in mind Teflon wires allow you to use smaller gauge sizes. But, HEAT, forces you to use larger gauge sizes.
From my Rotax readings - I would say Rotax is not supplying the advertized 18 Amps and it is not in a smooth DC waveform output.
Power Reduction Sequence:
Least needed First -
Cell Phone
iPad
LIGHTS
A/P
Second Comm Radio
Second Nav/GPS
The only reasion I mention this is because an IPad under charge would be only about 1 Amp for a dead battery. A cell phone under charge - 0.1 Amp (100 mA). The other items sure can have high draw.
Another thought - How warm/hot is the firewall? IF the firewall is warm/hot or if there is dead air under the dash, you may benefit by placing the ACU on stanchions or placing it on a heat sink. A TRICK that I did on my plane: I covered the glareshield with black speaker carpet. This created a heat shield for radio stack by creating a low heat transfer barrier, aluminum and thin leatherette passes the sun's rays/heat very easily. It also added some class to the plane.
Good luck,
Barry
On Fri, Aug 9, 2013 at 12:42 AM, Paul Kuntz <paul.r.kuntz(at)gmail.com (paul.r.kuntz(at)gmail.com)> wrote:
| Quote: | I have a homebuilt Pipistrel Sinus with a Rotax 912 UL that I flew to Oshkosh and back last week. The panel has a dual Dynon Skyview display with two-axis autopilot, plus radio and transponder. The total electrical load with everything running is 7 to 8 amps. Occasionally it can go to 10 amps if I'm charging cell phone and iPad en route. I'm pretty confident that I have the electrical system wired so that the ammeter is measuring the total electrical load.
The alternator dropped out once on the outbound trip, but came back after removing the iPad charging load. The symptom was a voltage drop from 13.8 volts to 12.5 volts. On preflight the voltage may read that high for a minute or so on a freshly-charged battery, but it quickly drops to 12.2 or 12.1 volts. In flight, the voltage would drop to 12.5 volts and stay there for several minutes. I would think that if the alternator had failed, I'd see the voltage drop to the same 12.1 volts that I see on preflight, and keep dropping slowly. I can't see why it would drop to 12.5 volts and stay there, unless the voltage regulator is failing in a way that I'm not familiar with.
The alternator dropped out (same symptoms) a few times on the trip back, but by reducing the load to 3 amps (one Skyview display, radio and transponder), it stayed on line except for awhile when it seemed that the mid-day sun shining on the dashboard was adding extra heat behind the panel. That time we brought it back by directing cool air from a fresh air vent forward toward the spot where the voltage regulator is mounted inside the cabin on the back side of the firewall.
So the problem seems to be heat-related. Does this make sense? The Rotax alternator is supposed to be rated for 18 amps, and able to handle a steady load of 14 amps easily. Does the Ducati regulator have a thermal self-protect cutout? Do I perhaps have a regulator that is ready to fail completely, or should I just put an avionics cooling fan behind the panel to get the air moving?Any other ideas?
Regards,
Paul Kuntz
|
|
--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
| Quote: |
ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
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BARRY CHECK 6
Joined: 15 Mar 2011
Posts: 738
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| Posted: Mon Aug 12, 2013 11:51 pm Post subject: Rotax 912 UL alternator drop-out |
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Right you are Roger:
And when it comes to "INSPECTION" of electrical connections - Especially Grounds - LQQKing at them is NOT inspecting. You must Remove them, Clean them and Replace the Star Washer. And then if you are really good, Coat them with Dielectric Grease or Paint... This keep moisture from starting the corrosion process all over again.
You cannot see the corrosion all the time but, you sure can see the effects.
Barry
On Fri, Aug 9, 2013 at 10:07 AM, Roger Lee <ssadiver1(at)yahoo.com (ssadiver1(at)yahoo.com)> wrote:
[quote]--> RotaxEngines-List message posted by: "Roger Lee" <ssadiver1(at)yahoo.com (ssadiver1(at)yahoo.com)>
Your system can handle 16 amp continuous load. With this jumping around like this my first pick for the problem is a poor ground. Most of the time on the LSA I work on I find loose grounds. They may be hand tight, but wrench loose. Put a wrench on all your grounds. I have found that this solves 80% of the electrical issues on LSA especially where composite aircraft are concerned. Depending on where you live corrosion can be a factor too. You may want to do a real time amp check too. It is possible you may be pulling a little too much. Also check for a loose wire on a connection. It may be ready to pull out or hanging by a strand.
Rotax advertises 20A, but max is 18 intermittent and continuous is 16 amps.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center - Heavy Maint. Rated
Home [url=tel:520-574-1080]520-574-1080[/url] TRY HOME FIRST
Cell [url=tel:520-349-7056]520-349-7056[/url]
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