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-   -   Why do some of the RV-12 VRs die young? (https://vansairforce.net/community/showthread.php?t=145841)

Mich48041 02-10-2017 08:29 AM

The Ducati mounting holes for 1/4" bolts are about 3 5/8" apart center to center.

jweir43 02-10-2017 05:44 PM

Thanks, Mike. For whatever reason those google docs gave me a "file not found" error. I'll see if my Chrome browser will bring them up.

As I understand it, this little sucker takes in an AC wave and outputs a nominal 12 volts at 20 amps or so. Did I get that right?

Now, where in the aircraft do those 20 amps get used? And is there any regulation at all on the incoming AC, or is it just a linear function of engine speed. Any idea what the minimum/maximum frequency of the AC is?

That'll get me started to think.

Jim

DaleB 02-10-2017 07:28 PM

Quote:

Originally Posted by jweir43 (Post 1149169)
Thanks, Mike. For whatever reason those google docs gave me a "file not found" error. I'll see if my Chrome browser will bring them up.

As I understand it, this little sucker takes in an AC wave and outputs a nominal 12 volts at 20 amps or so. Did I get that right?

Now, where in the aircraft do those 20 amps get used? And is there any regulation at all on the incoming AC, or is it just a linear function of engine speed. Any idea what the minimum/maximum frequency of the AC is?

That'll get me started to think.

Jim

Can't answer the frequency question, and I don't know the voltage but have read that it's 15 - 20 VAC at idle and 30 - 40 at cruise RPM. I don't know how accurate that is, but the frequency will certainly depend on engine RPM.

Power is used for the fuel pump, EFIS, COM radio, transponder, intercom, autopilot, Garmin 496 in older airplanes, strobe/nav/landing lights in some. EFIS setups can be single or dual Dynon D180, single or dual G3X Tough, single or dual Dynon Skyview, Skyview Touch or HDX. COM radios are SL40 or GTR 200. Oh, there's also a 12V power outlet. I may have missed one or two minor items.

deene 02-10-2017 08:32 PM

Hi Jim, welcome aboard.

Some additional Rotax regulator/rectifier info:

Normal regulator/rectifier performance:
Output voltage range: 13.9-14.5 VDC
Max current: 22 A (other sources show 18-20A)
Max temperature: 80 deg C (176 deg F)

Here is a link to a nice test program document on the Rotax electrical system by a competent EE:

http://www.scflier.com/index.php?/to...trical-system/

Mich48041 02-10-2017 09:57 PM

The 22,000 microfarad capacitor does not do a very good job of stabilizing the voltage. Last year, I conducted an experiment by disconnecting the battery while the engine was running. The voltage fluctuated between 13.25 and 14.7

pilotyoung 03-16-2019 10:41 PM

Ducati Voltage Regulator
 
In the last three weeks I have had two very experienced Rotax mechanics tell me the problem with the Ducati is that the RV-12 does not have a dedicated ground wire. Those mechanics told me when the Ducati is used in other small aircraft, where they run a dedicated ground wire, the problems don't exist. It relies on getting ground through the chassis. When my Ducati failed, I replaced it with a John Deere from Amazon and I installed a dedicated ground wire to the case. It worked fine for about 40 hours and I just replaced it with the Silent Hektik. The John Deere didn't fail. I just decided I wanted overvoltage protection and the Silent Hektik incorporates this feature. Also, the Silent Hektik has a terminal for a dedicated ground. I just installed the Silent Hektik today while I am doing the annual condition inspection. I should be finished by Wednesday and will see how it works. It does have a terminal for an alarm light and I hooked it up to my Dynon Skview HDX. My installation copies another gentlemen from Vans Airforce and I am taking cooling air for the blast tube from the fiberglass duck on the pilotside that supplies air to the radiator. I think it is a neat installation and should work well. I also put a thermo strip on the Voltage Regulator so I can determine the temperatures it is exposed to. Lastly, I must confess none of these ides are original with me. I got them all off of Vans Airforce and I think you creative people for posting your ideas.

Phantom30 03-17-2019 12:36 PM

Quote:

Originally Posted by Mich48041 (Post 1149229)
The 22,000 microfarad capacitor does not do a very good job of stabilizing the voltage. Last year, I conducted an experiment by disconnecting the battery while the engine was running. The voltage fluctuated between 13.25 and 14.7

Joe....I am a novice when it comes to electronics. When my VR took a dump, I switched to the SH VR (and after reading an German artical; added a 32,000 microfarad capacitor..which they recommended).

Everything has been rock solid since then....the bloody capacitor is ?big?.. Your thoughts?

rvbuilder2002 03-17-2019 01:45 PM

Quote:

Originally Posted by Phantom30 (Post 1332197)
Joe....I am a novice when it comes to electronics. When my VR took a dump, I switched to the SH VR (and after reading an German artical; added a 32,000 microfarad capacitor..which they recommended).

Everything has been rock solid since then....the bloody capacitor is ?big?.. Your thoughts?

I'm not Joe, but I can tell you that when Van's began working with S H for an installation on the RV-12 their engineers said the existing 22000 mf cap was fine.

h&jeuropa 03-17-2019 03:10 PM

Mike Miller put together a nice replacement for the Ducatti. Here is the thread
http://www.vansairforce.com/communit...or#post1296750

Post 45 has the details. I have constructed mine and installed it, but until the weather clears I won't have a chance to test it in flight. The cost was about $75.

Jim Butcher

Mich48041 03-17-2019 03:26 PM

I have not observed any benefit to adding a large capacitor to the output of an alternator.
The ability of 22,000 mfd capacitors to store and release electrons is very
small compared to the output of an alternator. A battery does a much better job.
_ A good experiment would be to disconnect that big 32,000 microfarad
capacitor to see if it makes any noticeable difference.

Rrhsch 09-24-2019 03:03 PM

I have added a B and C spline alternator on the Rotax as a back up and to supply the power for heated pitot, MFD and VOR/ILS.

I am installing the Silent-Hektik from Vans And I would like to add a switch to turn the alternator off in case of a failure. I have searched this forum and I am unclear as to what wire I should be using to switch off the alternator when using the Silent-Hektik VR.

The Z16 drawing shows the C wire connected to the alt on off switch. Would this be the same for the Silent-Hektik?

Strappe 10-23-2019 11:55 AM

I'm about to install the Vans Aircraft Silent Hektik voltage regulator kit in our 2015 RV-12. We just had our first VR failure last week at 200 hrs. The current Ducati regulator is mounted in the cockpit under the avionics shelf.

Question: Has anyone mounted the SH in the same position under the avionics shelf and measured the temperatures of the SH VR?

That's what I would like to try first. I know this is not the Van's-approved installation position. The salesman told me that when I phoned in my order, but he couldn't give me evidence of failure other than to say VRs need a lot of cooling and the only approved method is to move the mounting for the new SH VR to the engine compartment location, cut a hole in the top of my nice cowling, and install the NACA scoop.

I've spent many hours searching and found many inventive ideas for cooling the Ducati and JD VRs, and a few (like Torsen in his blog) using the SH VR, but proof of success or failure is more or less anecdotal: it either failed again or it hasn't failed yet. Note that Torsen did measure temps when he put his SH VR in the radiator cooling housing, and the final note of his blog (where did he go?) was that the temps were surprisingly higher than he had hoped.

pilotyoung 10-23-2019 10:35 PM

Why do some of the RV-12 VR's die young?
 
I bought a SH from a motorcycle shop in England. My airplane had the VR in the original location. I copied some other people on here and just moved it a little more left, to get it out of the air stream of the radiator. I then put in a scat tube that draws air out of the air channel on the left side of the engine compartment (where the radiator is mounted). I put a thermal strip on it and 135C is the highest temperature on the VR. There are some pictures of my installation on page 31 of what changes have you made to your RV-12 on this web site.

Again, my idea was not original. I got it from some creative guy on this web site. But it is working fine and has been installed for about 6 months and over 50 hours.

magiccarpet 10-23-2019 11:27 PM

Quote:

Originally Posted by Strappe (Post 1381550)
Question: Has anyone mounted the SH in the same position under the avionics shelf

That's exactly what I did. I replaced the Ducati VR at only 8h for preventive reasons by the SH. Now I still only have 30h so I can't speak about long term reliability but the VR works just great.
You may see images here https://m.facebook.com/magic.carpet....=page_internal

I posted the mod here at VAF too. http://www.vansairforce.com/communit...&postcount=306

ben barron 10-24-2019 08:59 AM

I thought about installing the SH in the cockpit but SH says in their installation instructions and printed on the VR to not install in the cockpit. I bit the bullet and installed it per Vans instructions.

benfra 10-24-2019 09:35 AM

VR Regulator
 
Installed as Vans Instructions, was able to install scoop before AC was painted, otherwise simple install. Works great so far with 48 hours. GL Ben

lon@carolon.net 10-24-2019 09:43 AM

Could a dead (or dying) voltage regulator cause fatal damage to a stator?

I ask, because my battery is no longer charging. My Ducati VR showed signs of failure (bulges on the black underside) so I replaced it with a new one, but the battery still isn?t charging. Next step will be to test the stator. If that needs replacing too, I?m wondering whether the VR and stator failures are linked, or just coincidental.

NinerBikes 10-24-2019 09:58 AM

In the automotive world, electrical failures are usually linked. Diodes fail, or voltage regulator fails, puts excessive load on generator or alternator, eats up the brushes, bulges and overcharges the battery, and sooner or later you see blue smoke for the whole charging system.

I would suspect it's the same on a Rotax motor and RV-12 electrical system.

Tony_T 10-24-2019 10:17 AM

Quote:

Originally Posted by NinerBikes (Post 1381750)
In the automotive world, electrical failures are usually linked. Diodes fail, or voltage regulator fails, puts excessive load on generator or alternator, eats up the brushes, bulges and overcharges the battery, and sooner or later you see blue smoke for the whole charging system.

I would suspect it's the same on a Rotax motor and RV-12 electrical system.

Randy, this is hyperbole and not helpful.

Quote:

Originally Posted by lon@carolon.net (Post 1381748)
Could a dead (or dying) voltage regulator cause fatal damage to a stator?

I ask, because my battery is no longer charging. My Ducati VR showed signs of failure (bulges on the black underside) so I replaced it with a new one, but the battery still isn?t charging. Next step will be to test the stator. If that needs replacing too, I?m wondering whether the VR and stator failures are linked, or just coincidental.

Lon, someone on the forum will chime in with useful troubleshooting advice.

alexe 10-24-2019 12:27 PM

Disconnect the stator wires from the regulator. The resistance between the two yellow wires coming from the stator should be between .1 and .8 ohms (from Rotax mtc manual).
Alex

E. D. Eliot 10-24-2019 02:35 PM

PM Sent
 
Hi, Rick - I sent you a PM. I think that the B&C add on is an excellent solution. Hoping that you can give us more info. Thanks, Ed Eliot

Mich48041 10-24-2019 05:49 PM

The Rotax alternator has no moving parts (unless you count the engine flywheel). The alternator consists of some stationary coils of wire connected in series. The coils seldom fail. If there is continuity between the two heavy yellow wires coming from the alternator, and they are not shorted to ground then the alternator is likely good. Read THIS THREAD to see how Bill H checked the stator voltage with engine running.

NinerBikes 10-25-2019 11:47 AM

We think N836BL with 187 hrs just got added to the list of Ducati Voltage Regulator slash Charge controller failures.

Voltage is just acting horrendous... 4000 rpm run up, 13.3 V - 8 amps, then 2000 rpm, 13.7V -2 amps. Problem clears up, acts intermittent, then /sky view shows 14.2 V and a 9 or 10 amp recharging rate at 5100 rpm in cruise. Later comes down as battery gets charged back up, to 13.7 or 13.8 V and 1 to 2 amp charge rate. Again, once on the ground -9 amps at 2000 to 2500 rpms.

Intermittent positive amp charge rates and dumps the 13.7V to 14.1 to 14.2V with positive amps, regardless of engine RPMs. Pretty much before this, 2500 rpms always showed a positive 1 to 5 or 6 amp charge rate, depending upon if the motor was just started up.

Ordered the John Deere model, has the most amount of surface fin for heat dissipation and is black anodized. You can search Ebay or Amazon for Rectifier Voltage Regulator John Deere Mowers Tractors AM101406 MIA881279

The Skyview D1000 Touch is rated up to 30.0V, I believe the Garmin GTR-200 is also. Can't speak for the rest of the lights on the plane or the Rotax ignition system.

rvbuilder2002 10-25-2019 12:22 PM

The Rotax 912ULS alternator has a very limited output capability (about 18 amps max.)

Idle RPMs shortly after an engine start, particularly if a lot of cranking happened or the battery was bit low, will often indicate voltages of well below nominal (14.2 or so)

Even at higher power settings such as during run up, lower voltages are common if the battery was run down during start, and all of the aircraft systems are powered on.

If after flying for a while, the voltage seems to recover to normal, the regulator is probably fine.

NinerBikes 10-25-2019 06:35 PM

Quote:

Originally Posted by rvbuilder2002 (Post 1381959)
The Rotax 912ULS alternator has a very limited output capability (about 18 amps max.)

Idle RPMs shortly after an engine start, particularly if a lot of cranking happened or the battery was bit low, will often indicate voltages of well below nominal (14.2 or so)

Even at higher power settings such as during run up, lower voltages are common if the battery was run down during start, and all of the aircraft systems are powered on.

If after flying for a while, the voltage seems to recover to normal, the regulator is probably fine.

Not a problem, will keep an eye on it, and keep regulator in the plane, that way, we always have a plug and play spare.

NinerBikes 01-28-2020 02:13 PM

After 2 past flights where Voltage Regulator acts normal on run up, but stops charging right upon rotation and take off, showing 12.3 V and -9 to -10 amps, including no charging for the first 12 minutes before all of a sudden the Ducati VR made it's mind up it was going to work and charge up the battery, we decided enough was enough.

R&R'd the spare Voltage Regulator with 216.5 hrs on the Hobbs meter.

Noticed immediate improvement, now +1 to +2 amps showing at 2150 rpms on start up, and 13.7 V. We used to have to see 2700 rpm before positive amps rate of charge would just barely show up at 0 to +1 amp.

Replacement was a Chinese Ducati version of the Voltage regulator, about $36 plus sales tax at 9.5% here in Los Angeles., if i recall correctly.

We would usually see state of charge of battery at completion of a flight of 13.13 to 13.15V. Todays short flight showed 13.25V in 2/10 of an hour take off, and landing.

Hoping this problem is behind us for a while now.

designrs 01-29-2020 09:52 PM

Corrosion! You want all of the connectors cleaned and covered with dielectric grease.

More here on this Rotax specific part, along with how to reduce early failures from heat:

http://www.scflier.com/topic/1249-ne...&comment=14205

pilotyoung 02-11-2020 12:23 AM

Why do some of the RV-12 VRs die young
 
One very experience Rotax mechanic opined to me that the reason for the early failure of the VRs in the RV-12 is that Van's does not supply a dedicated ground wire from the battery to the VR. He said that in our airplanes with Rotax engines, there is a dedicated ground wire from the battery to the VR and the VRs do not fail early. He says that since Van's uses the chassis for a ground, and the conductivity is not as good as a dedicated ground wire. He suggests adding a dedicated ground wire from the battery to the VR.

This is one man's opinion but he has worked on Rotax engines for a number of years on several different airframes. When I installed the SK, it has a terminal for a dedicated ground wire from the battery.

So draw your own conclusion. If I had an RV-12 with the Ducatti VR, I would add a dedicated ground wire to the battery. It will not cost much and it certainly can't hurt anything.

tomkk 02-11-2020 05:48 AM

Quote:

Originally Posted by pilotyoung (Post 1407028)
One very experience Rotax mechanic opined to me that the reason for the early failure of the VRs in the RV-12 is that Van's does not supply a dedicated ground wire from the battery to the VR.

Tried that - didn't work. Finally gave up and switched to the S-H VR. So far, so good ...


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