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Why do some of the RV-12 VRs die young?

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?
 
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.
 
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.
 
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.aviation/photos/?tab=album&album_id=1536023419862973&ref=page_internal

I posted the mod here at VAF too. http://www.vansairforce.com/community/showpost.php?p=1339414&postcount=306
 
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.
 
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
 
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.
 
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.
 
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.

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.
 
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
 
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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
 
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.
 
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.
 
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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.
 
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.
 
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.
 
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.
 
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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