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

E. D. Eliot

Well Known Member
I know that this has been hashed out a lot - but - I can't help but wonder what it about the RV-12 electrical system that is causing some VRs to die quite young? It it inadequate generation source for the electronics and lights that we are running? Is it the VRs themselves - are they undersized? Under built? Poorly built? Should we try, for instance, Ford, GMC, Chrysler VRs? Why only Bugatti and tractor VRs? Seems that those who are flying other types of aircraft with the Rotax 912 don't have this problem. Maybe I'm wrong?

From where I sit with no personal experience and only the VAF as my source of info, it appears that`something must be wrong with the RV-12 'system'. With ?????K Rotax engines flying, why do we have this recurring problem? Carry an extra RV whenever I leave my home airport? Really? Something is wrong - what is it?
 
Ed - -

My best guess is the load being placed on them. I have a lighter load on mine, and over 1,000 hours, and no problem. If you run lights, a second screen, headlights, etc., that heats up the VR. Having the VR in a warm airstream does not help likely. In the air duct to the radiator would be best in my opinion.
 
I don't believe a different automotive regulator would be an option. Normal automotive systems regulate the output voltage by controlling the field winding current to the alternator. The Rotax alternator uses permanent magnets, not field coils, so they work completely differently. The regulator is actually a rectifier and regulator.
 
I agree with John on this. I think its the increase loads put on them with addition of cockpit goodies and lights. I have 760 hours on mine mounted in the original location . I have no lights or extras running. It has had no issues since new in 2009.

Brad Stiefvater
Salem SD
 
I agree with John on this. I think its the increase loads put on them with addition of cockpit goodies and lights. I have 760 hours on mine mounted in the original location . I have no lights or extras running. It has had no issues since new in 2009.

Brad Stiefvater
Salem SD

My 12 has no lights or AP. Ducati bought the farm at just over 100 hrs. John Deere VR mounted in same location now has over 100 hrs. I made a heavy aluminum sub-plate and used thermal paste for better heat dissipation.
 
The Ducati part is a marginal design. There have been failures for a long time on these parts where the electrical system is operating near peak current capacity. Rotax does offer an external alternator where more current capacity is required.
 
The Ducati part is a marginal design. There have been failures for a long time on these parts where the electrical system is operating near peak current capacity. Rotax does offer an external alternator where more current capacity is required.

I would tend to agree with the above statement regarding the Ducati regulator. IMHO the heat sink fins are marginal at best for the power the unit needs to dissipate for the RV-12, especially one that is loaded with options.

The Silent Hektik unit I picked up is rated for more than double the current loads our RV-12's draw fully loaded. The unit has probably three times as much heat sink fin area compared to the Ducati unit and also has a flat machined aluminum base to aid in transferring heat away from the regulator and into the mounting surface (especially when a good heat sink compound is applied).

Currently the plan is to install my Silent Hektik on the firewall shelf or upper firewall underneath the brake reservoir so the regulator will not have hot air blowing directly onto it from the radiator. Also plan to tap into the air duct in the lower cowl forward of the radiator and run a scat tube to the unit so cool air can blow directly onto the rectifier/regulator.
 
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Correct me if I am wrong, but I believe the Silent Hektik is not available in the US. Tried to find a source a while back but to no avail. Anyone know where to get the Silent Hektit in the US??? On my third regulator. 1st lasted 170 hrs. 2nd lasted about 350.
 
Correct me if I am wrong, but I believe the Silent Hektik is not available in the US. Tried to find a source a while back but to no avail. Anyone know where to get the Silent Hektit in the US??? On my third regulator. 1st lasted 170 hrs. 2nd lasted about 350.

You are correct about the Silent Hektik not being available in the States .... however, that does not mean it can't be obtained. I ordered mine from a motorcycle shop in England that sells Silent Hektik products. It was ordered through his supplier in Germany and then shipped to me from England. I made no mention of it going on an aircraft, nor was I asked ... just said I was looking for a R4112 Silent Hektik regulator to be shipped to me in the States ... it was not a problem.

There was a small issue with the leads though, apparently the regulators are not available any longer with spade leads on the regulator ... now the regulator comes with wires coming out of the regulator with bullet connectors attached to the wires, not a big deal I'll just cut off the bullet ends and replace them with spade terminals for compatibility with the ends on the Rotax engine's wires.

Return from the future: Fortunately before wiring up the Silent Hektik F-4112 regulator I have with wires comming out of the unit, I noticed a small difference in a couple of the drawings at the Silent Hektik site. Fortunately, I had the presence of mind to filter the Silent Hektik WEB pages through a German to English translator. I was surprised to receive a version of the F-4112 regulator with wires coming out of the regulator ... even though the unit was the same part number as a unit that a photo was posted of here in the VAF forums with the exact same part number but with spade terminals. Apparently, there were variants of the F-4112 regulator at the time the order was placed. To my understanding, all the units with wires coming out of the regulator are wired differently ?. and NOT what we want as a replacement for the Ducati regulator.

Builders beware!!! Here is the BIG BIG difference. On the standard Ducati regulator reading the terminals from left to right you have G G R +B L C. On the Silent Hektik F-4112 WITH WIRES, the terminals are marked as G G R ?B L C. Yet the Silent Hektik unit that has the same F-4112 part number but with the spade connectors like the Ducati unit the terminals are marked as G G R +B L C.

The big difference is where the regulator receives it ground from ?. The F-4112 unit WITH WIRES gets it ground from the ?B lead (blue) which needs to be connected to the battery's ground terminal ? however, the RV-12 wiring configuration connects this lead to the battery's positive terminal, not good!!! Yet, the regulator version with the spade leads uses the regulator case as the ground and the +B terminal is connected to the battery's positive terminal, as it is in our RV-12 application.

I?m assuming this must have created quite a bit of confusion which is likely why Silent Hektik changed the part number to F-4118 for the regulator with the spade terminals and now the one they recommend on their WEB site as the replacement for the Ducati regulator on Rotax912/914 engines. ? the F-4118 regulator IS the one we want to install as the direct plugin replacement for the Ducati regulator. The leads are marked as G G R +B L C which is what we want. The F-4118 regulator also has an added feature of a four stepped voltage output ... so it can be used not only on lead acid batteries, but also on ion batteries as well. If you have one of the F-4112 regulators with the spade leads you should be OK just check that the sticker above the terminals says +B and NOT -B. Just be sure NOT to use one of the regulators with the wires because it is NOT pin for pin compatible with the Ducati regulator.
 
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As far as I can make out this is not an RV12 related issue rather a Rotax 912 problem, they do not seem to last long in any installation, carrying a spare is common here.
 
What did the R4112 Silent Hektik regulator cost and what makes it better than the JD VR?

Jim - I can't speak for the JD regulator ... don't know about its specifications. However, I can state the Silent Hektik is rated for 47 amps at 14 volts and that means it will not be hanging on the ragged edge of failure while in use in the RV-12. I purchased the unit about a year ago and believe it was somewhere around $180 plus a little for shipping.

Below are a couple of photos of the unit ... you can tell just by looking it is designed to dissipate some heat.
DSC01181.JPG


DSC01183.JPG
 
John - please give us an update

This is extremely interesting to me. Assuming that you have more than a years experience with this VR, could you please give us an update on you experience with it and your opinion as to whether or not this is the answer to the VR problem. Thanks, Ed Eliot
 
John-G;
Would you share the name of the motorcycle dealer who delivered the Silent Hektik regulator ?.

thx
Tom O.

Tom - I used the WEB address that was a response to one of Jetguy's post in the following link. My contact there was Ian. [email protected]

http://www.vansairforce.com/community/showthread.php?t=130921

Ed - Sadly, I can't give you an update on how well the regulator performs because I have not installed the regulator yet. I was planning on installing it prior to the airworthiness inspection but ran out of time, so just temporarily threw in the Ducati regulator ... didn't even place the wires in the connector block because I knew it would not be a permanent install. I plan on installing the Silent Hektik unit between now and Spring thaw and keep the Ducati as a backup.

At this point in time I make sure the battery is charged prior to engine starts so the load on the Ducati regulator is as minimal as it can be, without the need to charge up the battery on top of supplying the avionics and lighting power.

Hopefully Jetguy can chime in and give us a performance review ... he should have more than a year on the Silent Hektik unit by now.

Happy flying,
 
http://www.vansairforce.com/community/showpost.php?p=1083293&postcount=7

Read the links in this post. It should be required reading for all 12 owners.

It has a temperature vs load chart, and a circuit diagram.

Heat HEAT HEAT

Do what ever is possible to keep that sucker cool. And thermocouple it to ensure it really IS cool. Then it should last 4000 hrs. My Kubota VR (similar) did.

Yeah, you would think heat is the main reason. For what it's worth, my Duc VR died at around 87 hours and I found the temperature sticker on it never exceeded 160-170F. That's the maximum it should be able to take, so no reason to die prematurely. I have 1 SkyView display and a lighting kit but rarely using more than the position lights.
I put the Silent-Hektik VR in it and it's working great for 100 hours in the same temperature range.

Details of the swap are here.
 
There was a small issue with the leads though, apparently the regulators are not available any longer with spade leads on the regulator ... now the regulator comes with wires coming out of the regulator with bullet connectors attached to the wires, not a big deal I'll just cut off the bullet ends and replace them with spade terminals for compatibility with the ends on the Rotax engine's wires.

Hm, when I ordered mine 2 years ago it seemed the F4112 was the drop-in replacement for the Duc VR with spades. Now, I see on their website that the drop-in replacement is the F4118, still showing spade connectors with improved charging electronics that support Li-Pos in addition to lead acid batteries.
Here's their translated web page for the Rotax VR: English translation
 
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Silent Hektik F4118 availability

I posted this under the Silent Hektik topic--reposting here:

The motorcycle shop in Great Britain which has been selling the SH regulator is now selling them on eBay--a bit pricey when adding in the postage, but at least they are available without having a friend pick one up for you in Europe:

http://www.ebay.com/itm/262818488520?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

I got one on order from them a few days ago, and, coincidentally, my Ducati just failed with about 120 hours on it--100 of it in the firewall forward location, and the remainder in the relocated position in the cockpit. Fortunately I have a spare Ducati unit to put in place until the SH unit arrives. The new Ducati will then return to its spare status. Has anyone come up with a nicely derogatory interpretation of DUCATI as an acronym, similar to "Fix It Again, Tony" for FIAT?
 
VR.....just some thoughts

I've been toying with the VR issue. Not really to fond of having to mess with one on a long cross country.

What about installing some rivnuts under the avionics bay shelf below where the fan blows exhaust air out....invert the regulator so cooling fins are directly underneath fan on a "U" bent shelf bracket which is bolted into rivnuts. Wounldn't have to remove avionics bay cowling cover to change VR, if need should arise.

I'm going to give it a try..along with installing a SH vr....everything I've read points to temp being the cause of failure.
 
Sounds interesting, but not sure it will do much. I added a small aluminum shroud to generally route the avionics compartment fan exhaust (like warm baby's breath) towards the VR fins - not sure this is worth the effort. I may add a little external air scoop and ducting just ahead of the right-side cockpit air vent to blow a bit of outside air at the VR. Use nutplates on your in-cockpit VR and carry a spare VR. ;)
 
Ducati regulator failure causes

I've spent some time tearing apart Ducati regulators trying to answer this question. My day job is running a small electronics manufacturing company so we deal with failure analysis (fortunately not often!)

The regulator is marginal but will work fine and last a long time at full output if it's appropriately cooled, and was assembled correctly. Every failure I've seen was due to one or both of those assumptions being false. Most builders fail to route cooling air over the regulator, so the case gets hot and internal heat builds up. And, each of the three failed regulators I have taken apart had a cascade failure mode where contamination (dirt or oxidation) in solder joints caused them to fail -- resistance of the joint is increased because of decreased cross-sectional area, which causes the joint to heat up, sometimes enough to melt the solder, and soon to contribute more contamination to the joint.

It's not only the solder connecting the semiconductors but also the installation of the connector to the outside world where it's soldered to the PC board. One had gotten so hot that the insulation on the yellow wires was partially melted as much as 6 inches away from the regulator. If you see any discoloration of those wires, they are probably getting hot at the connector.
 
dljosephson -

Have you disassembled a JD VR to validate construction quality?

The Silent-Hektik VR is nearly $300... You can buy a lot of JD VR's for that price and keep the new administration happy that your not contributing to the trade deficit. :D
 
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dljosephson -

Have you disassembled a JD VR to validate construction quality?
I don't know if he has, but I have. It was typical of low end Chinese manufacturing, which is to say the actual PCB assembly was OK, but it was done with no apparent comprehension of the design. The PCB was simply dropped in place and potted... with the high power semiconductors on the board surface FACING AWAY FROM THE HEAT SINK. So that nice big chunk of aluminum is doing nothing other than, in typical fashion for parts sourced from some places, making it look like the original without actually working.

IMG_1341-400x300.jpg


The Silent-Hektik VR is nearly $300... You can buy a lot of JD VR's for that price and keep the new administration happy that your not contributing to the trade deficit. :D
I'm balking at that price too, but buying a lot of JD-style regulators means replacing a lot of them as well. I'm not a big fan of just waiting for electrical components to fail in flight. For $300 I can gut the Chinese regulator and build my own into the case.
 
So, I guess the next question is - what is the field reliability of the JD VR in RV-12's?

I don't know if anyone has reported a failure.
 
So, I guess the next question is - what is the field reliability of the JD VR in RV-12's?

I don't know if anyone has reported a failure.
See post above -- mine failed after around 10 hours - and I don't have lights or dual screens. I'm very glad I didn't have it mounted inside the cockpit when it did, by the way. Even with it mounted forward of the firewall there was a strong and distinct burning smell.
 
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Gess guys...it would be worth $500 to have a vr that would be dependable and not fail (it is a rather important piece of equipment in the aircraft)...

Can't believe someone can't provide a fix????
 
That Silent Hektik is looking more attractive all the time. I went and flew today; the Ducati is putting out a whopping 13.1 V at 4500 RPM cruise. I brought the carcass of the JD replacement home from the hangar, I'll pull it apart further and see what I find.
 
I had an e-mail with the request if I can buy the regulators on this side of the ocean (I'm living in the Netherlands).
I mailed Silent Hektik with a request for a quotation for an initial order for 10 regulators (F4118). In that case the price will be $174,-/unit including shipping to the Netherlands.
My wife and I are working for an airliner so one of us can take them to the USA when we have a flight to the States and drop them off at FedEx or DHL. Shipping max $20? So total around $200,- (regulator + shipping + PayPal).

List complete for 10 units (30/01/2017)
Just back from DXB, will try to finalize the order this week before my next flight.
 
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Install Silent Hektik with heat sink compound

For those of you RV-12 owners that are about to switch over to the Silent Hektik regulator I have a couple of suggestions.

Heat is the killer of electronics so to help mitigate the affects of heat you will want to do yourself and the regulator a favor and slather a thin film of heat sink compound onto the entire bottom of the regulator prior to bolting it down. A glad bag over the finger will work well for spreading a smooth thin coating onto the regulator bottom. The heat transfer paste that is used on the Rotax's spark plugs will work well for this application if you have it ... else, get some thermal paste from Radio Shack or any electronics supply house. Artic Silver ( a high quality microprocessor heat transfer compound ) would probably also be a great choice for this application as long as it was spread thinly.

If mounting the regulator on the inside of the cockpit, be sure to remove all paint and/or primer from the bottom of the instrument panel base where the regulator will mate.

If you are keeping the regulator on the firewall shelf, consider moving it more to the left side of the firewall shelf to keep it away from the outflow from the coolant radiator and then run a scat tube to the lower cowling to get plentiful cool air from the air duct ahead of the radiator.

My two Lincolns
 
Joeri,
Please add me to the list. Let me know how you would like payment. My email is alex at fpcounsel dot com.
Thanks,
Alex
 
I know that this has been hashed out a lot - but - I can't help but wonder what it about the RV-12 electrical system that is causing some VRs to die quite young?

Really? Something is wrong - what is it?

One of the Kitplanes editors asked me to address the problem, so here goes. I need somebody on this forum with direct experience and a bit of technical knowledge to describe for me exactly what this "regulator" does. Seems to me that it is taking a raw AC waveform from a generator, rectifying it into DC, and then providing that for your DC power source.

The SUPPOSITION is that heat is the problem. I'd like some data on why you all think this, rather than some sort of spike that kills the regulator from the output, but that's just me trying to see if it is the belt or the suspenders that are letting the jeans fall off.

If I can solve the problem, I think I can do it for less than a hundred bucks ($100) in parts, but y'all have to spoon feed me as to what size I can have, what the maximum temperature I can expect where this sucker is mounted, and all that good stuff .... MEASURED and not SEWAGed.

Anybody up for this?

Jim
 
People to talk with:
Gilles Theseus (France ?)
Mike Miller
Link to Contrails Rotax Ducati
There are two opinions about the failures: vibration and heat.
Ducati Schematic The schematic may have changed over time.
The generator is permanent magnet, single phase (dynamo).
The Ducati rectifier/regulator changes the AC to DC and regulates the output voltage. Terminal "C" both enables the regulator and senses aircraft electrical system voltage.
 
One of the Kitplanes editors asked me to address the problem, so here goes. I need somebody on this forum with direct experience and a bit of technical knowledge to describe for me exactly what this "regulator" does. Seems to me that it is taking a raw AC waveform from a generator, rectifying it into DC, and then providing that for your DC power source.

The SUPPOSITION is that heat is the problem. I'd like some data on why you all think this, rather than some sort of spike that kills the regulator from the output, but that's just me trying to see if it is the belt or the suspenders that are letting the jeans fall off.

If I can solve the problem, I think I can do it for less than a hundred bucks ($100) in parts, but y'all have to spoon feed me as to what size I can have, what the maximum temperature I can expect where this sucker is mounted, and all that good stuff .... MEASURED and not SEWAGed.

Anybody up for this?

Jim
Jim, there's a schematic posted (as noted above) and there are similar devices in widespread use, mostly in motorcycles it seems. It's a rectifier-regulator, Google is your friend once you use that search term. I'm no EE, just a hack with a soldering iron... but if I were describing the circuit I think I'd say it's an odd hybrid of bridge rectifier and sort-of-switching regulator.

The older designs use SCRs in the rectifier, triggered when the voltage exceeds a set value to short the incoming AC voltage to ground. Talk about your brute force regulation, right? The newer ones use MOSFETs.

The Ducati failure modes are pretty well documented. My "replacement" went poof because of really poor physical design, a defective part (surprise, surprise) or both. I'm guessing thermal runaway caused by a lack of heat sink and a mass of rubber thermal insulation around the critical parts. The power components are surface mounted on a PCB, inside a nice massive heat sink casting... but the PCB is glued to the heat sink, not the components, slo they've got good thermal insulation from the heat sink. ::rolls eyes:: For $30 I'm not inclined to spend too much time analyzing it, but you're welcome to the corpse if you want it.

I was tempted to build something new in the case of my deceased Chinese John Deere "replacement" regulator, but my appetite for stress testing in my airplane is not too great - and my desire to set up a meaningful test rig is even less. This is a rare case where I'm willing to spend a few bucks to avoid screwing with it. I'll be installing one of the German made Silent Hektik regulators, hopefully before my Ducati gives up the ghost. It's running less than 13.5 or so in flight lately, I think its days are numbered. I plan to un-pot it and have a look once I have a stable replacement in service.

73 de N0XAS...
 
FYI

One of the Kitplanes editors asked me to address the problem, so here goes. I need somebody on this forum with direct experience and a bit of technical knowledge to describe for me exactly what this "regulator" does. Seems to me that it is taking a raw AC waveform from a generator, rectifying it into DC, and then providing that for your DC power source.

The SUPPOSITION is that heat is the problem. I'd like some data on why you all think this, rather than some sort of spike that kills the regulator from the output, but that's just me trying to see if it is the belt or the suspenders that are letting the jeans fall off.

If I can solve the problem, I think I can do it for less than a hundred bucks ($100) in parts, but y'all have to spoon feed me as to what size I can have, what the maximum temperature I can expect where this sucker is mounted, and all that good stuff .... MEASURED and not SEWAGed.

Anybody up for this?

Jim

Jim, this link was buried and you may not have seen it or it may be of no help. It may provide a contact for you to discuss with a peer.

http://contrails.free.fr/elec_ducati_en.php

EDIT: Another EE experimenter on the VR - Very good - you will have to join the forum to see the results. HERE
 
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jweir43

Perhaps you can also compare the Ducati to the John Deere AM101406 regulator that many of us RV-12 guys have substituted.
 
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
 
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.
 
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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
 
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.
 
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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?
 
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.
 
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.
 
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