Voltage regulator on engine side?

[Esser]

Sorry for the load of electrical posts but I’ll be bugging everyone for a bit.

Is there an issue with putting the voltage regulator on the engine side of the firewall? Or is my only option to extend the shielded wires off the internal alt.?

[jrevens]

I believe that many people have located them on the engine side. Perhaps there is more potential heat there, especially after shut down, but that is mitigated by air flow when the engine is running. Air flow is good. I put my Silent Hektik unit behind the firewall and extended the leads. That's where my over-voltage relay and capacitor are, so it made more sense to me to group those together, wiring wise, and the SH unit has a higher amperage rating as well as more heat-sink area than the Ducati.

[AirFox]

I put my voltage regulator on the firewall above the Battery so it is in the air flow. It is working out much better than behind the firewall. Also the Rotax connector has caused some people issues. I just installed connectors right to the blades on the voltage regulator.

good luck Josh.

[jiott]

John, where and how did you get your hands on that Silent Hektik regulator. You must know someone who bought it for you in Europe, the sent it to the US privately?

[jrevens]

John, where and how did you get your hands on that Silent Hektik regulator. You must know someone who bought it for you in Europe, the sent it to the US privately?

Yes, I think I wrote about that on my build thread. I have a friend who goes to Holland frequently - his wife is from the Netherlands, and he knew a RANS builder there who was willing to buy one and ship it here.

[dcsfoto]

put it on the engine side.

if the regulator burns out the fumes are toxic

D Kelm

[Av8r3400]

I have seen several burn out on many planes and not one has made any "toxic" fumes.

I just replaced the one in the Mangy (inside the cabin away from the engine heat). No fumes.

[Floog]

3 years ago I 'smoked' a Ducati inside the firewall. The cause was a loose ring shank terminal on the C to L circuit. Though the smoke in the cockpit got my attention, there was no evidence of overheating. The regulator and wiring looked like new. Weird. Recently, I added a 40 amp alternator in parallel with the existing Rotax system. It's now a 'backup' to the external alternator. With all the extra power, I'm considering a seat warmer and A/C (:

[jiott]

I also had a Ducati fail, mounted on the cockpit side of the firewall, with no toxic fumes.

[Rodney]

Also had the Ducatti regulator inside the cockpit fail. No toxic fumes I was aware of.

In doing some research on the Vans RV-12 forum, ( they mount their regulators on the engine side of the firewall). I came to the conclusion that heat may be a factor contributing to failures.

I replaced my regulator with one from NAPA and mounted a 5 inch dia. 12 volt cooling fan about an inch away from the regulator. Fan wired into master switch.

That was a little over a year ago and so far, no problems

Rodney

[Esser]

I ended up putting my regulator right near the firewall but aft so it is in the cockpit.

[Av8r3400]

I replaced my regulator with one from NAPA and mounted a 5 inch dia. 12 volt cooling fan about an inch away from the regulator. Fan wired into master switch.




What type of regulator did you use from NAPA?

[Rodney]

The NAPA part number is SME 7068102

My store did not stock it, but ordered it in, in about three or four days.

The new regulator has five tabs instead of the six on the Ducatti.
Wiring sequence is as follows

Regulator. = Wire

B. = White
AC. = Yellow
AC = Yellow
L = Orange/Green
IGW = Orange/Blue

The extra white wire is tied off and not used

Voltage output at cruise is 14.7 volts

Regards
Rodney

[Floog]

Cost of NAPA reg?

[Av8r3400]

Looks like about $90 for the John Deere lawnmower (NAPA) regulator.

[Floog]

Thank you!

[Rodney]

Also, I believe the NAPA regulator has a lifetime warranty. It is rated at 20 amps.

Ok, I have a question for you electronic guys that understand this stuff. :rolleyes:

I read on another forum, that: (Hope it's ok to post this - not sure I understand enough about this to repeat it accurately. My son is the electrical engineer - not me! :confused:)

'The Rotax alternator is a permanent magnet design meaning that the field is produced by permanent magnets moving past the coils. This differs from the typical automotive type with the method required to regulate voltage. With the automotive type, the regulator varies the field voltage to increase/decrease the output current. With the permanent magnet type the alternator is continuously producing maximum power. These systems require a regulator that can add resistance between the alternator and the battery. The resistor bank is designed so the resistance can be varied and essentially is burning off the excess power that would otherwise overcharge the battery.
So, to reduce the work that the regulator is required to do it would actually be better to have all current consuming devices powered up (lights, radios, iPad charger and so on). The more power you are using, the less the regulator has to dump into the resistor bank, therefore the less heat the regulator has to get rid of. It becomes obvious that typically the regulator will be producing heat and will most certainly last longer with a supply of cooling air passing through/over the heat sink fins. Running with your landing lights on will take a load off the regulator, not add to it. Adding cooling air flow will extend the life of the resistors in the regulator.
I hope this helps understand some of the differences of the Rotax electrical system."

Is this right??? So it's better for the regulator to have all the electrical load one can put on it - and that will reduce the internal heat, or the heat that the regulator has to dissipate?

Maybe jrevens who seems to really know this electrical stuff can jump in here and educate me - well maybe all of us. Anything we can do to prolong the life of these regulators would be advantageous.

We know the "what" - and that is the Ducatti regulators are failing. I believe the consensus opinion seems that these are heat related failures.

Maybe this explains the "why." Not enough load on the regulators.

Thanks
Rodney

[efwd]

That seems to make a bit of sense to me but I hate electricity and don't understand it at all. I see my regulators and there is no indication that there are any cooling fins whatsoever.
Eddie

[jrevens]

Rodney,

I don't know much about these regulator/rectifiers, but I don't think that explanation is correct. I don't believe that there is a "resistor bank" that "excess power" is dumped into. There is obviously a lot of misinformation on the internet about how they actually work, as people who seem to be much more knowledgeable than I have completely differing opinions about exactly how they do work, and they can't all be right, obviously. I do believe that the Ducati is not a shunt or series type regulator, but possibly some type of switching unit. I also believe that failures seem to have been temperature related, and that there is the possibility of quality control or design issues also with the Ducati, but I would not be able to personally assert that as a fact. The units have been bench tested by some who say that there is not more heat generated when the unit is under less load, but just the opposite. Others claim otherwise. I know that the Silent Hektik units like I have are considered a more modern/robust design (whatever that means) by many, are rated for higher amperage, have a better heat sink design, and seem to have an excellent track record so far. I know nothing about the John Deere unit, but it seems to me that if they were a superior replacement that there would be all kinds of info about that on the internet forums and they would be very prevalent on the many thousands of Rotax engines. But maybe not. Bob Nuckolls could possibly shed some light on this subject, and I know he has some interest in it, but I haven't seen anything about it from him.

[Rodney]

Thanks John. Always appreciate your insight.

[jrevens]

FWIW... I can confirm that the Ducati regulator/rectifier is indeed a switching type regulator. Additionally, it obeys ohm's law - the more current that flows, the warmer it gets. My thanks to Bob Nuckolls and others on the AeroElectric forum. Here is the schematic of the circuit -