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Thread: Voltage regulator on engine side?

  1. #11
    Senior Member Esser's Avatar
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    Default Re: Voltage regulator on engine side?

    I ended up putting my regulator right near the firewall but aft so it is in the cockpit.
    ------------------
    Josh Esser
    Flying SS7
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    Edmonton, AB, CWL3

  2. #12
    Super Moderator Av8r3400's Avatar
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    Default Re: Voltage regulator on engine side?

    Quote Originally Posted by Rodney View Post
    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?
    Av8r3400
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  3. #13
    Senior Member Rodney's Avatar
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    Default Re: Voltage regulator on engine side?

    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

  4. #14
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    Default Re: Voltage regulator on engine side?

    Cost of NAPA reg?

  5. #15
    Super Moderator Av8r3400's Avatar
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    Default Re: Voltage regulator on engine side?

    Looks like about $90 for the John Deere lawnmower (NAPA) regulator.
    Av8r3400
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  6. #16
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    Default Re: Voltage regulator on engine side?

    Thank you!

  7. #17
    Senior Member Rodney's Avatar
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    Default Re: Voltage regulator on engine side?

    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.

    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! )

    '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
    Last edited by Rodney; 10-25-2017 at 08:29 PM.

  8. #18
    Senior Member efwd's Avatar
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    Default Re: Voltage regulator on engine side?

    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

  9. #19
    Senior Member jrevens's Avatar
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    Default Re: Voltage regulator on engine side?

    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.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
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  10. #20
    Senior Member Rodney's Avatar
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    Default Re: Voltage regulator on engine side?

    Thanks John. Always appreciate your insight.

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