---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Mon 08/19/13: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:29 AM - Re: Re: AeroElectric-List: Re: Rotax 912 UL alternator drop-out (FLYaDIVE) ________________________________ Message 1 _____________________________________ Time: 02:29:52 AM PST US Subject: Re: RotaxEngines-List: Re: AeroElectric-List: Re: Rotax 912 UL alternator drop-out From: FLYaDIVE Good report Paul. A practical approach has prevailed. Now since you know 10 Amps will overload the system and 5 to 6 Amps is borderline for an overload. The next thing to do is COOL the unit and apply 5 to 6 Amps and see if it stays online. If it stays online you now know cooling is required. Barry On Sun, Aug 18, 2013 at 11:57 AM, Paul Kuntz wrote: > Several inputs suggested checking the connections on the leads coming from > the alternator, and checking the system ground connections. I checked the > faston-type alternator lead connections, which were clean and tight. I > checked all of the ground connections, which were also tight. Yesterday I > went up for a test flight and confirmed the symptoms under varying system > loads. The normal system voltage with alternator on line is 13.8 volts, > which is consistent with what others are reporting for the Rotax Ducati > regulator. I see a max load of 10 amps with everything running, so I am > satisfied that the total load is well within the standard Rotax system > capacity. I also observed that the system voltage drops to 13.5 volts at > the 10 amp max load, which seems abnormal. Under this max load, the > alternator dropped out after a few minutes, indicated by system voltage > dropping to around 12.5 volts -- consistent with fully charged lead-acid > battery. > > When I reduced the load to 3 amps, which is my practical minimum (one > Dynon display, radio and transponder), the alternator came back and stayed > there, with system voltage at the normal regulator set point of 13.8 > volts. > > I repeated this experiment a few times for various loads, finding that a > total load above 5 or 6 amps will cause the alternator to drop out after a > few minutes, and that it will come back when the load is reduced to 3 > amps. > > I am pretty well convinced that my voltage regulator is bad. I did learn > from comments on this issue that Van's includes a voltage regulator cooling > kit with its lighting kit for the RV-12, consisting of a length of plastic > tubing that connects from the air intake duct to a shroud over the > regulator, providing a direct blast of cooling air to counteract the > increased electrical load of the lighting. So there is certainly > indication that the Ducati regulator is susceptible to overheating under > load. The RV-12 regulator is on the engine side of the firewall, however, > and mine is on the cabin side. At 10 amps with the regulator mounted in > the cockpit environment, I'm thinking the regulator should be able to > handle the load without supplemental cooling. Others have noted the > not-so-good reputation of the Ducati regulator, but there are thousands of > them in service on Rotax engines worldwide, so rather than tackle a > reconfiguration of my regulator and wiring installation at this point , I > ordered a replacement Ducati from Lockwood Aviation and will see how it > goes. I also ordered a overvoltage protection module from B&C, since the > Pipistrel electrical system does not include one. I'll install it with the > new voltage regulator. > > I'll report my findings after installing the new regulator. > > Paul Kuntz > > > On Sat, Aug 10, 2013 at 10:21 PM, Paul Kuntz wrote: > >> Thanks for the tips, everyone. I concur with Bob that my Ducati >> regulator is done for and should be replaced. I will take a look at the >> Schicke unit that Peter mentioned. >> >> Cheers, >> Paul Kuntz >> >> >> On Friday, August 9, 2013, Robert L. Nuckolls, III wrote: >> >>> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" < >>> nuckolls.bob@aeroelectric.com> >>> >>> At 12:55 PM 8/9/2013, you wrote: >>> >>>> Thanks for the tip. I'll check this cooling shroud idea. I'm also >>>> wondering if my regulator has already been compromised. Any opinions on >>>> what my repeated fail/recover situation indicates? I would guess that it >>>> cycled between failed and recovered 8 or 10 times before we established a >>>> state where it stayed on line, limited to a total current draw of 3 amps. >>>> >>> >>> If your regulator can't carry 10A without cooling, it's >>> probably broke. A functional part should be capable of >>> rated output for the alternator which is on the order >>> of 18A. I've not heard of any mass-movements to forced >>> air cool these regulators. >>> >>> >>> >>> >>> Bob . . . >>> >>> ====**==============================**= >>> -List" target="_blank">http://www.matronics.com/** >>> Navigator?AeroElectric-List >>> ====**==============================**= >>> http://forums.matronics.com >>> ====**==============================**= >>> le, List Admin. >>> ="_blank">http://www.matronics.com/**contribution >>> ====**==============================**= >>> >>> >>> >>> > * > > * > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rotaxengines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RotaxEngines-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/rotaxengines-list Browse Digests http://www.matronics.com/digest/rotaxengines-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.