---------------------------------------------------------- JabiruEngine-List Digest Archive --- Total Messages Posted Sat 04/25/15: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:19 AM - Re: alternator (Robert L Nuckolls III) 2. 05:41 AM - Alternator and gauge (BobbyPaulk@comcast.net) 3. 10:21 AM - Re: alternator (Rob Turk) 4. 03:40 PM - Re: alternator (Robert L Nuckolls III) 5. 03:42 PM - Re: alternator (Robert L Nuckolls III) ________________________________ Message 1 _____________________________________ Time: 05:19:32 AM PST US From: Robert L Nuckolls III Subject: Re: JabiruEngine-List: alternator At 15:51 2015-04-24, you wrote: CAMit for sure. As you say, they know the engine very well (they built them for many years) and today sell new engines with just this alternator setup. The aluminium spider needs to come off to change the belt, but that should be easy with the old alternator parts removed, and only a once-every-500-hours job. Rob On 4/24/2015 10:04 PM, BobbyPaulk@comcast.net wrote: List, I have two flights of about 30 minutes each on my Jabiru 3300 after some repairs and a couple of modifications. I changed the Alternator coils from 2 parallel circuits to 1 series circuit in accordance with Jabiru AVDALSR-087-1. It was working fine on the first flight and most of the second flight. Output was 14.6 volts while taxiing out. Halfway thru the second flight I turned on strobe lights to put a load on the alternator. I figure I was drawing no more than 11 amps. When I reduced power to enter downwind I smelled wires burning and noticed the battery voltage was down to 12.2. I turned off the strobes and landed. On inspection I found every other coil ( 6 ) in the alternator burned black and the alternator no longer worked. I am not going back with the original magnet / stator dynamo. My question to the list is whether to go with the CAMit alternator or the Rotec. I am leaning toward the CAMit version since they are very familiar with the Jabiru / CAMit Engine. Does anyone know if the belt on either one can be changed without removing the aluminum back plate? I was astounded to learn of what was touted to be a 'Jabiru recommendation' to series up the windings on the alternator for 'improved performance'. This has the effect of DOUBLING the alternator's AC output voltage . . . and yes, you'll see improved bus voltage readings at low rpm. To paraphrase the astute observation by one of my favorite authors, "There ain't no such thing as a free lunch." Moving from parallel connection to series connection doubles output voltage while cutting current delivery capability by more than 1/2. I.e. the POWER available from the alternator is unchanged but delivered at a higher voltage with lower current capability. There ARE regulator designs which would exploit virtually ALL the ENERGY available from the alternator at ANY practical voltage. In the legacy rectifier/regulator, current flowing in alternator windings is a mirror of that flowing out of the R/R. Rewiring the alternator while retaining the legacy regulator is all but guaranteed to produce the observed results. Going from parallel to series COMBINED with an upgrade of regulator technology would be a very good thing to contemplate. I'm having trouble believing that Jabiru engineers made such a recommendation; I'll bet it came from somebody down the distribution chain. In any case, ill-conceived. Replacing the alternator with a belt-driven, automotive derivative is also a practical option. Bob . . . ----------------------------- Bob Nuckolls AeroElectric Connection P.O. Box 130 Medicine Lodge, KS 67104-0130 Mobile: 316-209-7528 Web: http://aeroelectric.com ------------------------------ ________________________________ Message 2 _____________________________________ Time: 05:41:05 AM PST US From: BobbyPaulk@comcast.net Subject: JabiruEngine-List: Alternator and gauge Thanks to Dave and Rob for the info. I was aware of the pressure sensor reading on the very low end of it's range so I will set the low alarm to 1.5 PSI indicated and watch carefully. Also I will be ordering the CAMit Alternator. Thanks again bobby ________________________________ Message 3 _____________________________________ Time: 10:21:28 AM PST US From: Rob Turk Subject: Re: JabiruEngine-List: alternator Hello Bob, As astounding as it sounds, this mod indeed comes from the Jabiru factory themselves. Run a search for AVDALSR87 on Google and you will find the PDF listed as the first hit, direct from the Jabiru site. There is a second version (AVDALSR87-2) with a bit more explanation around, but nowhere does either version mention the loss of current delivery capability. It just touts the ability to charge the battery at near-idle speeds. Several people asked Jabiru about it and they claimed no loss of power from this mod. Considering the same current draw from the plane's electric system and the internal losses (= heat) in the alternator coil quadrupling at equal current draw with this mod (going from 1/2R to 2R), it is no surprise the coil will burn up. The belt driven alternative has two positive effects. First, there's more electrical power available, also at low idle speed. Second, the belt drive dampens torque pulses which helps keep the flywheel bolts intact. Definitely te way to go. Rob > I was astounded to learn of what was touted to be > a 'Jabiru recommendation' to series up the windings on the alternator > for 'improved performance'. This has the effect of DOUBLING the > alternator's AC output voltage . . . and yes, you'll see improved bus > voltage readings at low rpm. > > To paraphrase the astute observation by one of my favorite authors, > "There ain't no such thing as a free lunch." > > Moving from parallel connection to series connection doubles output > voltage while cutting current delivery capability by more than 1/2. > I.e. the POWER available from the alternator is unchanged but > delivered at a higher voltage with lower current capability. > > There ARE regulator designs which would exploit virtually ALL the > ENERGY available from the alternator at ANY practical voltage. > > In the legacy rectifier/regulator, current flowing in alternator > windings is a mirror of that flowing out of the R/R. Rewiring the > alternator while retaining the legacy regulator is all but guaranteed > to produce the observed results. > > Going from parallel to series COMBINED with an upgrade of regulator > technology would be a very good thing to contemplate. > > I'm having trouble believing that Jabiru engineers made such a > recommendation; I'll bet it came from somebody down the distribution > chain. In any case, ill-conceived. Replacing the alternator with a > belt-driven, automotive derivative is also a practical option. > > > Bob . . . ________________________________ Message 4 _____________________________________ Time: 03:40:55 PM PST US From: Robert L Nuckolls III Subject: Re: JabiruEngine-List: alternator At 11:00 2015-04-25, you wrote: >Hello Bob, > >As astounding as it sounds, this mod indeed comes from the Jabiru >factory themselves. Run a search for AVDALSR87 on Google and you >will find the PDF listed as the first hit, direct from the Jabiru >site. There is a second version (AVDALSR87-2) with a bit more >explanation around, but nowhere does either version mention the loss >of current delivery capability. It just touts the ability to charge >the battery at near-idle speeds. Several people asked Jabiru about >it and they claimed no loss of power from this mod. That's sad . . . but I guess not a great surprise. More and more companies have become so siloed and victim to the 'let's farm that out' syndrome that they loose command and control over critical aspects of their products. >Considering the same current draw from the plane's electric system >and the internal losses (= heat) in the alternator coil quadrupling >at equal current draw with this mod (going from 1/2R to 2R), it is >no surprise the coil will burn up. Agreed. >The belt driven alternative has two positive effects. First, there's >more electrical power available, also at low idle speed. Second, the >belt drive dampens torque pulses which helps keep the flywheel bolts >intact. Definitely te way to go. Yeah . . . but that PM alternator is so damned simple, elegant and robust. With the right electronics, it COULD be a significant ingredient in the recipe for success. Rotax too . . . I'm working on that . . . Bob . . . ----------------------------- Bob Nuckolls AeroElectric Connection P.O. Box 130 Medicine Lodge, KS 67104-0130 Mobile: 316-209-7528 Web: http://aeroelectric.com ------------------------------ ________________________________ Message 5 _____________________________________ Time: 03:42:38 PM PST US From: Robert L Nuckolls III Subject: Re: JabiruEngine-List: alternator Can anyone on the list give me a measurement of AC volts developed by the stock, parallel wound 3300 PM alternator at idle speed. Need to know what that speed is too . . . Bob . . . ----------------------------- Bob Nuckolls AeroElectric Connection P.O. Box 130 Medicine Lodge, KS 67104-0130 Mobile: 316-209-7528 Web: http://aeroelectric.com ------------------------------ ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message jabiruengine-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/JabiruEngine-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/jabiruengine-list Browse Digests http://www.matronics.com/digest/jabiruengine-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.