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View Poll Results: On your current airplane, how reliable is/was your alternator
I have used an automotive alternator and had no failures in its first 250 hours. 108 25.96%
I have used an automotive alternator that failed within the first 250 hours. 24 5.77%
I have used a Plane Power alternator and had no failures in its first 250 hours. 127 30.53%
I have used a Plane Power alternator that failed within the first 250 hours. 49 11.78%
I have used a B&C alternator and had no failures in its first 250 hours. 105 25.24%
I have used a B&C that failed within the first 250 hours. 3 0.72%
Voters: 416. You may not vote on this poll

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  #151  
Old 08-21-2018, 02:58 PM
rv7charlie rv7charlie is offline
 
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Location: Pocahontas MS
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One driver of IR alternator failure rates in homebuilts is this:

The alternators typically used by homebuilders are designs originating in the 1970s through the 1990s. Few if any of these alternators have any kind of 'load dump' protection. Not a factor in cars; there's no way to do a load dump in that application. But homebuilders typically come from the certified world, where the alternator has a separate switch from the master. There are many ways to wire an a/c, and most of them provide ways to remove all loads from the alternator at the flip of a switch. Not an issue if the (external) regulator powers down with everything else and the field collapses. But with internal regulation, if the alternator is heavily loaded and all loads are instantly removed, the internal regulator can't track quickly enough to lock the output voltage at the setpoint. It can spike upward high enough to exceed the breakdown voltage of the semiconductors in the regulator, which effectively kills the alternator. Note that this is *not* a defective alternator design. It *is* defective operating technique by pilots. I have 'defectively' operated one that way myself, when I didn't know better.

I suspect that if you removed installation/operator errors, the IR regulator reliability numbers would approach the B&C numbers.

Charlie
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  #152  
Old 08-21-2018, 03:48 PM
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rv6ejguy rv6ejguy is offline
 
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Location: Calgary, Canada
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In our recent REAL WORLD testing of a mid '90s Denso and Hitachi IR alternators, no damage was done with the battery completely disconnected, up to 60 amps load applied via a load tester and quickly taken on and off dozens of times.

IMO the #1 cause of IR alternator deaths is the substitution of inferior, aftermarket regulators, bearings etc. into an otherwise virtually bulletproof design.

I've shut off my Denso IR alternator in my 6A HUNDREDS of times over the last 15 years while it's outputting charge current- still working fine. https://www.youtube.com/watch?v=NvQR...CCGoQ&index=15
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Turbo Subaru EJ22, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 424.4 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
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  #153  
Old 08-21-2018, 04:00 PM
rv7charlie rv7charlie is offline
 
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Hi Ross,

I'm not sure we're talking about the same thing. Yours has a control terminal that actually tells the regulator to shut down; not all alternators from that era will shut down when power is removed from that terminal.

What I was describing is literally disconnecting the B lead while the alternator is heavily loaded. Some models will fail, some won't, and some might. Your model can obviously handle it, but not all will (or did).

Charlie
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  #154  
Old 08-21-2018, 04:20 PM
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rv6ejguy rv6ejguy is offline
 
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1992 Hitachi IR, loaded up to 60 amps output (full rated current), load removed, dozens of times, no damage, no battery connected to absorb any spike. Worst case scenario.

Speculation proves little. I've asked people in these alternator threads to actually do the tests (load, dump, temperature) and video it or at least document it so we can all learn something. Folks will have a lot more people listen to what they have to say when they present real world data rather than speculation.

Show us that this will fry X alternator and we'll certainly accept it. Until then, I remain unconvinced.

"The world is changed by your example, not by your opinion" Paulo Coelho
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 424.4 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm



Last edited by rv6ejguy : 08-21-2018 at 04:52 PM.
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  #155  
Old 08-21-2018, 04:56 PM
rv7charlie rv7charlie is offline
 
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OK, you win. It's a myth.

https://www.google.com/search?q=alte...hrome&ie=UTF-8
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  #156  
Old 08-21-2018, 06:21 PM
AntonioRV7 AntonioRV7 is offline
 
Join Date: Aug 2018
Location: São Paulo
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Default Plane Power Alternator Output

I was checking old photos and videos to verify the voltage displayed in my Dynon D120.

I never close monitored the voltage reading, just spot checks during normal operations, and i could swear that it was steady at 14.1 or 14.2V all times!!

But, i was wrong... when watching some videos recorded 4 years ago (Note: my alternator, battery, and all other electrical components are all the originally installed, never replaced and all of then are 6 years old!!) i got surprised to realize that the voltage "floating" between 13.6 and 14,2V occurs very often!!!

Despite it's not a desired reading, my battery is 6 years old (concorde) and still works fine!!!!
Never had problems or difficult to crank the engine, even with more than 30 days flight interval!!!

So... this "Gremlin" appears to be innofensive!!!

In any case, i'll run a complete connections check up... and keep flying!!!
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  #157  
Old 08-22-2018, 10:06 AM
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db1yg db1yg is offline
 
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Posts: 611
Default Auto Alternator Reliability

My experience is with a $100 ND 55 amp internally regulated auto alternator that had been rebuilt by Bosch. It is the model that was originally on the 1987 Suzuki Samirai. It was rock solid at 14.2 volts until around 400-450 hrs and then the voltage started varying somewhat. I took it off, took it to an "off road" alternator shop and they replaced the bushings (which really did not need replacing but since we had it apart . . .) and the internal regulator (they probably installed a cheap one)--at the outrageous expense of $65. It was again rock solid but only for around 100 hrs and again some (+ or - 1 volt) voltage variation. I replaced the entire unit with another $120 ND 55 amp unit rebuilt by Bosch and all is good again. I would conclude that the quality of the internal regulator is critical to the reliability of the unit. At only $120 for the unit I intend to replace it or rebuild it myself (using quality parts) every 500 hrs. BTW, I do not have a blast tube to the unit.

YMMV

Cheers,

db
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  #158  
Old 08-22-2018, 01:45 PM
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AlexPeterson AlexPeterson is offline
 
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ND IR 40 amp. Ran it 1300 hours, 10 years with no problems. Overhauled engine and decided to put a new ND IR 40 amp in. It's been working about 350 hours so far. Old one is spare. Blast tube cools the back end where regulator is, another tube blowing on stator section.
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RV6A N66AP 1600+ hours
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  #159  
Old 08-22-2018, 09:32 PM
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db1yg db1yg is offline
 
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Default Blast Tube

Probably should install a blast tube to the IR on the alternator---Heat and cheap parts be the enemy!!

Cheers,

db
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