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914 alternator/regulator

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ksiggery(at)mac.com
Guest

Posted: Mon Feb 11, 2008 1:25 pm Post subject: 914 alternator/regulator

Before we start the nightmare process of replacing the alternator on  

914-powered G-ROOV could anyone point us towards possible other  

problems with the electrical system recently identified:



Before start, master on, we see I=0 amps, V=11.



Engine off, loaded I=-5, V=11.



Engine running (essentials on) I=-4, V=11



Engine running (full electrical load) I=-5, V=11



Besides the fact we should be seeing 12V from the battery (we are  

charging it now) to my non-expert eye this would suggest alternator  

problems but strangely, the ‘idiot light’ is not illuminated which  

suggests that V (alternator) is greater than V(battery) i.e.: we do  

not have an alternator problem (unless the lamp has blown and we are  

being misguided).



Alternatively if the regulator is shot one would expect to see V  

falling as a function of load (I think) but this is not the  

case...although we believe the Ducati regulator is not exactly the  

best on the market and prone to quite frequent failure.



We are leaning towards simply swapping out the regulator at this stage.



Any thoughts most welcome.



thank you



Kevin Siggery

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topglock(at)cox.net
Guest

Posted: Mon Feb 11, 2008 2:18 pm Post subject: 914 alternator/regulator

This may be a over simplified answer, and I admit to being somewhat 

electrically deficient, but check the 30A main, inline fuse...



Jeff - Baby Blue

370 hrs



kevin siggery wrote:

 	  Quote: 	
		   

 

 Before we start the nightmare process of replacing the alternator on 

 914-powered G-ROOV could anyone point us towards possible other problems 

 with the electrical system recently identified:

 

 Before start, master on, we see I=0 amps, V=11.

 

 Engine off, loaded I=-5, V=11.

 

 Engine running (essentials on) I=-4, V=11

 

 Engine running (full electrical load) I=-5, V=11

 

 Besides the fact we should be seeing 12V from the battery (we are 

 charging it now) to my non-expert eye this would suggest alternator 

 problems but strangely, the ‘idiot light’ is not illuminated which 

 suggests that V (alternator) is greater than V(battery) i.e.: we do not 

 have an alternator problem (unless the lamp has blown and we are being 

 misguided).

 

 Alternatively if the regulator is shot one would expect to see V falling 

 as a function of load (I think) but this is not the case...although we 

 believe the Ducati regulator is not exactly the best on the market and 

 prone to quite frequent failure.

 

 We are leaning towards simply swapping out the regulator at this stage.

 

 Any thoughts most welcome.

 

 thank you

 

 

 

 Kevin Siggery

 

 

 

 

 

 

 269.20.2/1270 - Release Date: 2/10/2008 12:21 PM

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josok-e(at)ukolo.fi
Guest

Posted: Mon Feb 11, 2008 2:37 pm Post subject: 914 alternator/regulator

Hi Kevin,

This looks like one of the cells in the battery is defect. Do nothing before you have tried to charge the battery successfully with an external charger. If that does not give you 13 V at least, case closed, battery dead.  From the data you supply, it looks like the generator is charging anyway.



Regards,



Jos Okhuijsen

Visit -  www.EuropaOwners.org

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Gilles.Thesee(at)ac-greno
Guest

Posted: Mon Feb 11, 2008 5:27 pm Post subject: 914 alternator/regulator

kevin siggery a écrit :

 	  Quote: 	
		  

 Before start, master on, we see I=0 amps, V=11.


	


Not good : a properly charged battery reads 12.7-12.8 V.

11 V means a bad, bad battery state. A lead acid battery should not stay 

discharged for any length of time.



 	  Quote: 	
		  

 Engine off, loaded I=-5, V=11.


	


Strange, voltage should sag a little.



 	  Quote: 	
		  

 Engine running (essentials on) I=-4, V=11



 Engine running (full electrical load) I=-5, V=11



 Besides the fact we should be seeing 12V from the battery (we are 

 charging it now) to my non-expert eye this would suggest alternator 

 problems but strangely, the ‘idiot light’ is not illuminated which 

 suggests that V (alternator) is greater than V(battery) i.e.: we do 

 not have an alternator problem (unless the lamp has blown and we are 

 being misguided).




	


A correctly charging alternator/regulator should read 13.8-14.4 V



 	  Quote: 	
		   Alternatively if the regulator is shot one would expect to see V 

 falling as a function of load (I think) but this is not the case...


	


What I'do first is check the actual voltages with a portable voltmeter. 

Does your onboard really monitor what it is supposed to ?



Best regards,

-- 

Gilles

http://contrails.free.fr

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rampil

Joined: 04 May 2007
Posts: 870

Posted: Mon Feb 11, 2008 7:20 pm Post subject: Re: 914 alternator/regulator

Kevin,



Its really tough to give a literate answer to your question without

knowing a lot more about your charging and control circuit.  It sounds

like you used an established design, which one? What is in between

the alternator and the battery?



What is the voltage coming out of the alternator?

Have you traced the continuity of all wires/connectors? In the battery/

charging circuit there should only be fat wires and very low resistance

connections.  Is this the case in your aircraft?

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_________________
Ira N224XS

budyerly(at)msn.com
Guest

Posted: Tue Feb 12, 2008 3:44 pm Post subject: 914 alternator/regulator

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  As with the others who have answered, and they are correct...Here are a  couple more tidbits from some old questions I've answered befor:

  

  

 Quick and dirty for the Rotax mounted alternator/dynamo with external  regulator:

  

 Your field wire (C on the regulator) should read battery voltage with the  engine off.  If it does not that's the problem.  I have seen folks run  the alternator warning light in series with the C lead to the bus.  If the  light bulb fails, you open the field circuit and kill the regulator.  The  light circuit must be independent of the C lead connection to your bus.   Read the Rotax installation manual about the wiring requirements.

  

 Noting that the R and B+ leads (which are tied with the C lead, through the  panel usually) are reading battery voltage not 13.8 volts.  The  regulator is not putting out.

  

 Check your 30 amp circuit breaker/fuse coming off the regulator.  If  all the above are good, it's the regulator.

  

 Solid state rectifier/regulators put out about 12 volts on the L circuit  and as others have stated, the C circuit and R/B+ should read about 13.8.   If the diodes in the regulator fail, your L circuit will put out a voltage which  is about 1.3-1.8 volts less than your C circuit (same as your bus) and the fail  light will still not alert you to a failure as it is a 12 volt bulb...   Just like your car, the alternator light never comes on with this type failure,  only the battery failure is your indicator unless you monitor your volts and  amps.  

  

 Rarely do the Rotax coils in the dynamo fail,  It is most likely your  regulator.  

  

  

 Bud Yerly

 Custom Flight Creations

  

 [quote]     ---

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