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How to check and alternator??

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mattreeves(at)yahoo.com
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Posted: Sun Aug 26, 2007 3:51 pm Post subject: How to check and alternator??

I have a 35 amp alternator and a 12 volt concorde battery and a Linear Voltage Regulator.  Lycoming 160hp 

   

  I have noticed the voltage reads just under 14 volts with the engine running.

   

  I also noticed the ammeter stays at zero unless I turn on something such as the nav lights or strobe lights.  Then it goes to the negative about 1/16 of an inch on a +40/-40 amp guage.  This remains the same even at high throttle settings.   No change at low or high power settings.

   

  I have a shunt.  I checked all the wiring an it is correct from Bingelis' book so I am wondering if my alternator is bad.

   

  What is the best way to check an alternator on an airplane?  Can't really take it to my neighborhood Advance AutoParts.  They might wonder what the big fan is for.

   

   Thanks!!



  [quote][b]

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nuckollsr(at)cox.net
Guest

Posted: Sun Aug 26, 2007 5:31 pm Post subject: How to check and alternator??

At 04:51 PM 8/26/2007 -0700, you wrote:



 	  Quote: 	
		  I have a 35 amp alternator and a 12 volt concorde battery and a Linear 

Voltage Regulator.  Lycoming 160hp



I have noticed the voltage reads just under 14 volts with the engine running.



I also noticed the ammeter stays at zero unless I turn on something such 

as the nav lights or strobe lights.  Then it goes to the negative about 

1/16 of an inch on a +40/-40 amp guage.  This remains the same even at 

high throttle settings.   No change at low or high power settings.



I have a shunt.  I checked all the wiring an it is correct from Bingelis' 

book so I am wondering if my alternator is bad.



What is the best way to check an alternator on an airplane?  Can't really 

take it to my neighborhood Advance AutoParts.  They might wonder what the 

big fan is for.


	


   Sounds like your alterantor is working. You can't have a bus votlage

   greater than about 12.8 if the alternator is not picking up ship's loads.

   Where is your ammeter in the system? If you have a -0+ reading ammeter,

   then it suggests a battery ammeter which is almost useless as a 

diagnostic tool.



   Suggest that you convert the ammeter to a +only alternator load

   meter. Then you'll see the alternator functioning as expected . . .

   picking up loads as they are added to the system.



   Bob . . .

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frank.hinde(at)hp.com
Guest

Posted: Mon Aug 27, 2007 6:30 am Post subject: How to check and alternator??

It depends on where your ammeter is connected as to what  info it is giving you. The best way to know if your alternator is working  adequately (i.e is making more current than is consumed by the electrical  devices in your airplane) is to watch the voltmeter.

  

 I.e if you turn everything on and it maintains above say  13.5V it working just fine.

  

 If it drops below 12.5V then it is either malfunctioning or  is undersized for the application.

  

 Sounds to me like your unit is working just  fine.

  

 Frank



   From:  owner-aeroelectric-list-server(at)matronics.com  [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Matt  Reeves

Sent: Sunday, August 26, 2007 4:51 PM

To:  aeroelectric-list(at)matronics.com

Subject: How to  check and alternator??

 

 I have a 35 amp alternator and a 12 volt concorde battery and a Linear  Voltage Regulator.  Lycoming 160hp 

  

 I have noticed the voltage reads just under 14 volts with the  engine running.

  

 I also noticed the ammeter stays at zero unless I turn on something such as  the nav lights or strobe lights.  Then it goes to the negative about 1/16  of an inch on a +40/-40 amp guage.  This remains the same even at high  throttle settings.   No change at low or high power settings.

  

 I have a shunt.  I checked all the wiring an it is correct from  Bingelis' book so I am wondering if my alternator is bad.

  

 What is the best way to check an alternator on an airplane?  Can't  really take it to my neighborhood Advance AutoParts.  They might wonder  what the big fan is for.

  

 Thanks!!

 

[quote]



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href="http://forums.matronics.com">http://forums.matronics.com



[b]

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mattreeves(at)yahoo.com
Guest

Posted: Mon Aug 27, 2007 8:34 pm Post subject: How to check and alternator??

Thanks for messages.  

   

  Here's the answer to your questions.

   

  I have a Chief Aircraft +/- 40 ammeter with a 40amp shunt.

   

  I think my alternator is 35 amps but can't remember - I'll have to look that up.  I am running Nav lights, strobe lights, wig wag lights, and a full Garmin stack so I'm thinking I may need to upgrade my alternator.  Will have to add that up before first flight to see the load.

   

  The ammeter has a positive and negative terminal on the back.  The positive is connected to to the small screw on the shunt which also has a large screw on the same side which is wired directly to the main power bus which also splits to a wire between the master and starter relay.    The negative side on the back of the ammeter is connected to the opposite small screw on the shunt which also has a large screw which is  wired through a 60amp circuit breaker to the main power bus.

   

  Kinda hard to explain without a picture.   I followed the Bingeles book when I wired it up a few years back so maybe I messed something up.

   

  I do know that the volt meter reads barely under 14 volts with the engine running.

   

  Thanks for the help!!!!

   

  Matt

   

  P.S.  My brother Danny has an RV-7A completely built in the basement of his house in Harrisburg, PA.  His MIL lives in the garage.   We got an estimate of $7000 to have someone dig a hole, cut the blocks out and put it all back together.  We are hoping for some suggestions as to how to get it out.  (The airplane - not the Mother-In-Law)



"Robert L. Nuckolls, III" <nuckollsr(at)cox.net> wrote:

  [quote]--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" 



At 04:51 PM 8/26/2007 -0700, you wrote:



[quote]I have a 35 amp alternator and a 12 volt concorde battery and a Linear 

Voltage Regulator. Lycoming 160hp



I have noticed the voltage reads just under 14 volts with the engine running.



I also noticed the ammeter stays at zero unless I turn on something such 

as the nav lights or strobe lights. Then it goes to the negative about 

1/16 of an inch on a +40/-40 amp guage. This remains the same even at 

high throttle settings. No change at low or high power settings.



I have a shunt. I checked all the wiring an it is correct from Bingelis' 

book so I am wondering if my alternator is bad.



What is the best way to check an alternator on an airplane? Can't really 

take it to my       Choose the right car based on your needs.    [quote][b]

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raymondj(at)frontiernet.n
Guest

Posted: Mon Aug 27, 2007 9:36 pm Post subject: How to check and alternator??

Matt,

  

 The only alternative I can think of besides taking  it appart is to bring it up through the floor and out a picture window.   Might be cheaper than all that digging and masonry work. Even cheaper if you're  a carpenter.

  

 Best of luck,

  

 Raymond Julian

Kettle River, MN

  

 "Hope for the best,

but prepare for the  worst."

  

 do not archive

 [quote]   ---

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nuckollsr(at)cox.net
Guest

Posted: Fri Aug 31, 2007 12:22 pm Post subject: How to check and alternator??

At 09:24 PM 8/27/2007 -0700, you wrote:



 	  Quote: 	
		  Thanks for messages.



Here's the answer to your questions.



I have a Chief Aircraft +/- 40 ammeter with a 40amp shunt.



I think my alternator is 35 amps but can't remember - I'll have to look 

that up.  I am running Nav lights, strobe lights, wig wag lights, and a 

full Garmin stack so I'm thinking I may need to upgrade my 

alternator.  Will have to add that up before first flight to see the load.



The ammeter has a positive and negative terminal on the back.  The 

positive is connected to to the small screw on the shunt which also has a 

large screw on the same side which is wired directly to the main power bus 

which also splits to a wire between the master and starter relay.    The 

negative side on the back of the ammeter is connected to the opposite 

small screw on the shunt which also has a large screw which is wired 

through a 60amp circuit breaker to the main power bus.



Kinda hard to explain without a picture.   I followed the Bingeles book 

when I wired it up a few years back so maybe I messed something up.



I do know that the volt meter reads barely under 14 volts with the engine 

running.



Thanks for the help!!!!


	


    The -zero+ reading ammeter is a BATTERY ammeter. When things

    are running normally (alternator carrying ship's loads and

    battery fully charged) then it SHOULD read at or near zero.

    Turn some things on with the engine not running. Let them run

    of the battery for 10 minutes or so. The ammeter should be

    showing a (-) value - energy is coming out of the battery.

    Take a voltmeter reading.



    Now, start the engine and turn the alternator on. Note the bus

    voltage. We would LIKE to see 14.2 to 14.6 volts but 13.8 or 13.9

    would still charge the battery.



    After the alternator comes on, if you see a rise in bus voltage,

    then the alternator IS working to some degree. Its set point may

    be too low . . . but it is working. Now the ammeter should show

    a decided (+) reading - energy is being stuffed back into the

    battery. Turn all the accessories off and observe the ammeter

    which should begin to move back toward zero indicating that the

    battery is topped off.



    For the moment, nothing you've written suggests that the system

    is seriously malfunctioning. It may need adjustment of voltage.



    Bob . . .

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mattreeves(at)yahoo.com
Guest

Posted: Sun Sep 02, 2007 3:31 am Post subject: How to check and alternator??

Hi Bob !!   

   

   

  Thanks for the help and suggestions !!  I really appreciate you and all I learn from you.

   

  So, I did exactly as you said, and you are 100% correct.   I left on a bunch of stuff for about 10 minutes, then started the plane and immediately noticed the ammeter was slightly on the negative side, maybe reading about 4 negative amps.   The voltage read just under 15 volts - say 14.7 the whole time and stays there but within about 3 minutes, the ammeter came back up to zero and stayed there.

   

  I wired the ammeter and external shunt as per Van's Aircraft instructions and my brother Danny (which you've all heard from many times) says there are 2 other ways (according to Dynon) to wire the ammeter which I might do.   

   

  I'm not sure of the best or correct way to wire the ammeter but at  least now I know my alternator is working perfectly and THAT makes me happy.

   

  Maybe I should leave it alone since I now know exactly what it's reading.

   

  Thanks for your input and suggestions.

   

  Matt

   

  



"Robert L. Nuckolls, III" <nuckollsr(at)cox.net> wrote:

  [quote]--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" 



At 09:24 PM 8/27/2007 -0700, you wrote:



 	  Quote: 	
		  Thanks for messages.



Here's the answer to your questions.



I have a Chief Aircraft +/- 40 ammeter with a 40amp shunt.



I think my alternator is 35 amps but can't remember - I'll have to look 

that up. I am running Nav lights, strobe lights, wig wag lights, and a 

full  Garmin stack so I'm thinking I may need to upgrade my 

alternator. Will have to add that up before first flight to see the load.



The ammeter has a positive and negative terminal on the back. The 

positive is connected to to the small screw on the shunt which also has a 

large screw on the same side which is wired directly to the main power bus 

which also splits to a wire between the master and starter relay. The 

negative side on the back of the ammeter is connected to the opposite 

small screw on the shunt which also has a large screw which is wired 

through a 60amp circuit breaker to the main power bus.



Kinda hard to explain without a picture. I followed the Bingeles book 

when I wired it up a few years back so maybe I messed something up.



I do know that the volt meter reads barely under 14 volts with the engine 

running.



Thanks for the  help!!!!


	


The -zero+ reading ammeter is a BATTERY ammeter. When things

are running normally (alternator carrying ship's loads and

battery fully charged) then it SHOULD read at or near zero.

Turn some things on with the engine not running. Let them run

of the battery for 10 minutes or so. The ammeter should be

showing a (-) value - energy is coming out of the battery.

Take a voltmeter reading.



Now, start the engine and turn the alternator on. Note the bus

voltage. We would LIKE to see 14.2 to 14.6 volts but 13.8 or 13.9

would still charge the battery.



After the alternator comes on, if you see a rise in bus voltage,

then the alternator IS working to some degree. Its set point may

be too low . . . but it is working. Now the ammeter should show

a decided (+) reading - energy is being stuffed back into the

battery. Turn all the accessories off and observe the ammeter

which should begin to move back toward zero       Luggage? GPS? Comic books? 

 [quote][b]

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nuckollsr(at)cox.net
Guest

Posted: Mon Sep 03, 2007 4:02 pm Post subject: How to check and alternator??

At 04:30 AM 9/2/2007 -0700, you wrote:



 	  Quote: 	
		  Hi Bob !!

Thanks for the help and suggestions !!  I really appreciate you and all I 

learn from you.



So, I did exactly as you said, and you are 100% correct.   I left on a 

bunch of stuff for about 10 minutes, then started the plane and 

immediately noticed the ammeter was slightly on the negative side, maybe 

reading about 4 negative amps.   The voltage read just under 15 volts - 

say 14.7 the whole time and stays there but within about 3 minutes, the 

ammeter came back up to zero and stayed there.



I wired the ammeter and external shunt as per Van's Aircraft instructions 

and my brother Danny (which you've all heard from many times) says there 

are 2 other ways (according to Dynon) to wire the ammeter which I might do.



I'm not sure of the best or correct way to wire the ammeter but at least 

now I know my alternator is working perfectly and THAT makes me happy.



Maybe I should leave it alone since I now know exactly what it's reading.



Thanks for your input and suggestions.


	


   Sounds like your ammeter is a bit big for the job and

   it may be wired backwards too. Normally, one expects to see

   a STRONG + reading while the battery is being replenished,

   a near ZERO reading while the alternator is carrying ships

   loads and the battery is charged, and a STRONG - reading

   when the alternator is off and everything thing is turned

   on. Your "slightly negative" observation while charging the

   battery tells me it is too small and wired backwards.



   Bob . . .

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