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What Are The Odds?

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s_kilishek(at)yahoo.com
Guest

Posted: Sun Dec 31, 2006 3:10 pm Post subject: What Are The Odds?

Bob:



Thanks for your help.



You're right.  The field supply breaker isn't

tripping, so the OVM-14 apparently isn't getting

involved.



I ran the two tests you suggested: (OAT was 46

degrees, if that means anything).



The voltage between the A/S terminals and the

regulator case varied between 14.7 and 14.9 volts

while the buss voltage moved between 14.7 and 15.2

volts.



Then I installed the test regulator on the back of the

alternator per the picture you posted.  The darn

system ran perfectly!  Bus voltage stayed very steady

between 14.5 and 14.7 volts.



I take this to mean that the regulator and alternator

are fine.  



The fact that the regulator in the system seems to be

trying to regulate at 14.8 volts or so seems wrong,

but I've no hypothesis for that.



The fact that the voltage the regulator sees is a few

tenths of a volt higher than the actual bus voltage

probably indicates a problem with the wiring between

the regulator and the alternator breaker.  This is

about 6 feet of #18 wire from the regulator to the

alternator switch and about 2 feet of #18 wire from

the switch to the breaker (Faston connectors

throughout).



Do you have any suggestions?



Hope you and yours have a happy New Year holiday, and

that 2007 will bring peace, health, happiness and

prosperity for you.



George



---------------------------------------



Time: 09:24:39 PM PST US

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

Subject: Re: What Are The Odds

(snip)

 	  Quote: 	
		  I can't tell whether the regulator is not regulating

or is regulating at >15 volts.


	


   Easy. Use a voltmeter to measure between the A/S

terminals

   and regulator case. THIS is the point where the

regulator

   believes it is seeing bus voltage. You may find

that it

   it sitting happily at 14.2 volts while voltage

   drops in wiring BETWEEN the A/S terminals and the

BUS

   are cause for an artificially raising of regulation

set-point.



   Take one of your regulators and install some short

leads

   on it as illustrated below. Install right on the

back of

   the alternator and see what the bus voltage does

while

   the engine is running and you vary loads by turning

things

   on and off. These experiments totally bypass all

other

   ship's wiring.



http://www.aeroelectric.com/Pictures/Regulators/Alternator_Test_1.jpg



http://www.aeroelectric.com/Pictures/Regulators/Ford_Test_Reg.jpg



   I think you'll find that the alternator and

regulator

   are fine . . . there's some bug in installation.



   Conduct the experiments cited above and report back

the

   results. We can begin to divide the

probabilities-list into

   manageable partitions.



   Bob . . 



__________________________________________________

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nuckollsr(at)cox.net
Guest

Posted: Mon Jan 01, 2007 10:15 am Post subject: What Are The Odds?

At 03:08 PM 12/31/2006 -0800, you wrote:



 	  Quote: 	
		  



Bob:



Thanks for your help.



You're right.  The field supply breaker isn't

tripping, so the OVM-14 apparently isn't getting

involved.



I ran the two tests you suggested: (OAT was 46

degrees, if that means anything).


	


   Not much. I'm not aware of any regulator that

   makes an effort to temperature compensate set-point

   for battery temperature other than those provided

   with remote temperature sensors like the B&C product.



 	  Quote: 	
		  The voltage between the A/S terminals and the

regulator case varied between 14.7 and 14.9 volts

while the buss voltage moved between 14.7 and 15.2

volts.


	


   Hmmm . . . back in the days when I was bolting

   the direct ancestors to those regulators to

   TC aircraft, their set=points were 14.2 +/- 0.2

   volts.



   You're not the first person to report what appears

   to be a steadily climbing set-point value over the

   years. An alternator I repaired off my GMC van a

   few years back was set for 15.2.



   I can only speculate but it seems that the automotive

   side of the house has reasoned that higher set-point

   voltages, while they may sacrifice battery life to some

   degree, the increased voltage produces faster re-charge

   times for pushing energy back into a battery.

 	  Quote: 	
		  Then I installed the test regulator on the back of the

alternator per the picture you posted.  The darn

system ran perfectly!  Bus voltage stayed very steady

between 14.5 and 14.7 volts.



I take this to mean that the regulator and alternator

are fine.


	


   Absolutely. This is but one technique I've used for

   decades in the quest to know what needs replacing and

   why before any hardware is removed from the airplane.

 	  Quote: 	
		  The fact that the regulator in the system seems to be

trying to regulate at 14.8 volts or so seems wrong,

but I've no hypothesis for that.



The fact that the voltage the regulator sees is a few

tenths of a volt higher than the actual bus voltage

probably indicates a problem with the wiring between

the regulator and the alternator breaker.  This is

about 6 feet of #18 wire from the regulator to the

alternator switch and about 2 feet of #18 wire from

the switch to the breaker (Faston connectors

throughout).



Do you have any suggestions?


	


    Keep in mind that "wiring" includes ALL conductor

    pathways including ground. These simple regulators

    use case ground as the negative side sense lead

    for voltage regulation. Just for grins, try running

    your regulator in it's assigned location on the

    airplane but UNBOLTED from ground. Attach a 20AWG

    or so wire to the regulator case ground and

    return it to the battery (-) ground post on the

    firewall . . . do I presume correctly that you have

    installed a single point ground system not unlike

    those illustrated in Z-15?



    See what the dedicated regulator ground does for

    you first.  If things get "better" (the bus now

    settles down to the same regulation set point as

    when the regulator was on the back of the alternator),

    Then let's talk about your ground system structure.

    If it doesn't get better, then bolt back down as

    originally installed and then make a direct, one-wire

    connection between A/S on the regulator and the

    bus. If this settles things down, there's a dynamic

    resistance variability issue or issues with the

    switch and/or breaker. What kind of breaker are

    you using?

 	  Quote: 	
		  Hope you and yours have a happy New Year holiday, and

that 2007 will bring peace, health, happiness and

prosperity for you.


	


    Thank you sir.



    Bob . . .



 	  Quote: 	
		  George



---------------------------------------



Time: 09:24:39 PM PST US

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

Subject: Re: What Are The Odds

(snip)

 >I can't tell whether the regulator is not regulating

 >or is regulating at >15 volts.



    Easy. Use a voltmeter to measure between the A/S

terminals

    and regulator case. THIS is the point where the

regulator

    believes it is seeing bus voltage. You may find

that it

    it sitting happily at 14.2 volts while voltage

    drops in wiring BETWEEN the A/S terminals and the

BUS

    are cause for an artificially raising of regulation

set-point.



    Take one of your regulators and install some short

leads

    on it as illustrated below. Install right on the

back of

    the alternator and see what the bus voltage does

while

    the engine is running and you vary loads by turning

things

    on and off. These experiments totally bypass all

other

    ship's wiring.



http://www.aeroelectric.com/Pictures/Regulators/Alternator_Test_1.jpg



http://www.aeroelectric.com/Pictures/Regulators/Ford_Test_Reg.jpg



    I think you'll find that the alternator and

regulator

    are fine . . . there's some bug in installation.



    Conduct the experiments cited above and report back

the

    results. We can begin to divide the

probabilities-list into

    manageable partitions.



    Bob . .



__________________________________________________

--

2:59 PM



-- incoming mail is certified Virus Free.

Checked by AVG.


	




        Bob . . .

      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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