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alternator voltage output

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curts63

Joined: 04 Dec 2013
Posts: 30
Location: New Ringgold, PA

Posted: Sat Mar 07, 2015 1:22 pm Post subject: alternator voltage output

My question is this, what is the normal output of the alternator in voltage?  My volt meter is reading up to 14.7 volts when running around 3000rpm.  Is this normal or should it max out around 13.7?



If this is high, I guess I need a new regulator?  My problem is the Garmin system seems to fluctuate as the voltage gets up to 14.5 or more volts.  When you pull back the throttle and let the voltage drop, things settle down.



Thanks,

Curt

nuckollsr

Joined: 24 Mar 2009
Posts: 95
Location: Medicine Lodge, KS

Posted: Sat Mar 07, 2015 2:42 pm Post subject: alternator voltage output

At 15:22 2015-03-07, you wrote:

 	  Quote: 	
		  



My question is this, what is the normal output of the alternator in 

voltage?  My volt meter is reading up to 14.7 volts when running 

around 3000rpm.  Is this normal or should it max out around 13.7?


	


    13.8 is the MINIMUM needed to fully

    charge a lead-acid battery . . . but it

    takes a LONG time to top off. Starting

    batteries in vehicles are generally recharged

    at 14.2 plus/minus 0.2 and 14.7 is not

    too high.



 	  Quote: 	
		  If this is high, I guess I need a new regulator?  My problem is the 

Garmin system seems to fluctuate as the voltage gets up to 14.5 or 

more volts.  When you pull back the throttle and let the voltage 

drop, things settle down.


	


    Is this a piece of aircraft hardware?

    The voltage level you cite should be

    no problem. What system are we talking

    about?



Bob . . .

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

Bob Nuckolls

AeroElectric Connection

P.O. Box 130

Medicine Lodge, KS  67104-0130

Mobile: 316-209-7528

Web: http://aeroelectric.com

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

curts63

Joined: 04 Dec 2013
Posts: 30
Location: New Ringgold, PA

Posted: Sun Mar 08, 2015 3:31 am Post subject: Re: alternator voltage output

My system is the Garmin G3X touch.  The engine is the Jabiru 3300, using the Kubota regulator.  Most times when I take off, the voltage is around 12.5, and shortly after at full power it will climb to the 14.7 range.  It's at that time, the tachometer starts acting erratically.



If I pull the power back and the voltage drops a little, the tach will settle to a smoother reading.

BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Sun Mar 08, 2015 8:06 pm Post subject: alternator voltage output

Curt:

The required output of the alternator & ACU to charge a battery is:  13.8 to 14.2 VDC at Minimum of 4 Amps.  If you are not seeing that voltage rand you are compromising your system and not charging the battery correctly of fully.

Barry

On Sun, Mar 8, 2015 at 7:31 AM, curts63 <curts63(at)verizon.net (curts63(at)verizon.net)> wrote:

[quote]--> JabiruEngine-List message posted by: "curts63" <curts63(at)verizon.net (curts63(at)verizon.net)>

 

 My system is the Garmin G3X touch.  The engine is the Jabiru 3300, using the Kubota regulator.  Most times when I take off, the voltage is around 12.5, and shortly after at full power it will climb to the 14.7 range.  It's at that time, the tachometer starts acting erratically.

 

 If I pull the power back and the voltage drops a little, the tach will settle to a smoother reading.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=439146#439146

 

 

 

 

 

 

 

 ===========

 ne-List" target="_blank">http://www.matronics.com/Navigator?JabiruEngine-List

 ===========

 ">http://forums.matronics.com

 ===========

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

 ===========

 

 

 

 [b]

BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Sun Mar 08, 2015 8:14 pm Post subject: alternator voltage output

Curt:

What do you mean by "fluctuating"?  

Garmin equipment is designed to run up to 36 VDC,so your slightly high reading of 14.7 VDC is really not an issue for the equipment.  It is slightly high for charging but still ... acceptable.... Your reading makes me question what you are using for a VOM?  The accuracy!

Next...  Back to the "fluctuating"...  With the numbers you are posting I'm thinking the problem is more in-line with the wiring.

Barry





On Sat, Mar 7, 2015 at 4:22 PM, curts63 <curts63(at)verizon.net (curts63(at)verizon.net)> wrote:

[quote]--> JabiruEngine-List message posted by: "curts63" <curts63(at)verizon.net (curts63(at)verizon.net)>

 

 My question is this, what is the normal output of the alternator in voltage?  My volt meter is reading up to 14.7 volts when running around 3000rpm.  Is this normal or should it max out around 13.7?

 

 If this is high, I guess I need a new regulator?  My problem is the Garmin system seems to fluctuate as the voltage gets up to 14.5 or more volts.  When you pull back the throttle and let the voltage drop, things settle down.

 

 Thanks,

 Curt

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=439131#439131

 

 

 

 

 

 

 

 ===========

 ne-List" target="_blank">http://www.matronics.com/Navigator?JabiruEngine-List

 ===========

 ">http://forums.matronics.com

 ===========

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

 ===========

 

 

 

 [b]

curts63

Joined: 04 Dec 2013
Posts: 30
Location: New Ringgold, PA

Posted: Mon Mar 09, 2015 3:33 am Post subject: Re: alternator voltage output

the fluctuating of the tach is something like this.  When I take off the tach is around 2650 rpm and fairly steady.  After starting to climb out, the tach shows anywhere from 330 rpm to 3300 rpm, or the display will "red flag" the instrument.  The rpm will vary in those ranges.  Yesterday, it happened on the ground.



The wiring for the tach hookup is a single shielded wire from the alternator output to the Garmin GEA-24 box.  In the setup for the system, you select "jabiru alternator" as the choice for input.  I thought it seemed pretty simple, but has proven to be elusive.



I have no idea why this is occurring.  So far, we can't recreate the issue consistently to pin point a common cause.  My limited experience and knowledge has me looking on these sites for assistance.  My "avionics" guy that did almost all of the wiring is at a loss.

nuckollsr

Joined: 24 Mar 2009
Posts: 95
Location: Medicine Lodge, KS

Posted: Mon Mar 09, 2015 3:47 am Post subject: alternator voltage output

At 06:31 2015-03-08, you wrote:

 	  Quote: 	
		  



My system is the Garmin G3X touch.  The engine is the Jabiru 3300, 

using the Kubota regulator.  Most times when I take off, the voltage 

is around 12.5, and shortly after at full power it will climb to the 

14.7 range.  It's at that time, the tachometer starts acting erratically.



If I pull the power back and the voltage drops a little, the tach 

will settle to a smoother reading.




	


   Okay, this sounds more like a signal/noise issue than a

   voltage issue. 14.7 is not all that much out

   of whack . . . and certainly not high enough to

   push any piece of avionics into the weeds.



   How does the Garmin get RPM information from

   the engine?





Bob . . .

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

Bob Nuckolls

AeroElectric Connection

P.O. Box 130

Medicine Lodge, KS  67104-0130

Mobile: 316-209-7528

Web: http://aeroelectric.com

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

BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Mon Mar 09, 2015 5:44 am Post subject: alternator voltage output

Curt:

If what you are saying is correct?  You just answered your own question.

1 - 

On Mon, Mar 9, 2015 at 7:33 AM, curts63 <curts63(at)verizon.net (curts63(at)verizon.net)> wrote:

[quote]--> JabiruEngine-List message posted by: "curts63" <curts63(at)verizon.net (curts63(at)verizon.net)>

 

 the fluctuating of the tach is something like this.  When I take off the tach is around 2650 rpm and fairly steady.  After starting to climb out, the tach shows anywhere from 330 rpm to 3300 rpm, or the display will "red flag" the instrument.  The rpm will vary in those ranges.  Yesterday, it happened on the ground.

 

 The wiring for the tach hookup is a single shielded wire from the alternator output to the Garmin GEA-24 box.  In the setup for the system, you select "jabiru alternator" as the choice for input.  I thought it seemed pretty simple, but has proven to be elusive.

 

 I have no idea why this is occurring.  So far, we can't recreate the issue consistently to pin point a common cause.  My limited experience and knowledge has me looking on these sites for assistance.  My "avionics" guy that did almost all of the wiring is at a loss.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=439189#439189

 

 

 

 

 

 

 

 ===========

 ne-List" target="_blank">http://www.matronics.com/Navigator?JabiruEngine-List

 ===========

 ">http://forums.matronics.com

 ===========

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

 ===========

 

 

 

 [b]

BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Mon Mar 09, 2015 5:59 am Post subject: alternator voltage output

Curt:

IF what you are saying is correct?  You just answered your own question.

1 - You do NOT run any instruments directly off the alternator!  Got that???

2 - From the alternator you go to the ACU (Alternator Control Unit) - (Voltage Regulator).

3 - From the alternator you go to the BATTERY.  <-- This is the heavy wire used to charge the battery.  The battery has to be charged and the battery also acts as a stabilizing device.  It smooths out the high and low outputs from the alternator.   The ACU is what stabilizes the voltage to the Buss.<-- Simple explanation.

4 - From the BATTERY you go to the plane's BUSS.  

5 - >From the plane's BUSS you go to a Circuit Breaker (CB) and then to your instruments.

6 - IF you are seeing all sorts of fluctuations I'm betting it is because you have the instrument connected directly to the Alternator as you stated.

Once you verify your answer or correct your plane's wiring to the above.  THEN we can look at things like:

Wire Size

Wire Type - Shielded?

How you Grounded the shielded and where?

How you ran the wire.

NOW!  The question I have to ask about the RPM:

You saw the fluctuations of the RPM on the tack.  BUT!  Did you hear and feel the fluctuations? Is this an electrical issue you are chasing, or is it mechanical?

Barry



On Mon, Mar 9, 2015 at 7:46 AM, Robert L Nuckolls III <bob.nuckolls(at)aeroelectric.com (bob.nuckolls(at)aeroelectric.com)> wrote:

[quote]--> JabiruEngine-List message posted by: Robert L Nuckolls III <bob.nuckolls(at)aeroelectric.com (bob.nuckolls(at)aeroelectric.com)>

 

 At 06:31 2015-03-08, you wrote:

  	  Quote: 	
		   --> JabiruEngine-List message posted by: "curts63" <curts63(at)verizon.net (curts63(at)verizon.net)>

 

 My system is the Garmin G3X touch.  The engine is the Jabiru 3300, using the Kubota regulator.  Most times when I take off, the voltage is around 12.5, and shortly after at full power it will climb to the 14.7 range.  It's at that time, the tachometer starts acting erratically.

 

 If I pull the power back and the voltage drops a little, the tach will settle to a smoother reading.

 

 	
 

   Okay, this sounds more like a signal/noise issue than a

   voltage issue. 14.7 is not all that much out

   of whack . . . and certainly not high enough to

   push any piece of avionics into the weeds.

 

   How does the Garmin get RPM information from

   the engine?

 

 

 

 

 Bob . . .

 

 

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

 Bob Nuckolls

 AeroElectric Connection

 P.O. Box 130

 Medicine Lodge, KS  67104-0130

 Mobile: [url=tel:316-209-7528]316-209-7528[/url]

 Web: http://aeroelectric.com

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

 

 ====================================

 ne-List" target="_blank">http://www.matronics.com/Navigator?JabiruEngine-List

 ====================================

 ">http://forums.matronics.com

 ====================================

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

 ====================================

 

 

 

 



[b]

nuckollsr

Joined: 24 Mar 2009
Posts: 95
Location: Medicine Lodge, KS

Posted: Mon Mar 09, 2015 6:55 am Post subject: alternator voltage output

the fluctuating of the tach is something like this.  When I take off the tach is around 2650 rpm and fairly steady.  After starting to climb out, the tach shows anywhere from 330 rpm to 3300 rpm, or the display will "red flag" the instrument.  The rpm will vary in those ranges.  Yesterday, it happened on the ground.



 The wiring for the tach hookup is a single shielded wire from the alternator output to the Garmin GEA-24 box.  In the setup for the system, you select "jabiru alternator" as the choice for input.  I thought it seemed pretty simple, but has proven to be elusive.



 I have no idea why this is occurring.  So far, we can't recreate the issue consistently to pin point a common cause.  My limited experience and knowledge has me looking on these sites for assistance.  My "avionics" guy that did almost all of the wiring is at a loss.



 

    It's a fairly common practice to deduce engine RPMs

    by sampling the frequency of the AC voltage produced

    by the permanent magnet alternator. If there were

    nothing else attached to the alternator's stator winding,

    the output would be a clean sine wave signal. Pretty

    easy to 'decode' for its information about frequency.

    As soon as you hook a rectifier/regulator to the alternator,

    there's a host of noises that get impressed on these

    wires that make the voltage anything BUT a clean

    sine wave. There's a certain amount of signal conditioning

    needed to reject the trash leaving the tachometer

    circuits with clean data.



    I'm betting that your particular configuration

    presents a noise signature at the ragged edge of

    Garmin's design considerations. At the higher

    RPMs there are artifacts of rectifier/regulator

    switching noises that are confusing the tachometer.



    According to my copy of a g3x installation manual,

    the Jabiru signal is known to be 6 pulses per rev

    off the alternator winding. So 2400 RPM x 6 is

    14,400 pulses per minute or 240Hz. A relatively

    easy experiment to conduct is to fabricate a 

    filter like this . . .



 [img]cid:.0[/img]

   This filter has a frequency roll-off in the neighborhood

   of 240Hz and would be a strong attenuator of

   artifacts of higher frequency.  



   You can solder all the parts together and

   cover with a piece of heat-shrink. You would

   have three leads coming out, AC Input, Signal

   Output and Ground. This network would go a long

   way toward limiting the high frequency noises

   that I think are confusing the G3x.



 



 

 Bob . . . 



 

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

 Bob Nuckolls

 AeroElectric Connection

 P.O. Box 130

 Medicine Lodge, KS  67104-0130

 Mobile: 316-209-7528

 Web:  http://aeroelectric.com

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

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nuckollsr

Joined: 24 Mar 2009
Posts: 95
Location: Medicine Lodge, KS

Posted: Mon Mar 09, 2015 9:23 am Post subject: alternator voltage output

OOPS!!!! Got my tongue wrapped around my eyeteeth and 

    couldn't see what I was drawing . . . There was an

    error in the first drawing that would have resulted in

    a really poor performing filter.  Drawing corrected

    below . . .

 [img]cid:7.1.0.9.0.20150309122111.01c08da8(at)aeroelectric.com.1[/img] 



 



 

 

 Bob . . . 



 

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

 Bob Nuckolls

 AeroElectric Connection

 P.O. Box 130

 Medicine Lodge, KS  67104-0130

 Mobile: 316-209-7528

 Web:  http://aeroelectric.com

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

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nuckollsr

Joined: 24 Mar 2009
Posts: 95
Location: Medicine Lodge, KS

Posted: Mon Mar 09, 2015 11:13 am Post subject: alternator voltage output

At 13:04 2015-03-09, you wrote:

 	  Quote: 	
		  The Jabiru alternator coil floats with respect to the electric 

ground. The signal relies on parasitic capacitance and whatever 

leaks inside the regulator. You'll get a much steadier signal if you 

also tie a 10K 1/2W resistor between ground and the alternator wire 

that you didn't use for the G3x input.



I had poor indication on a UMA tach, solved it using the resistor 

above but found it interfered with the 'low charge' output from the 

regulator. The final fix for me was to use an audio transformer as a balun.



Rob


	


   That's another good approach. Yes, the AC power

   coil is 'floating' but when connected to the

   rectifier/regulator, either side of the ac winding

   is either a volt or so above ground (- half cycle)

   to many volts above ground (+ half cycle) . . . and

   the wave form is really ratty . . .



   Going across the AC winding with the isolation

   transformer gets around the wave form distortion

   generated by the R/R.

Bob . . .

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

Bob Nuckolls

AeroElectric Connection

P.O. Box 130

Medicine Lodge, KS  67104-0130

Mobile: 316-209-7528

Web: http://aeroelectric.com

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

curts63

Joined: 04 Dec 2013
Posts: 30
Location: New Ringgold, PA

Posted: Mon Mar 09, 2015 11:17 am Post subject: Re: alternator voltage output

Bob, 

Thank you for the information and sketch.  I'll give this to my avionics guy tonight and see if we can get the parts.  I'll let you know if this works.



Thanks again,

Curt

nuckollsr

Joined: 24 Mar 2009
Posts: 95
Location: Medicine Lodge, KS

Posted: Mon Mar 09, 2015 6:46 pm Post subject: alternator voltage output

At 14:18 2015-03-09, you wrote:

 	  Quote: 	
		  



Bob,

Thank you for the information and sketch.  I'll give this to my 

avionics guy tonight and see if we can get the parts.  I'll let you 

know if this works.



Thanks again,

Curt


	




 	  Quote: 	
		    Got bins full of parts. Can drop a suite

   of parts in an envelope if you need them.
	


   Also, that transformer coupled approach

   has a high order probability of success

   as well.



   I would modify it a bit to utilize readily

   available transformers  . . . but if plan-A

   doesn't get it, plan-B is a good bet.



   Bottom line is that I've never met a noise

   problem that couldn't be whipped.





Bob . . .

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

Bob Nuckolls

AeroElectric Connection

P.O. Box 130

Medicine Lodge, KS  67104-0130

Mobile: 316-209-7528

Web: http://aeroelectric.com

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

curts63

Joined: 04 Dec 2013
Posts: 30
Location: New Ringgold, PA

Posted: Sun Mar 29, 2015 4:55 am Post subject: Re: alternator voltage output

First, thank you for the input and problem solving.  I wanted to let you know that the "filter" that you suggested did a rock solid job from 0-3000 rpm.  When I'm at full throttle, I still get a fluctuating tach, but at least now it doesn't flag.



Thanks,

Curt

nuckollsr

Joined: 24 Mar 2009
Posts: 95
Location: Medicine Lodge, KS

Posted: Sun Mar 29, 2015 10:47 am Post subject: alternator voltage output

At 07:55 2015-03-29, you wrote:

  	  Quote: 	
		  --> JabiruEngine-List message posted by: "curts63" <curts63(at)verizon.net>



 First, thank you for the input and problem solving.  I wanted to let you know that the "filter" that you suggested did a rock solid job from 0-3000 rpm.  When I'm at full throttle, I still get a fluctuating tach, but at least now it doesn't flag. 	


   Oh man . . . I think I was supposed to send

   you some parts for that . . . I think I dropped

   the ball.



   Okay, my next best guess is that the signal is

   still too big. Try removing one of the series

   zeners . . . trimming it down to this:



 

 [img]cid:7.1.0.9.0.20150329133937.010c0048(at)aeroelectric.com.0[/img] 



  	  Quote: 	
		   	


 If that's still short of rock solid stable, try

 adding more 0.1 uF caps in parallel across the

 signal line.



 Sorry 'bout that kit.



 

 

 Bob . . . 



 

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

 Bob Nuckolls

 AeroElectric Connection

 P.O. Box 130

 Medicine Lodge, KS  67104-0130

 Mobile: 316-209-7528

 Web:  http://aeroelectric.com

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

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curts63

Joined: 04 Dec 2013
Posts: 30
Location: New Ringgold, PA

Posted: Mon Mar 30, 2015 3:24 am Post subject: Re: alternator voltage output

No problem.  I'd rather have your expertise than the parts.  I'll have him make another filter without the extra diode and see what happens.  Thank you again.



curt

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