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Where to hook voltage sense wire

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rvg8tor

Joined: 06 Apr 2009
Posts: 50
Location: Olympia, WA

Posted: Sun Mar 06, 2011 11:58 am Post subject: Where to hook voltage sense wire

I have just powered up my panel and I have two EFIS units that talk to each other (Dynon 180 and a 10A),  I was putting the 10A on the EMS page and noticed that the voltage reported on it was 13.4 V and the voltage on the D180 (which is the box with the EMS) was showing 12.8 V.  I have things powered with a power supply putting out 13.8 volts and the battery is out of the loop.  I will have to run down why this is from Dynon but it got me to thinking



Since there is a voltage drop when the power flows from the main bus to the E-Bus through the diode, I wonder where the best place for voltage sensing wire should be, since it will activate on a lower voltage from the main bus.  



Right now I have the Low Voltage light and sense wire on the same breaker on the main bus which gets the highest voltage, the D180 is on the E-bus so its power is going through the E-bus diode.  I am not sure if this is why I see the voltage difference between the two displays, I kind of think not because the 10A when on the EMS page should just be repeating what is on the D180 EMS.



But all this begs the question is there a "Best" location for a standby alternator regulator to monitor the system voltage? Main bus or E-bus?

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_________________
Mike "Nemo" Elliott
RV-8A QB (Engine)
www.mykitlog.com/rvg8tor

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 06, 2011 12:33 pm Post subject: Where to hook voltage sense wire

At 01:58 PM 3/6/2011, you wrote:

 	  Quote: 	
		  



I have just powered up my panel and I have two EFIS units that talk 

to each other (Dynon 180 and a 10A),  I was putting the 10A on the 

EMS page and noticed that the voltage reported on it was 13.4 V and 

the voltage on the D180 (which is the box with the EMS) was showing 

12.8 V.  I have things powered with a power supply putting out 13.8 

volts and the battery is out of the loop.  I will have to run down 

why this is from Dynon but it got me to thinking



Since there is a voltage drop when the power flows from the main bus 

to the E-Bus through the diode, I wonder where the best place for 

voltage sensing wire should be, since it will activate on a lower 

voltage from the main bus.


	


      Can you disable/work-around on the low votlage warning

      for the device powered from the e-bus? Normally, one

      low voltage warning system suffices.

 	  Quote: 	
		  Right now I have the Low Voltage light and sense wire on the same 

breaker on the main bus which gets the highest voltage, the D180 is 

on the E-bus so its power is going through the E-bus diode.  I am 

not sure if this is why I see the voltage difference between the two 

displays, I kind of think not because the 10A when on the EMS page 

should just be repeating what is on the D180 EMS.



But all this begs the question is there a "Best" location for a 

standby alternator regulator to monitor the system voltage? Main bus or E-bus?


	


    Which z-figure are you using? If Z-13/8, the

    rectifier/regulator gets it's voltage sense

    info from the system it's powering. That

    would be true also for any other auxiliary

    engine driven power source.

        Bob . . .

                    ////

                   (o o)

    ===========o00o=(_)=o00o=========

    < Go ahead, make my day . . .   >

    < show me where I'm wrong.      >

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

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user9253

Joined: 28 Mar 2008
Posts: 1927
Location: Riley TWP Michigan

Posted: Mon Mar 07, 2011 7:26 am Post subject: Re: Where to hook voltage sense wire

 	  Quote: 	
		  the 10A when on the EMS page should just be repeating what is on the D180 EMS 	


True if both are powered from the same bus.  But if one EMS gets its power through a diode and the other does not, then they will show different voltages.

Joe

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Joe Gores

rvg8tor

Joined: 06 Apr 2009
Posts: 50
Location: Olympia, WA

Posted: Mon Mar 07, 2011 7:51 am Post subject: Re: Where to hook voltage sense wire

You are correct, my grounds are good but there is a difference in voltage due to the diode the power goes through to get to the E-Bus.  I was surprised to see the difference in that the D10A is and EFIS only unit not and EMS, but through the Dynon DSAB network you can display different items on the D10A screen to include engine instruments.  My surprise was I thought showing this data should just be a repeat of the main EMS information.



My real question here is given that there is a voltage difference between the main bus and the E-bus by about .6 volts which bus would be the best place to have the standby alternator monitor bus voltage.  The standby regulator is set to a lower voltage so if the main alternator is operating fine the standby just stays idle, when the bus it monitors falls below the set point in the standby regulator then it wakes up and starts to provide power.



 	  user9253 wrote: 	
		   	  Quote: 	
		  the 10A when on the EMS page should just be repeating what is on the D180 EMS 	


True if both are powered from the same bus.  But if one EMS gets its power through a diode and the other does not, then they will show different voltages.

Joe

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_________________
Mike "Nemo" Elliott
RV-8A QB (Engine)
www.mykitlog.com/rvg8tor

rvg8tor

Joined: 06 Apr 2009
Posts: 50
Location: Olympia, WA

Posted: Mon Mar 07, 2011 8:06 am Post subject: Re: Where to hook voltage sense wire

 	  nuckolls.bob(at)aeroelect wrote: 	
		  At 01:58 PM 3/6/2011, you wrote:

 	  Quote: 	
		  



I have just powered up my panel and I have two EFIS units that talk 

to each other (Dynon 180 and a 10A),  I was putting the 10A on the 

EMS page and noticed that the voltage reported on it was 13.4 V and 

the voltage on the D180 (which is the box with the EMS) was showing 

12.8 V.  I have things powered with a power supply putting out 13.8 

volts and the battery is out of the loop.  I will have to run down 

why this is from Dynon but it got me to thinking



Since there is a voltage drop when the power flows from the main bus 

to the E-Bus through the diode, I wonder where the best place for 

voltage sensing wire should be, since it will activate on a lower 

voltage from the main bus.



	


      Can you disable/work-around on the low votlage warning

      for the device powered from the e-bus? Normally, one

      low voltage warning system suffices.



Not sure what you meant here but my primary low voltage warning will be the EFIS alarm, since it monitors voltage.



 	  Quote: 	
		  Right now I have the Low Voltage light and sense wire on the same 

breaker on the main bus which gets the highest voltage, the D180 is 

on the E-bus so its power is going through the E-bus diode.  I am 

not sure if this is why I see the voltage difference between the two 

displays, I kind of think not because the 10A when on the EMS page 

should just be repeating what is on the D180 EMS.



But all this begs the question is there a "Best" location for a 

standby alternator regulator to monitor the system voltage? Main bus or E-bus?



	


    Which z-figure are you using? If Z-13/8, the

    rectifier/regulator gets it's voltage sense

    info from the system it's powering. That

    would be true also for any other auxiliary

    engine driven power source.

        Bob . . .

                    ////

                   (o o)

    ===========o00o=(_)=o00o=========

    <Go>

    < show me where I'm wrong.      >

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




My system is Z12 so the standby alternator attaches at the start contactor and then uses the same main bus feed wire.  I have the alternate feed switching for the hot battery bus to the E-bus as a way to isolate the E-bus if I get to a battery only situation.



Since the standby regulator needs to monitor bus voltage I have it set up to monitor the main bus.  As you can see the  low voltage alarm off the EFIS will be different from what the standby regulator reads due to the drop in the diode.  I think I can work around the issue in that the EFIS #2 attached to the main bus has it's own alarms and I can set that to my specifications.

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_________________
Mike "Nemo" Elliott
RV-8A QB (Engine)
www.mykitlog.com/rvg8tor

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Mar 07, 2011 5:03 pm Post subject: Where to hook voltage sense wire

 	  Quote: 	
		  

My system is Z12 so the standby alternator attaches at the start 

contactor and then uses the same main bus feed wire.  I have the 

alternate feed switching for the hot battery bus to the E-bus as a 

way to isolate the E-bus if I get to a battery only situation.


	




 	  Quote: 	
		  Since the standby regulator needs to monitor bus voltage I have it 

set up to monitor the main bus.


	


    Right.



 	  Quote: 	
		     As you can see the  low voltage alarm off the EFIS will be 

 different from what the standby regulator reads due to the drop in 

 the diode.  I think I can work around the issue in that the EFIS #2 

 attached to the main bus has it's own alarms and I can set that to 

 my specifications.


	


    If the alarm for the e-bus instruments can be calibrated,

    then set them for 10.5 volts. That's the voltage your

    battery is 95% used up.



    Gizmos with LV warning attached to the main bus

    get set for 13.5.

   Bob . . .

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