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EFIS Power Switch

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art(at)zemon.name
Guest

Posted: Sun Aug 21, 2016 12:08 pm Post subject: EFIS Power Switch

Folks,



I am reviewing my wiring diagrams, prior to starting to assemble the wiring harness for my EFIS. I started with MGL's installation instructions, which include an On/Off power switch for the whole MGL system: display + iBox + RDAC + magnetometer + AHRS. You can see the "EFIS On-Off" switch in these three diagrams:

â€‹

Â can bus 1.pdf

â€‹â€‹

Â can bus 2.pdf

â€‹â€‹

Â ibox.pdf

â€‹



I am honestly not sure that I want this switch. Is there ever a time when I would have the master switch on but not want power to the EFIS?

As far as current draining the battery, I am not too worried. The whole system (all five components) draws just 1.7-2.9 amps, depending on display brightness and whether or not the heaters in the magnetometer and AHRS are energized.

Â  Â  -- Art Z.



-- 

http://CheerfulCurmudgeon.com/"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel

user9253

Joined: 28 Mar 2008
Posts: 1926
Location: Riley TWP Michigan

Posted: Sun Aug 21, 2016 6:27 pm Post subject: Re: EFIS Power Switch

 	  Quote: 	
		  I am honestly not sure that I want this switch. Is there ever a time when I would have the master switch on but not want power to the EFIS? 	


The pilot should have the ability to shut off each and every electrical load.  If the MGL units have their own switches, than an additional switch is not necessary.  If the MGL malfunctions or gives off smoke, there should be a way to shut it off without shutting off everything else.

  On the other hand, if you do not mind shutting off the master switch if necessary, it is not a big deal.  Builders of experimental aircraft can wire the airplane to meet their goals.  As long as it is not dangerous, do it the way you want.

_________________
Joe Gores

art(at)zemon.name
Guest

Posted: Mon Aug 22, 2016 6:47 am Post subject: EFIS Power Switch

Joe,



The conversation about measuring oil pressure at engine start is what got me pondering the question: Is there ever a time when I would have the master switch on but not want power to the EFIS?

I am guessing that, should we actually think about and debate it, we may decide that the statement "the pilot should have the ability to shut off each and every electrical load" may prove an oversimplification, left over from olden days of yore. Thus my question and I am hoping for more responses.

Â  Â  -- Art Z.



On Sun, Aug 21, 2016 at 9:27 PM, user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:

 	  Quote: 	
		  > I am honestly not sure that I want this switch. Is there ever a time when I would have the master switch on but not want power to the EFIS?

 

 The pilot should have the ability to shut off each and every electrical load. Â  	


-- 

http://CheerfulCurmudgeon.com/"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel

rene(at)felker.com
Guest

Posted: Mon Aug 22, 2016 7:14 am Post subject: EFIS Power Switch

I use my EIS to monitor the engine at startup.Â  I do not turn on the EFIS until after engine start.

 

Between breakers and switches I can effectively turn off everythingâ€¦â€¦.

 

Rene'

801-721-6080

 

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

Sent: Monday, August 22, 2016 8:44 AM

To: aeroelectric-list(at)matronics.com

Subject: Re: Re: EFIS Power Switch



 

Joe,

 



The conversation about measuring oil pressure at engine start is what got me pondering the question: Is there ever a time when I would have the master switch on but not want power to the EFIS?



 



I am guessing that, should we actually think about and debate it, we may decide that the statement "the pilot should have the ability to shut off each and every electrical load" may prove an oversimplification, left over from olden days of yore. Thus my question and I am hoping for more responses.



 



    -- Art Z.

 

On Sun, Aug 21, 2016 at 9:27 PM, user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:

 	  Quote: 	
		   I am honestly not sure that I want this switch. Is there ever a time when I would have the master switch on but not want power to the EFIS?


	


The pilot should have the ability to shut off each and every electrical load.  

 



-- 

http://CheerfulCurmudgeon.com/



"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel

billhuntersemail(at)gmail
Guest

Posted: Mon Aug 22, 2016 7:27 am Post subject: EFIS Power Switch

Dynon can (and should) be on during engine start. . It has a soft key "button" you can press to shut it down (not electrically isolated).  

If some of the magic smoke starts to escape then the CB can be used to isolate it from its electrical source.  

Bill Hunter  

On Aug 22, 2016 7:57 AM, "Art Zemon" <art(at)zemon.name (art(at)zemon.name)> wrote: 	  Quote: 	
		  Joe,



The conversation about measuring oil pressure at engine start is what got me pondering the question: Is there ever a time when I would have the master switch on but not want power to the EFIS?

I am guessing that, should we actually think about and debate it, we may decide that the statement "the pilot should have the ability to shut off each and every electrical load" may prove an oversimplification, left over from olden days of yore. Thus my question and I am hoping for more responses.

Â  Â  -- Art Z.



On Sun, Aug 21, 2016 at 9:27 PM, user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:

 	  Quote: 	
		  > I am honestly not sure that I want this switch. Is there ever a time when I would have the master switch on but not want power to the EFIS?

 

 The pilot should have the ability to shut off each and every electrical load. Â  	


-- 

http://CheerfulCurmudgeon.com/"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel

Mauledriver(at)nc.rr.com
Guest

Posted: Mon Aug 22, 2016 7:45 am Post subject: EFIS Power Switch

This a question I pondered, decided on a course and have now flown it 

for 5 years.  I went with (3) GRT/HX EFIS units and left them 

unswitched.  My thinking was I wanted them on, I never wanted them 

inadvertently switched off (due to boot time), and I didn't want to add 

another potential point of failure.



In retrospect, a switch for each unit would have been welcomed. The (3) 

units along with the rest of my avionics puts enough of a drain on the 

system that (1) 680 is not enough to prevent brownouts during starts.  

More importantly I like to run my panel with the engine off for flight 

plan loading and clearances.  But I knew all that up front during the 

planning process so I went with Bob's dual batt, dual alt setup.  And 

this 'almost' works for me. That is, if everything is 100%, I can run 

the panel for extended periods if desired, start the engine, etc without 

a concern. But....



If anything is less than 100%, I got  brownouts during start-up. Why 

would things be less than 100% in an airworthy plane?  Stuff happens - 

e.g. the 24/7 clock in the GRTs used to run the battery down until GRT 

killed the function in a later release.  One side of the charging system 

was undercharging a battery, etc.



I could have installed switches to help manage things when desired but 

instead I doubled down and added  TCW's power stabilizer (not a battery 

but a big condenser I think).  This provided the extra 'load smoothing' 

to avoid any and all brownouts during starts, that is, in my particular 

situation/configuration.  Given its ongoing success, I still really like 

not having them switched, probably because that's what I have.  But 

switches are probably a simpler and certainly more cost effective 

solution to a perhaps non-existent problem.



(note: all my operations are for travel, most flights IFR, >50% of 

operations are not at home airport, YMMV)



Bill "happily flying around with the entire kitchen sink for a panel" Watson

 	  Quote: 	
		   â€‹

 I am honestly not sure that I want this switch. Is there ever a time 

 when I would have the master switch on but not want power to the EFIS?



 As far as current draining the battery, I am not too worried. The 

 whole system (all five components) draws just 1.7-2.9 amps, depending 

 on display brightness and whether or not the heaters in the 

 magnetometer and AHRS are energized.




	




---

This email has been checked for viruses by Avast antivirus software.

https://www.avast.com/antivirus

cluros(at)gmail.com
Guest

Posted: Mon Aug 22, 2016 8:30 am Post subject: EFIS Power Switch

"The pilot should have a way of shutting off each and every electrical load"

Without turning off the master switch, I cannot shut off:

Fuel quantity gauges,

Any engine gauges,

Voltmeter and ammeter,

Intercom,

USB power.

If one of these items fails in spectacular fashion without blowing the fuse, I guess I'll have to turn the master off but I'm not sure that's a likely failure mode. I don't think I have ever flown an aircraft that has a switch for every electrical load. 



Sebastien



On Aug 22, 2016, at 07:44, Art Zemon <art(at)zemon.name (art(at)zemon.name)> wrote:

 	  Quote: 	
		  Joe,



The conversation about measuring oil pressure at engine start is what got me pondering the question: Is there ever a time when I would have the master switch on but not want power to the EFIS?

I am guessing that, should we actually think about and debate it, we may decide that the statement "the pilot should have the ability to shut off each and every electrical load" may prove an oversimplification, left over from olden days of yore. Thus my question and I am hoping for more responses.

    -- Art Z.



On Sun, Aug 21, 2016 at 9:27 PM, user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:

 	  Quote: 	
		  > I am honestly not sure that I want this switch. Is there ever a time when I would have the master switch on but not want power to the EFIS?

 

 The pilot should have the ability to shut off each and every electrical load.  	


-- 

http://CheerfulCurmudgeon.com/"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Aug 22, 2016 9:11 am Post subject: EFIS Power Switch

At 09:44 AM 8/22/2016, you wrote:

  	  Quote: 	
		  Joe,



 The conversation about measuring oil pressure at engine start is what got me pondering the question: Is there ever a time when I would have the master switch on but not want power to the EFIS? 	


  Battery only ground ops for maintenance.

  



 

  	  Quote: 	
		  I am guessing that, should we actually think about and debate it, we may decide that the statement "the pilot should have the ability to shut off each and every electrical load" may prove an oversimplification, left over from olden days of yore. Thus my question and I am hoping for more responses. 	


  In 'heavy iron', virtually everything

  in the cockpit is powered through a breaker

  that is accessible to the crew.



  Generally speaking, there are few if

  any panel mounted items capable of generating

  hazardous amounts of smoke. Things inside

  panel mounted electro-whizzies tend to simply burn

  through in a few seconds without flaming or

  propagating the failure . . . all inside

  some sort of enclosure.



  By the time you sense the smoke, identify

  its source, find the breaker/switch and do

  something about it, it's all over.



  I cannot imagine any failure scenario

  in a thoughtfully designed architecture

  that gives one pause for concerns about

  absolute and immediate control over power

  on the panel.



  The highest risk failures are for hard

  faults on wires. They have range of distance

  and penetration along with proximity

  to other potential victims.  This is what

  fuses and breaker are for. Beyond that,

  the risks are vanishingly small.



 



 

   Bob . . .

art(at)zemon.name
Guest

Posted: Mon Aug 22, 2016 10:02 am Post subject: EFIS Power Switch

On Mon, Aug 22, 2016 at 12:10 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 	  Quote: 	
		    At 09:44 AM 8/22/2016, you wrote:

  	  Quote: 	
		  Joe,



 The conversation about measuring oil pressure at engine start is what got me pondering the question: Is there ever a time when I would have the master switch on but not want power to the EFIS? 	


 Â Battery only ground ops for maintenance.

	


That makes sense. A transponder check, for instance. So in my plane, if I skip the EFIS power switch, I would have an unwanted load on the battery of 1.2-2.9 amps.

Thanks for all of the comments, people. You have given me food for thought.

Â  Â  -- Art Z.

-- 

http://CheerfulCurmudgeon.com/"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Aug 22, 2016 11:19 am Post subject: EFIS Power Switch

At 01:01 PM 8/22/2016, you wrote:

  	  Quote: 	
		  On Mon, Aug 22, 2016 at 12:10 PM, Robert L. Nuckolls, III < nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

   At 09:44 AM 8/22/2016, you wrote:

  	  Quote: 	
		   Joe,



  The conversation about measuring oil pressure at engine start is what got me pondering the question: Is there ever a time when I would have the master switch on but not want power to the EFIS? 	


  Â Battery only ground ops for maintenance.



  That makes sense. A transponder check, for instance. So in my plane, if I skip the EFIS power switch, I would have an unwanted load on the battery of 1.2-2.9 amps. 	


   Perhaps I should have been more detailed.



   EXTENDED ground ops . . . for the time that

   it takes to run an occasional test, you're

   not likely to seriously tax the battery . . .

   but then we all KNOW how long our battery

   will run ENDURANCE loads . . . right?



   For extended ground ops, an ac mains

   ground power supply becomes cheaper

   every year. A few years ago I sold a

   switch mode ground power supply good for

   22A (as I recall) for about $125.



   Nowadays, one can purchase a 15v, 27A

   supply for $32 delivered to your door.



  http://tinyurl.com/zwmvcpp



   Put a heat-sinked diode in series with

   the supply to prevent inadvertent back-feed

   and this critter will probably run everything

   you need to run . . . even pitot heat.



   A switch (or switches) installed for the

   purpose of managing battery drain in

   ground ops may not be so practical.



  



 

   Bob . . .

art(at)zemon.name
Guest

Posted: Mon Aug 22, 2016 1:23 pm Post subject: EFIS Power Switch

Whoa. The electronics do keep getting cheaper and cheaper. I still have an old 12V power supply kicking around in my basement. I bought it in the early 1970s and used it for running mobile CB equipment at home, back in the days when you could actually have a real conversation on a CB radio. If I remember correctly, I paid upwards of $100 for a 100W power supply. What an investment!



Â  Â  -- Art Z.





On Mon, Aug 22, 2016 at 2:18 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 	  Quote: 	
		    At 01:01 PM 8/22/2016, you wrote:

  	  Quote: 	
		  On Mon, Aug 22, 2016 at 12:10 PM, Robert L. Nuckolls, III < nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 	
  At 09:44 AM 8/22/2016, you wrote:

  	  Quote: 	
		   Joe,



  The conversation about measuring oil pressure at engine start is what got me pondering the question: Is there ever a time when I would have the master switch on but not want power to the EFIS? 	


  Ã‚ Battery only ground ops for maintenance.



  That makes sense. A transponder check, for instance. So in my plane, if I skip the EFIS power switch, I would have an unwanted load on the battery of 1.2-2.9 amps.

 Â  Perhaps I should have been more detailed.



 Â  EXTENDED ground ops . . . for the time that

 Â  it takes to run an occasional test, you're

 Â  not likely to seriously tax the battery . . .

 Â  but then we all KNOW how long our battery

 Â  will run ENDURANCE loads . . . right?



 Â  For extended ground ops, an ac mains

 Â  ground power supply becomes cheaper

 Â  every year. A few years ago I sold a

 Â  switch mode ground power supply good for

 Â  22A (as I recall) for about $125.



 Â  Nowadays, one can purchase a 15v, 27A

 Â  supply for $32 delivered to your door.



  http://tinyurl.com/zwmvcpp



 Â  Put a heat-sinked diode in series with

 Â  the supply to prevent inadvertent back-feed

 Â  and this critter will probably run everything

 Â  you need to run . . . even pitot heat.



 Â  A switch (or switches) installed for the

 Â  purpose of managing battery drain in

 Â  ground ops may not be so practical.



 Â 



 

 Â  Bob . . .  

	




-- 

http://CheerfulCurmudgeon.com/"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel

user9253

Joined: 28 Mar 2008
Posts: 1926
Location: Riley TWP Michigan

Posted: Mon Aug 22, 2016 2:21 pm Post subject: Re: EFIS Power Switch

A pullable circuit breaker or fuse gives the pilot the ability to shut off a load.  If a breaker is used that can not be tripped by the pilot, then I would consider adding a switch.

_________________
Joe Gores

peter(at)sportingaero.com
Guest

Posted: Mon Aug 22, 2016 11:52 pm Post subject: EFIS Power Switch

When maintaining your airplane it is sometimes convenient to not have the EFIS, or other similar systems, operating. A pull able breaker can be useful in this case.Â  It would also provide emergency isolation if required when flying. Peter 

On 22 Aug 2016 5:07 p.m., "Bill Watson" <Mauledriver(at)nc.rr.com (Mauledriver(at)nc.rr.com)> wrote: 	  Quote: 	
		  --> AeroElectric-List message posted by: Bill Watson <Mauledriver(at)nc.rr.com (Mauledriver(at)nc.rr.com)>

 

 This a question I pondered, decided on a course and have now flown it for 5 years.Â  I went with (3) GRT/HX EFIS units and left them unswitched.Â  My thinking was I wanted them on, I never wanted them inadvertently switched off (due to boot time), and I didn't want to add another potential point of failure.

 

 In retrospect, a switch for each unit would have been welcomed. The (3) units along with the rest of my avionics puts enough of a drain on the system that (1) 680 is not enough to prevent brownouts during starts.Â  More importantly I like to run my panel with the engine off for flight plan loading and clearances.Â  But I knew all that up front during the planning process so I went with Bob's dual batt, dual alt setup.Â  And this 'almost' works for me. That is, if everything is 100%, I can run the panel for extended periods if desired, start the engine, etc without a concern. But....

 

 If anything is less than 100%, I gotÂ  brownouts during start-up. Why would things be less than 100% in an airworthy plane?Â  Stuff happens - e.g. the 24/7 clock in the GRTs used to run the battery down until GRT killed the function in a later release.Â  One side of the charging system was undercharging a battery, etc.

 

 I could have installed switches to help manage things when desired but instead I doubled down and addedÂ  TCW's power stabilizer (not a battery but a big condenser I think).Â  This provided the extra 'load smoothing' to avoid any and all brownouts during starts, that is, in my particular situation/configuration.Â  Given its ongoing success, I still really like not having them switched, probably because that's what I have.Â  But switches are probably a simpler and certainly more cost effective solution to a perhaps non-existent problem.

 

 (note: all my operations are for travel, most flights IFR, >50% of operations are not at home airport, YMMV)

 

 Bill "happily flying around with the entire kitchen sink for a panel" Watson

  	  Quote: 	
		   â€‹

 I am honestly not sure that I want this switch. Is there ever a time when I would have the master switch on but not want power to the EFIS?

 

 As far as current draining the battery, I am not too worried. The whole system (all five components) draws just 1.7-2.9 amps, depending on display brightness and whether or not the heaters in the magnetometer and AHRS are energized.

 

 	
 

 

 ---

 This email has been checked for viruses by Avast antivirus software.

 https://www.avast.com/antivirus

 

 

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