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Adelk123

Joined: 04 Aug 2018
Posts: 2

Posted: Sat Aug 04, 2018 5:42 pm Post subject: Power

I’ve got a question for the group. I’m currently powering dual board ECU through a DPDT switch with each side of the switch switching different power sources.



I’ve decided I don’t want to use two different power sources for the ECUs. I prefer to just power the ECUs directly off of my engine Bus. This bus is an always hot battery bus mounted at the aft end of the Aircraft. With the floors being closed up, access is challenging but not impossible. I had considered the idea of each ECU having its own circuit powered off of the same bus. I am currently out of additional circuits on that fuse box though. I have considered combining with a circuit that I can readily access. I have two small led baggage lights powered off of that same bus that I could tie in to fairly easily. If there is no real benefit to having two circuits on the same bus due to the switch still being a single point of failure, would it be acceptable to stack the terminals on one side of the switch to power both ECUs from one source? The current for both combined is less than 1/2 of an amp. 



I realize that doing so still creates a single point of failure so I’m looking for advice finding a solution that I might not of already thought of.



Thanks for any advice.

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nuckolls.bob(at)aeroelect
Guest

Posted: Sat Aug 04, 2018 6:02 pm Post subject: Power

This bus is an always hot battery bus mounted at the aft end of the Aircraft. With the floors being closed up, access is challenging but not impossible. I had considered the idea of each ECU having its own circuit powered off of the same bus.



   Depending on how 'orderly' the lay of wires

   is in the bundle carrying the current feeder,

   it may be possible to lap solder TWO wires to

   the end of the single wire thus converting the

   single wire into a 'tag line' for installation

   of a new pair.



 I am currently out of additional circuits on that fuse box though. I have considered combining with a circuit that I can readily access. I have two small led baggage lights powered off of that same bus that I could tie in to fairly easily.



   Use one of those . . . separating them

   eliminates the single point of failure

   for one ECU (or intermediate wiring faults)

   from tripping both systems off line.



  If there is no real benefit to having two circuits on the same bus due to the switch still being a single point of failure, would it be acceptable to stack the terminals on one side of the switch to power both ECUs from one source? The current for both combined is less than 1/2 of an amp.



   Your choice . . . but I couldn't sell that

   idea onto a TC aircraft. I presume you

   currently have a 2nd source on a bus up

   front?  I think I'd leave it there. The

   'plum' in your FMEA pudding is the exceedingly

   remote probability of loosing BOTH sources

   during the consumption of ONE tank of gas.

   Exactly what those sources are is irrelevant

   as long as they too do not suffer a 'cow pie'

   in their FMEA.



   This leaves JUST the switch which, in an

   OBAM aircraft, will see perhaps a couple

   hundred actuations per year . . . at your

   stated load, the electrical life is infinite.

   The mechanical life will be more environmentally

   driven than service driven. I'd just replace

   the switch for grins every 5 years or so . . .



   I've seen more switches (even the $high$ mil-spec

   devices) fail due to chronological AGE in

   a less than pleasant environment than

   from service life . . .



 



 

   Bob . . .

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Adelk123

Joined: 04 Aug 2018
Posts: 2

Posted: Sat Aug 04, 2018 8:10 pm Post subject: Re: Power

Ok, thanks for the feedback.



Yes, I currently have the secondary ECU powered another bus in the front of the airplane.  What I failed to think out completely was the load shedding side of things. My intent was to have the ability to load shed everything except the critical engine items, the second ECU not being critical. The problem is the switchology has become more complex than I like due to the injector relays and their relationship with the ECUs. I feel it’s a safer and a more simplified solution just to have the same power source with both ECUs and leaving no possibility to inadvertently shut down the engine during load shedding.

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Aug 05, 2018 7:33 am Post subject: Power

At 11:10 PM 8/4/2018, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "Adelk123" <andydelk(at)mac.com>



 Ok, thanks for the feedback.



 Yes, I currently have the secondary ECU powered another bus in the front of the airplane.  What I failed to think out completely was the load shedding side of things. My intent was to have the ability to load shed everything except the critical engine items, the second ECU not being critical. The problem is the switchology has become more complex than I like due to the injector relays and their relationship with the ECUs. I feel it’s a safer and a more simplified solution just to have the same power source with both ECUs and leaving no possibility to inadvertently shut down the engine during load shedding.



 	


   Hmmmm . . . perhaps we can help sort the

   sands of your FMEA. Can you describe the

   current architecture . . . or better yet

   . . . post a drawing?  What is your base

   architecture . . . one of the z-figures?

   Have you done a load analysis to define

   your actions upon loss of alternator?



 

 

   Bob . . .

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BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Sun Aug 05, 2018 10:46 am Post subject: Power

Scotty:

"The more they overtake the plumbing the easier it is to stop up the drain."



On Sun, Aug 5, 2018 at 11:38 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:



 	  Quote: 	
		    At 11:10 PM 8/4/2018, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "Adelk123" <andydelk(at)mac.com (andydelk(at)mac.com)>



 Ok, thanks for the feedback.



 Yes, I currently have the secondary ECU powered another bus in the front of the airplane.  What I failed to think out completely was the load shedding side of things. My intent was to have the ability to load shed everything except the critical engine items, the second ECU not being critical. The problem is the switchology has become more complex than I like due to the injector relays and their relationship with the ECUs. I feel itâ€™s a safer and a more simplified solution just to have the same power source with both ECUs and leaving no possibility to inadvertently shut down the engine during load shedding.



 	


   Hmmmm . . . perhaps we can help sort the

   sands of your FMEA. Can you describe the

   current architecture . . . or better yet

   . . . post a drawing?  What is your base

   architecture . . . one of the z-figures?

   Have you done a load analysis to define

   your actions upon loss of alternator?



 

 

   Bob . . .

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yellowduckduo(at)gmail.co
Guest

Posted: Sun Aug 05, 2018 3:03 pm Post subject: Power

15 years ago when I was making similar decisions I picked up a second 

set of injectors and fuel rail from the local auto wrecker and welded 

them in.

It simplified the "switchology" quite a bit.

Both ecu's run all the time and are hard wired to the negative side of 

their dedicated injectors.

Manual toggle switches send positive power to whichever set of injectors 

I wish to operate.

Z-14 allowed independent powering of the two systems without using any 

diodes or relays.

Same thing with the ignitions.

(Now Scotty has to stop up two drains to spoil my day...)

Ken



On 05/08/2018 2:45 PM, FLYaDIVE wrote:

 	  Quote: 	
		   Scotty:



 "The more they overtake the plumbing the easier it is to stop up the 

 drain."



 On Sun, Aug 5, 2018 at 11:38 AM Robert L. Nuckolls, III 

 <nuckolls.bob(at)aeroelectric.com <mailto:nuckolls.bob(at)aeroelectric.com>> 

 wrote:



     At 11:10 PM 8/4/2018, you wrote:

>     

>     <andydelk(at)mac.com <mailto:andydelk(at)mac.com>>

>

>     Ok, thanks for the feedback.

>

>     Yes, I currently have the secondary ECU powered another bus in

>     the front of the airplane.  What I failed to think out completely

>     was the load shedding side of things. My intent was to have the

>     ability to load shed everything except the critical engine items,

>     the second ECU not being critical. The problem is the switchology

>     has become more complex than I like due to the injector relays

>     and their relationship with the ECUs. I feel itâ€™s a safer and a

>     more simplified solution just to have the same power source with

>     both ECUs and leaving no possibility to inadvertently shut down

>     the engine during load shedding.

>



       Hmmmm . . . perhaps we can help sort the

       sands of your FMEA. Can you describe the

       current architecture . . . or better yet

       . . . post a drawing?  What is your base

       architecture . . . one of the z-figures?

       Have you done a load analysis to define

       your actions upon loss of alternator?

       Bob . . .

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Aug 05, 2018 3:54 pm Post subject: Power

 	  Quote: 	
		  I feel it’s a safer and a more simplified solution just to have the same power source with both ECUs and leaving no possibility to inadvertently shut down the engine during load shedding.



 	


   This was a component of the philosophy for the

   E-bus. The idea was to have maximum endurance

   loads on the e-bus and battery bus. If the alternator

   quits you (1) close alternate e-feed, (2) open battery

   master contactor.



   There are no switch ops associated with an appliance

   or system, hence the probability of inadvertently

   shutting down and endurance load was essentially

   zero.



 

 

   Bob . . .

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