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Question for Bob

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Rocketman1988

Joined: 21 Jun 2012
Posts: 63

Posted: Mon Jul 16, 2018 7:45 am Post subject: Question for Bob

Bob



I am using the Z-14 for a template.



I have looked at the sketch of the aft mounted batteries, as I am building an RV-10 with an electrically dependent engine.



I would like to have the Main and Aux Battery busses located forward instead of aft.  My thought would be to run two large cables from the aft batteries to the forward busses, and small, short wires to the loads.  The sketch you made would require many long small wires and two short large wires.  As an aside, the c/b s would then be located aft, as well.



My question is, would running two large cables forward be viable?



If so, what AWG wire would you recommend? #8, #6, #4 ?  The loads should not exceed 25 -30 A.



Thanks.

Mauledriver(at)nc.rr.com
Guest

Posted: Mon Jul 16, 2018 9:51 am Post subject: Question for Bob

I think you'll find most other Z-14 10's configured the way you are 

describing.Â  Mine certainly is.



On 7/16/2018 11:45 AM, Rocketman1988 wrote:

 	  Quote: 	
		   



 Bob



 I am using the Z-14 for a template.



 I have looked at the sketch of the aft mounted batteries, as I am building an RV-10 with an electrically dependent engine.



 I would like to have the Main and Aux Battery busses located forward instead of aft.  My thought would be to run two large cables from the aft batteries to the forward busses, and small, short wires to the loads.  The sketch you made would require many long small wires and two short large wires.  As an aside, the c/b s would then be located aft, as well.



 My question is, would running two large cables forward be viable?



 If so, what AWG wire would you recommend? #8, #6, #4 ?  The loads should not exceed 25 -30 A.



 Thanks.





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=481658#481658






	




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Rocketman1988

Joined: 21 Jun 2012
Posts: 63

Posted: Mon Jul 16, 2018 10:00 am Post subject: Re: Question for Bob

So what size wire did you run from the aft battery to the forward buss?

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jul 16, 2018 10:59 am Post subject: Question for Bob

Bob



 

 I am using the Z-14 for a template. I have looked at the sketch of the

 aft mounted batteries, as I am building an RV-10 with an electrically

 dependent engine.



 I would like to have the Main and Aux Battery busses located forward instead

 of aft.  My thought would be to run two large cables from the aft batteries

 to the forward busses, and small, short wires to the loads.



    A 'battery bus' is an always hot structure mounted

    close to a battery that drives feeders protected

    by (1) crash-friendly fuses (7A) or breakers (5A)

    -OR- (2) crew-controlled feeders with added relays/

    contactors when 5-7A robustness is insufficient.



    Once separated from the battery, it's some other

    kind of bus . . . you pick the name. Legacy design

    philosophy  calls for a mini-contactor or relay to manage

    the feeder to that bus.  This drives reliability

    of that bus down when the contactor is added.

    Not recommended for powering accessories that

    benefit by getting power from a REAL battery bus.



 The sketch you made would require many long small wires

 and two short large wires.



   How many is 'many'? What are the anticipated feeders?

   What do they power and what are their protection levels?

   

 As an aside, the c/b s would then be located aft, as well.



   Yup, that's how battery busses are . . .  on every airplane

   I've worked with . . .



 My question is, would running two large cables forward be viable?

 If so, what AWG wire would you recommend? #8, #6, #4 ?  The loads should not exceed 25 -30 A.



   This is a departure from legacy design philosophies

   which begs validation with new FMEAs . . . the results

   of which may not be attractive.



 

   Bob . . .

Rocketman1988

Joined: 21 Jun 2012
Posts: 63

Posted: Mon Jul 16, 2018 12:14 pm Post subject: Re: Question for Bob

Bob



Thanks for the insight.



I am using electronic fuel injection and ignition.  So the coil packs, a fuel pump p, and an ECU need to be on a buss powered by both batteries...and the c/b s need to be accessible, i.e. not aft of the baggage compartment.



It appears that I will need to accept the two additional contactors  to feed the forward busses, as the required power will exceed 10 amps...



Would you recommend a continuous duty contactor or a relay between the battery and the load?

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jul 16, 2018 12:30 pm Post subject: Question for Bob

At 03:14 PM 7/16/2018, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "Rocketman1988" <Rocketman(at)etczone.com>



 Bob



 Thanks for the insight.



 I am using electronic fuel injection and ignition.  So the coil packs, a fuel pump p, and an ECU need to be on a buss powered by both batteries...and the c/b s need to be accessible, i.e. not aft of the baggage compartment.



 It appears that I will need to accept the two additional contactors  to feed the forward busses, as the required power will exceed 10 amps...



 Would you recommend a continuous duty contactor or a relay between the battery and the load?



 

 	


   Can you post a sketch of the proposed constellation

   of feeders?



 

 

   Bob . . .

Rocketman1988

Joined: 21 Jun 2012
Posts: 63

Posted: Mon Jul 16, 2018 2:21 pm Post subject: Re: Question for Bob

Bob



This is just a simple drawing with reference to the Z-14.



The feeders to the "hot" busses are the ones in question.  In the RV-10, the 3 contactors are located in the aft fuselage, while I would like the busses to be located forward, with c/b s accessible from the control seat.



Those two wires would each be around 10 feet long...

RV-10 Electrical V1.0.JPG

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ceengland7(at)gmail.com
Guest

Posted: Mon Jul 16, 2018 2:52 pm Post subject: Question for Bob

Just a heads-up, your diode symbols are for zener diodes. I doubt that's what you intend to use, and it could confuse an avionics tech in the future.



On Mon, Jul 16, 2018 at 5:21 PM, Rocketman1988 <Rocketman(at)etczone.com (Rocketman(at)etczone.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "Rocketman1988" <Rocketman(at)etczone.com (Rocketman(at)etczone.com)>

 

 Bob

 

 This is just a simple drawing with reference to the Z-14.

 

 The feeders to the "hot" busses are the ones in question.Â  In the RV-10, the 3 contactors are located in the aft fuselage, while I would like the busses to be located forward, with c/b s accessible from the control seat.

 

 Those two wires would each be around 10 feet long...

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=481674#481674

 

 

 

 

 Attachments: 

 

 http://forums.matronics.com//files/rv_10_electrical_v10_182.jpg

 

	




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Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Mon Jul 16, 2018 3:22 pm Post subject: Question for Bob

As the builder of a -10, with good old 1960 mags and electrical layout, 

I can tell you that you really don't want more battery behind the 

baggage compartment than necessary. You either have a PITA panel to 

remove, or you have to modify the panel to make an access door...and 

most information indicates that panel is structural, so you have to use 

some care in modifying it. If you have a battery of suitable weight in 

the rear to match the original plans, then you could put something light 

weight like an EarthX up on the firewall. It would save you a lot of 

heavy duty cabling.



On 7/16/2018 3:21 PM, Rocketman1988 wrote:

 	  Quote: 	
		   

 

 Bob

 

 This is just a simple drawing with reference to the Z-14.

 

 The feeders to the "hot" busses are the ones in question.  In the RV-10, the 3 contactors are located in the aft fuselage, while I would like the busses to be located forward, with c/b s accessible from the control seat.

 

 Those two wires would each be around 10 feet long...

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=481674#481674

 

 

 

 

 Attachments:

 

 http://forums.matronics.com//files/rv_10_electrical_v10_182.jpg

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

Rocketman1988

Joined: 21 Jun 2012
Posts: 63

Posted: Mon Jul 16, 2018 3:52 pm Post subject: Re: Question for Bob

Sorry about the Zener symbol. The diagram was just sketched out give me something to look at...I never intended on posting it but I did so, as Bob asked...

user9253

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

Posted: Mon Jul 16, 2018 5:57 pm Post subject: Re: Question for Bob

The alternator fuses should be physically located at the other end of the "B" leads near the battery contactors.  The fuses protect the batteries.  The alternator is self current limiting.

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jul 16, 2018 6:00 pm Post subject: Question for Bob

At 05:21 PM 7/16/2018, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "Rocketman1988" <Rocketman(at)etczone.com>



 Bob



 This is just a simple drawing with reference to the Z-14.



 The feeders to the "hot" busses are the ones in question.  In the RV-10, the 3 contactors are located in the aft fuselage, while I would like the busses to be located forward, with c/b s accessible from the control seat.



 Those two wires would each be around 10 feet long... 	


  No, I need to see a schematic of your bus

  structure and a description of what wires

  take power from each bus to its respective

  load.



  This is the information necessary to do FMEA.

  Words may occasionally suffice but a schematic

  is the universal language that offers clarity

  above all words.



 

 

   Bob . . .

Mauledriver(at)nc.rr.com
Guest

Posted: Tue Jul 24, 2018 10:55 am Post subject: Question for Bob

I know the discussion has gone way past this butÂ  I ran 2 AWG between 

the batteries, contactors, and for the forward run to the starter.Â  All 

other 'bus' runs are 8 AWG.



I'll attach a diagram of my Z-14 in my RV10.Â  (2) Odyssey 680s in the 

rear along with the 3 contactors.Â  Everything else on the diagram is 

forward.

On 7/16/2018 2:00 PM, Rocketman1988 wrote:

 	  Quote: 	
		   



 So what size wire did you run from the aft battery to the forward buss?





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=481660#481660






	


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nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jul 24, 2018 4:09 pm Post subject: Question for Bob

At 01:54 PM 7/24/2018, you wrote:

  	  Quote: 	
		  I know the discussion has gone way past this butÂ  I ran 2 AWG between the batteries, contactors, and for the forward run to the starter.Â  All other 'bus' runs are 8 AWG.



 I'll attach a diagram of my Z-14 in my RV10.Â  (2) Odyssey 680s in the rear along with the 3 contactors.Â  Everything else on the diagram is forward.

 	


  That should play as advertised. Only thing

  I would suggest is to make your battery

  jumpers from 4AWG welding cable. Very

  flexible and entirely sufficient

  electrically but MUCH less stress

  on the battery connector screws.



  Do you have a wire runnig from battery(-)

  up to your firewall ground bus?



 

 

   Bob . . .

Mauledriver(at)nc.rr.com
Guest

Posted: Wed Jul 25, 2018 10:07 am Post subject: Question for Bob

On 7/24/2018 8:08 PM, Robert L.       Nuckolls, III wrote:

     

      	  Quote: 	
		                At 01:54 PM 7/24/2018, you wrote:

               	  Quote: 	
		  I know           the discussion has gone           way past this butÂ  I ran 2 AWG between the batteries,           contactors,           and for the forward run to the starter.Â  All other 'bus' runs           are 8           AWG.

           

           I'll attach a diagram of my Z-14 in my RV10.Â  (2) Odyssey           680s in           the rear along with the 3 contactors.Â  Everything else on the           diagram is forward.

         	
       

        That should play as advertised. Only thing

        I would suggest is to make your battery

        jumpers from 4AWG welding cable. Very

        flexible and entirely sufficient

        electrically but MUCH less stress

        on the battery connector screws.

       

        Do you have a wire runnig from battery(-)

        up to your firewall ground bus?

     	
     Yes I do.  My guess is that it is an 8AWG wire running from the     battery to airframe ground connection forward to the ground bus.      That forward ground bus is also grounded to the airframe.

      	  Quote: 	
		  

       

                

             Bob . . .                     	
     



            	 		 			 				 			 		 		 			

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nuckolls.bob(at)aeroelect
Guest

Posted: Wed Jul 25, 2018 11:14 am Post subject: Question for Bob

Do you have a wire running from battery(-)

  up to your firewall ground bus?



 Yes I do.  My guess is that it is an 8AWG wire running from the battery to airframe ground connection forward to the ground bus.  That forward ground bus is also grounded to the airframe.



  Okay . . . the resistance of that wire is probably

  100 times higher than the airframe. The wire doesn't

  hurt anything but it adds no value.



  Also just noticed the dual power source diodes

  for the oil pressure annunciator. The 'thing'

  about Z-14 is that there's virtually zero

  probability that either of the busses will

  go dark. Powering from the aux bus alone

  would eliminate the diodes.



   



 

 

   Bob . . .

GusF16rv8

Joined: 30 May 2018
Posts: 1

Posted: Thu Jul 26, 2018 5:41 am Post subject: Re: Question for Bob

 	  nuckolls.bob(at)aeroelect wrote: 	
		  Do you have a wire running from battery(-) up to your firewall ground bus?



Yes I do.  My guess is that it is an 8AWG wire running from the battery to airframe ground connection forward to the ground bus.  That forward ground bus is also grounded to the airframe.



  Okay . . . the resistance of that wire is probably

  100 times higher than the airframe. The wire doesn't

  hurt anything but it adds no value.



 	




Isn't the point of having a bus or 'field of tabs' grounded directly to the negative batt terminal to prevent ground loops through the airframe?  If so, why then is the wire of no value, because of its length due to being run from the rear?



From the explanation above, it sounds like both ends (batt neg terminal and ground bus) are also grounded to the airframe, is that correct?



Could you specify which wire is 'adds no value' and how the planned system SHOULD be grounded then?  Thanks!

_________________
Gus

RV8 SlowBuild (2006-?)

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