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Electrical system planning

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Jump4way

Joined: 18 May 2015
Posts: 14

Posted: Wed Jun 03, 2015 5:56 pm Post subject: Electrical system planning

I'm at the early stages of planning my electrical system. I've got the Aeroelectric connection book and am studying the diagrams to see which would fit my admittedly rough plan.



I'm strongly considering the EFII electronic fuel and ignition system. Obviously the electrical system design would be paramount to the success of this system. What is the opinion of the group on the best design idea to follow? The z13-8 with the sd-8 alternator and a single battery? The z19 with dual battery and electronic ignition, or just throw my hands up in the air and pick up the bus manager system that EFII sells?



I'm leaning toward the z13-8 but I've got a question on what would happen if a battery were to short internally. Would the alternator or backup alternator continue to supply power to the busses to power the engine electronics?



Like I said, early stages here. Any advice is very welcomed.

bob.verwey(at)gmail.com
Guest

Posted: Wed Jun 03, 2015 9:15 pm Post subject: Electrical system planning

As always KISS rules!

Think very carefully about your mission.....

On 4 June 2015 at 03:56, Jump4way <andydelk(at)gmail.com (andydelk(at)gmail.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "Jump4way" <andydelk(at)gmail.com (andydelk(at)gmail.com)>

 

 I'm at the early stages of planning my electrical system. I've got the Aeroelectric connection book and am studying the diagrams to see which would fit my admittedly rough plan.

 

 I'm strongly considering the EFII electronic fuel and ignition system. Obviously the electrical system design would be paramount to the success of this system. What is the opinion of the group on the best design idea to follow? The z13-8 with the sd-8 alternator and a single battery? The z19 with dual battery and electronic ignition, or just throw my hands up in the air and pick up the bus manager system that EFII sells?

 

 I'm leaning toward the z13-8 but I've got a question on what would happen if a battery were to short internally. Would the alternator or backup alternator continue to supply power to the busses to power the engine electronics?

 

 Like I said, early stages here. Any advice is very welcomed.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=442966#442966

 

 

 

 

 

 

 

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           -Matt Dralle, List Admin.

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-- 

Best...Bob Verwey



 

  [quote][b]

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Thu Jun 04, 2015 5:06 am Post subject: Re: Electrical system planning

It is VERY unusual for a battery to short internally, especially a modern AGM type.  There was one recent accident attributed to a shorted battery.

  Read this thread: http://tinyurl.com/FEW-P51 The type of battery in this incident is not known.  Having two batteries wired per Z-19 (assumed) did not keep the engine running

  I think that it is more likely that a propeller will break or a wing will fall off than for an AGM battery to short out.  But if it is a concern, then two contactors can be used, one for the battery and one for the alternator (s).  I agree with you that Z13-8 is a good choice.  The SD-8 should be able to keep the engine running without a battery if need be.

Joe

_________________
Joe Gores

Jump4way

Joined: 18 May 2015
Posts: 14

Posted: Thu Jun 04, 2015 6:31 am Post subject: Re: Electrical system planning

Thanks for the replies. I'm  definitely concerned about deviating from the KISS method.



It would be interesting to know more about the exact cause of that electrical system failure in the link provided. Bob answered one of my questions in the link provided about what happens when a battery has an internal short.



I have a separate question about grounding. I know it's recommended to have a single point grounding system located usually at the firewall. In the RV-8 I'm building the battery is mounted aft for cg purposes and I have chosen to ground the battery locally to the fuselage with the intent of having a forest of tabs at the firewall which the engine would ground to the hot side of the firewall and the avionics and various other grounds would ground to on the cold side. My question is would this be considered adequate? The EFII manual says all grounds should go back to the battery negative terminal which goes against what I have up to now.



Thoughts?

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Thu Jun 04, 2015 9:28 am Post subject: Re: Electrical system planning

I think that your plan will work OK.  Bob's Z figures have some grounding diagrams.  Audio systems are vulnerable to grounding errors.  The headset jacks should not be grounded to the airframe.  Instead, separate ground wires should run back to the radio or intercom.

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Jun 04, 2015 1:49 pm Post subject: Electrical system planning

At 09:31 AM 6/4/2015, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "Jump4way" <andydelk(at)gmail.com>



 Thanks for the replies. I'm  definitely concerned about deviating from the KISS method.



 It would be interesting to know more about the exact cause of that electrical system failure in the link provided. Bob answered one of my questions in the link provided about what happens when a battery has an internal short.



 I have a separate question about grounding. I know it's recommended to have a single point grounding system located usually at the firewall. In the RV-8 I'm building the battery is mounted aft for cg purposes and I have chosen to ground the battery locally to the fuselage with the intent of having a forest of tabs at the firewall which the engine would ground to the hot side of the firewall and the avionics and various other grounds would ground to on the cold side. My question is would this be considered adequate? 	




    The central point ground on the firewall is

    the process and technology of choice IRRESPECTIVE

    of where your ground your battery.



    See   http://tinyurl.com/n9rgrg8



    Ground all but panel mounted stuff on the

    firewall including EFII stuff. Craft an

    auxiliary ground bus for the panel mounted

    goodies. See figure Z-15, View =A=



 



 



 

   Bob . . .    [quote][b]

Jump4way

Joined: 18 May 2015
Posts: 14

Posted: Thu Jun 04, 2015 3:33 pm Post subject: Re: Electrical system planning

Thanks for the reply. It seems from the picture you linked that it is acceptable to ground the battery locally. The z-15 seems to show that it is best to ground the battery at the firewall ground. Yet again, I'm confused, is my local battery ground acceptable?



For the avionics ground bus, should that be isolated from the airframe then tied to the firewall ground or can I just mount another forest of tabs behind the panel direct to the airframe for avionics grounds then tie that one to the firewall?

Jump4way

Joined: 18 May 2015
Posts: 14

Posted: Thu Jun 04, 2015 3:36 pm Post subject: Re: Electrical system planning

Thanks for the reply. It seems from the picture you linked that it is acceptable to ground the battery locally. From what I understand you to say, is acceptable. The z-15 seems to show that it is best to ground the battery at the firewall ground. Yet again, I'm confused, is my local battery ground acceptable?



For the avionics ground bus, should that be isolated from the airframe then tied to the firewall ground or can I just mount another forest of tabs behind the panel direct to the airframe for avionics grounds then tie that one to the firewall? It seems to me that it should be isolated from the airframe in some manner.

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Jun 04, 2015 4:32 pm Post subject: Electrical system planning

At 06:33 PM 6/4/2015, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "Jump4way" <andydelk(at)gmail.com>



 Thanks for the reply. It seems from the picture you linked that it is acceptable to ground the battery locally. The z-15 seems to show that it is best to ground the battery at the firewall ground. Yet again, I'm confused, is my local battery ground acceptable? 	


    It is not preferable . . . but since tens of

    thousands of airplanes have performed successfully

    with rear-mounted, airframe grounded batteries,

    it's an acceptable alternative.



    



  	  Quote: 	
		  For the avionics ground bus, should that be isolated from the airframe then tied to the firewall ground or can I just mount another forest of tabs behind the panel direct to the airframe for avionics grounds then tie that one to the firewall? 	


   "Avionics grounds" are that plethora of

   wires that bring power and shield grounds

   together . . . ideally in as close proximity

   to that collection of appliances as practical.



   A forest of tabs is exceedingly bulky for

   this application. Better to fabricate something

   like this



  http://aeroelectric.com/Pictures/Grounding/AGB_V.jpg



   Much more compact and installer friendly

  



 

   Bob . . .    [quote][b]

Jump4way

Joined: 18 May 2015
Posts: 14

Posted: Mon Jun 08, 2015 9:57 am Post subject: Re: Electrical system planning

Thanks for the advice. I'm moving ahead with the Z-13/8 architecture as described by Bob in his book.



I do have a question regarding the feeder line from the battery contactor to the main battery buss as well as the feeder to the E-bus. In the RV-8 I'm building, I have the battery mounted aft. I currently have my main power bus, diode, ebus, and one main battery buss mounted forward of the panel with the battery, battery contactor, and one  6 slot battery buss fuse panel mounted near the battery in the aft portion of the fuselage.



 What I would like to do is tie the forward battery buss fuse panel (8 slots) to the aft battery buss fuse panel to accomodate shorter wire runs for the various devices to be connected. The z-13/8 diagram calls for wire runs of less than 6 inches from the battery contactor to the battery buss as well as from the main battery bus to the ebus relay. Is there a way to safely do what I would like or should I just get a larger main battery buss fuse panel and mount it aft then run each of the devices all the way to the back of the fuselage?

ceengland7(at)gmail.com
Guest

Posted: Mon Jun 08, 2015 10:01 am Post subject: Electrical system planning

On June 8, 2015 12:36:38 PM CDT, Ross Home <rossmickey(at)comcast.net> wrote:[quote] [quote]--> AeroElectric-List message posted by: "Ross Home" <rossmickey(at)comcast.net>I can't comment on the battery shorting internally other than it is anextremely rare occurrence especially if you follow Bob's advice of replacingyour battery on a regular basis.Here is what Bob's says in his latest version of the book."If I were building an airplane today, my ship would be fitted with FigureZ-13/8 electrical system with an 18 AH battery and dual Emagair ignitionsystems. I can deduce no other configuration that delivers more value."Ross--

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