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Braided ground strap to battery?

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crabandy(at)yahoo.com
Guest

Posted: Tue Mar 05, 2013 8:18 am Post subject: Braided ground strap to battery?

Might be a stupid question but, I was wondering about the possibility of using a braided ground strap from b and c to go from the battery to the grounding forest of tabs on the firewall. 

Thanks 

Andy

Sent from my iPhone

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JOHN TIPTON

Joined: 17 Sep 2006
Posts: 239
Location: Torquay - England

Posted: Tue Mar 05, 2013 8:32 am Post subject: Braided ground strap to battery?

So long as it cannot touch any live (plus volts) contacts - OK, I would think



John



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On 5 Mar 2013, at 16:16, Andy <crabandy(at)yahoo.com> wrote:



 	  Quote: 	
		   

 

 

 Might be a stupid question but, I was wondering about the possibility of using a braided ground strap from b and c to go from the battery to the grounding forest of tabs on the firewall. 

 Thanks 

 Andy

 Sent from my iPhone

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FisherPaulA(at)johndeere.
Guest

Posted: Tue Mar 05, 2013 8:50 am Post subject: Braided ground strap to battery?

That's what I did.  Actually I did three straps:

	- Engine to Battery ground

	- Engine to forest of tabs on firewall

	- Battery ground to forest of tabs on firewall



So far, no problems in 3.5 years.  It's probably more than is really required, but I already had the extra strap and I didn't figure it would hurt.  Belt and suspenders I guess...



Paul A. Fisher

RV-7A N18PF

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mrspudandcompany(at)veriz
Guest

Posted: Tue Mar 05, 2013 9:51 am Post subject: Braided ground strap to battery?

 	  Quote: 	
		   That's what I did.  Actually I did three straps:

 - Engine to Battery ground

 - Engine to forest of tabs on firewall

 - Battery ground to forest of tabs on firewall


	




        With multiple ground paths to the battery, 

        from the above configuration, isn't there a 

        chance of introducing ground loops, 

        causing noise problems??



        Roger



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FisherPaulA(at)johndeere.
Guest

Posted: Tue Mar 05, 2013 10:56 am Post subject: Braided ground strap to battery?

Good question.  My thought was that the systems that would be susceptible to noise (all of the audio components) are inside the cabin - nothing forward of the firewall.  So for those components there is only one path to the battery.  Only the starter and the alternator would have dual paths.  Obviously the starter is only used once per flight, so it's not a problem, so that just leaves the alternator.  I can't explain the physics of WHY it's not a problem.  I can only state that the fact that there ARE no problems!  YMMV.



 - Paul



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nuckolls.bob(at)aeroelect
Guest

Posted: Tue Mar 05, 2013 11:18 am Post subject: Braided ground strap to battery?

At 10:16 AM 3/5/2013, you wrote:

 	  Quote: 	
		  

Might be a stupid question but, I was wondering about the 

possibility of using a braided ground strap from b and c to go from 

the battery to the grounding forest of tabs on the firewall.


	




   The legacy rationale for ground straps of many

   finely drawn wires was common in vehicles for

   grounding an engine to the vehicle frame or maintaining

   electrical continuity across moveable joints in

   the machine. The  engine needed to move around in

   its mounts but often needed grounding integrity

   for starter motors and generators/alternators.

   Electrical connections that are in motion with

   respect to each other demand a conductor that

   is exceedingly resistant to flex failure (See

   explanation of design goals for 19+strand wire

   on airplanes in the 'Connection).



   How long a strap are we talking about? Have

   you considered welding cable for BOTH battery

   (-) and (+) connections?  It's a good thing to

   reduce the bending moments on battery terminals

   due to stiff wire. Some builders have experienced

   battery post failures when short lengths of 2AWG

   'aircraft' wire was used to jumper a battery(+)

   to the contactor.



   I would recommend that you consider 4AWG welding

   cable jumpers for both battery connections. Then

   consider what materials make the most sense for

   cost, weight, system performance, or wire that your

   hangar mate donated to the project.



   A braided strap from fire wall ground to crankcase

   is a good thing. A welding cable jumper is equally

   good. I'm aware of no particular advantage for

   using a fabricated braid-strap to make connections

   to the battery . . . but it wouldn't hurt anything

   either.

   Bob . . .

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crabandy(at)yahoo.com
Guest

Posted: Tue Mar 05, 2013 2:52 pm Post subject: Braided ground strap to battery?

Thanks for the replies!

 I can make the 2 AWG (what I currently have in my shop) work but the service loop is kinda big. I was thinking about having the ground strap made (about 6 inches) by BandC and for the same price as the welding cable I think the strap would fit nicer. 

 



    

From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>

To: aeroelectric-list(at)matronics.com 

Sent: Tuesday, March 5, 2013 1:18 PM

Subject: Re: Braided ground strap to battery?

--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>



At 10:16  AM 3/5/2013, you wrote:

 	  Quote: 	
		   --> AeroElectric-List message posted by: Andy <crabandy(at)yahoo.com (crabandy(at)yahoo.com)>

 

 

 Might be a stupid question but, I was wondering about the possibility of using a braided ground strap from b and c to go from the battery to the grounding forest of tabs on the firewall.


	




  The legacy rationale for ground straps of many

  finely drawn wires was common in vehicles for

  grounding an engine to the vehicle frame or maintaining

  electrical continuity across moveable joints in

  the machine. The  engine needed to move around in

  its mounts but often needed grounding integrity

  for starter motors and generators/alternators.

  Electrical connections that are in motion with

  respect to each other demand a conductor that

  is exceedingly  resistant to flex failure (See

  explanation of design goals for 19+strand wire

  on airplanes in the 'Connection).



  How long a strap are we talking about? Have

  you considered welding cable for BOTH battery

  (-) and (+) connections?  It's a good thing to

  reduce the bending moments on battery terminals

  due to stiff wire. Some builders have experienced

  battery post failures when short lengths of 2AWG

  'aircraft' wire was used to jumper a battery(+)

  to the contactor.



  I would recommend that you consider 4AWG welding

  cable jumpers for both battery connections. Then

  consider what materials make the most sense for

  cost, weight, system performance, or wire that your

  hangar mate donated to the project.



  A braided strap from fire wall ground to crankcase

  is a good thing. A welding cable  jumper is equally

  good. I'm aware of no particular advantage for

  using a fabricated braid-strap to make connections

  to the battery . . . but it wouldn't hurt anything

  either.



 [quote][b]

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