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Battery Cables

PostPosted: Mon Jan 14, 2008 4:17 pm
by deshaffer
The aircraft being discussed is a Just Aircraft, model Escapade, with a Rotax 912 ULS engine.

I have located the battery behind the luggage aft wall per the factory instructions.


1.  What AWG size battery cable should be used?
2.  Should I run the negative cable from the battery to engine ground point?  Or ground the frame locally?
3.  Currently, I am using number 6 AWG battery cable wire.


PostPosted: Mon Jan 14, 2008 8:07 pm
by rgmullins
Welcome to the group!!!

I am also using  6 AWG cable. I grounded to the frame back by the battery. I figured why add the extra weight?


PostPosted: Tue Jan 15, 2008 1:13 pm
by scubarider
I just ran both of my wires to the front and tied in most of my grounding to one point on the frame.  Probably didn't need to do that but didn't know any better.  :?  

PostPosted: Tue Jan 15, 2008 2:23 pm
by rgmullins
John sent me a private email (not sure why it was private...) but he said Just Air had told him he needed to run 2 separate cables and they had to be 4 AWG. What have others ran for the 912?

PostPosted: Tue Jan 15, 2008 4:26 pm
by b1x4nqb
I know for that Dave ran 1 and used the frame as a ground source.  Not sure on his gauge.  I just picked up some 2 gauge locally at an auto parts store.  I wasn't looking for that thick of stuff but I had a hard time finding it locally.  With shipping costs I figured my price couldn't be beat.  The weight is a little more but then again, if I skip a lunch I could easily offset the difference.  

Paul, PA

PostPosted: Tue Jan 15, 2008 5:12 pm
by DaveU
I used 4 ga welding cable, it has a flexible copper core.  I ran a positive wire from the battery to the master relay, right by the battery, and then on to the firewall for the starting selenoid.  I grounded the battery to the fuselage on the tab closest to the battery that the rear baggage panel mounts to.  The then used the center motor mount lug (not used for the mount when the little wheel is in the back) to connect to the ground lug on the starter.  

Cubs have been wired in this manner since the 30's.  I do not have any problems with this method.  I checked it at the annual and there is no issue with corrosion.


Battery cables

PostPosted: Tue Jan 15, 2008 11:48 pm
by KevinC
Troy recommended that I run two from the battery to the firewall - so that is what I did.  Dave is probably right, though - electrically speaking.



Battery Cables

PostPosted: Wed Jan 16, 2008 6:11 pm
by John S
Thanks for all your replies, guys.  Kevin, what AWG size cables are you running?  As I understand it from your posting, you'll be running a positive and a negative cable from the battery up to a grounding point on the firewall.

Also, should all my grounds come to that same point on the firewall?

Thanks again for all your help.  This is a great forum.

John S.

rgmullins:  I was too new to the list to understand how to make a reply.  The private reply was all I could find, so I went for it.  I think I've got the regular system figured out now.  Thanks for your help.