Wire size & Battery Ground postion

[sonny junell]

I know this has been answered before; but just can't find it in archive. So if you know exactly where this post is, please provide the link.

RV-10 w/60 amp alternator,

Can i simply ground to fusalge on (-) side of battery? Or do i need to run the ground to panle & Engine like ol knuckles(sp)says to do.

I was going to use a 4awg wire.

As far as running this wire to my (Main power bus)? Have other used a terminal block ? i.e my single 4awg wire to terminal block then on to starter?

If none of this makes sense, its because I don't know what the h*** I am doing any way Thanks

 

[rleffler]

RV-10 w/60 amp alternator, Can i simply ground to fusalge on (-) side of battery? Or do i need to run the ground to panle & Engine like ol knuckles(sp)says to do. I was going to use a 4awg wire.

You can, but I believe most run the ground wire to the firewall. I'm using a #2 welding cable, although a #4 should be fine for most. It should be the same as the positive power cable.

As far as running this wire to my (Main power bus)? Have other used a terminal block ? i.e my single 4awg wire to terminal block then on to starter?

Are you talking about the ground or power?

Most folks use a ground block on the firewall, sometimes called a forest of tabs that looks like the following picture. You can get this at B&C or SteinAir.

If you are talking about power, what does your schematic require? While you can use a terminal strip, I don't know anyone that has done that. You need to ensure that it can handle 60a.

I ran the power to a passthrough connector on the firewall, then on to the starter and to my VP-200. You can get these from Bluesea.

If none of this makes sense, its because I don't know what the h*** I am doing any way Thanks

Several things that helped me with my electrical design are:

1. Put your entire schematic on paper or you favorite CAD program
2. Do a second revision of your schematic, but instead of an electrical focus, layout a physical design. This will cause you to think about cable runs, and placement of devices. In a RV-10 devices that are directly connected on the schematic, may be located at different ends of the aircraft.
3. While some may consider this to be over the top, document a wirebook. I used excel to document each wire in the aircraft, with the color, guage, what is connected at each end, and the labels for each end. This will make installation go much quicker and troubleshooting easier. You can sort this list by each end of wire (i.e. a specific connector) and it will help when you are building your wire harness. Assuming that you're building your own.
4. Then share these with trusted friends for a peer review. If you have really thick skin, post links here for peer review with the masses.

While planning is painfull for most, the old adage of spending 80% of your time planning and 20% implementation will make things go much easier.

 

[RV10Rob]

I grounded mine next to the battery with a #2 cable, just like the Van's wiring harness plan shows.

-Rob

 

[RV10inOz]

I did not want to run a ground through the aircraft frame like that, so we ran 35mm2 SDI which is Single flex Double Insulated all the way to the engine frame.

Then a smaller ground to the instruments and body.

No earthing problems for the engine nor with radio's etc.

 

[aturner]

Can i simply ground to fusalge on (-) side of battery? Or do i need to run the ground to panle & Engine like ol knuckles(sp)says to do.

If none of this makes sense, its because I don't know what the h*** I am doing any way Thanks

Actually, Bob Nuckolls offers a more nuanced view:

http://aeroelectric.com/articles/Battery_Grounds/Battery_Grounds.html

Nuckolls is a great source of information for folks like us.

Matronics aeroelectric board: http://forums.matronics.com/viewforum.php?f=3

Bob's Book: https://matronics.com/aeroelectric/Catalog/AECcatalog.html

Bob's website: http://www.matronics.com/aeroelectric/

 

[aerhed]

I grounded mine next to the battery with a #2 cable, just like the Van's wiring harness plan shows.

Me Too. Much like virtually every 12V, neg grd, metal vehicle ever produced.

 

[sonny junell]

Thanks

Rleffler and all

Thank you very much. The diagram and pictures were very helpful. I never could read books without pictures

I supposed many of my questions would have been answered had vans sent me the electrical section. Maybe they did and I didn't see em.

#2 wire and ground the battery on the mounting plate. I will be visiting B&C after this post, next time I drive by Joe Pool Marina I will pick up one of those thur post for the firewall that looks like a great way to carry power to my main bus

Thanks again

 

[RudiGreyling]

How About best of both methods? or worse?

Standard Rear Earthing

AND

Grounding Block on both sides of Firewall.

PLUS

I am thinking to ground it at the Back of the Battery, but run a thinner wire from that same point to the front of the firewall that will cater for 60A my altenator can deliver, then use those grounding blocks to create an earthing point for everthing there on the Firewall, forward for engine and rear for avionics.

I am thinking then to Earth the engine on that same grounding block via a thick earth strap. It will ensure the sensative engine probes all got the same earth as the avionics.

The only potensial problem I see is during actual engine cranking, hopefully all those huge amps will find its way back via the parralel Airframe circuit instead of my thin 60AMP parralel ground wire?

OK what's wrong with my logic.

Thanks in advance
Rudi

 

[rleffler]

Standard The only potensial problem I see is during actual engine cranking, hopefully all those huge amps will find its way back via the parralel Airframe circuit instead of my thin 60AMP parralel ground wire?

If you run a ground wire, it needs to be the same guage as the power wire.

Remember, electrons are going to take the path of least resistance. While I don't have any imperical data, I suspect the direct ground wire will have less resistance than the airframe.

 

[RudiGreyling]

If you run a ground wire, it needs to be the same guage as the power wire.

Remember, electrons are going to take the path of least resistance. While I don't have any imperical data, I suspect the direct ground wire will have less resistance than the airframe.

Thanks BOB! Yeay i know path of least resistance, but how much in real practise is it going to matter Copper cable vs Airframe in parralell...I guess if you have a bad earth everything is gonna go down the little earth wire.

I am trying to find a middle ground for a good forward earth instead of running another huge fat heavy wire to the front.

I am kindow happy that the starting current flows back via the airframe, but not the sensors and avionics, I want them on the same point and earthing, anyone can help?

 

[rleffler]

Thanks BOB! Yeay i know path of least resistance, but how much in real practise is it going to matter Copper cable vs Airframe in parralell...I guess if you have a bad earth everything is gonna go down the little earth wire.

I am trying to find a middle ground for a good forward earth instead of running another huge fat heavy wire to the front.

I am kindow happy that the starting current flows back via the airframe, but not the sensors and avionics, I want them on the same point and earthing, anyone can help?

I'm using the forest of tabs approach on the firewall for all the avionics. As you know, these are the most sensitive to grounding issues and it eliminates ground loop issues.

I am running a #2 ground to the back, but I will admit it's redundant and not required. What haven't decided is whether or not to ground the batteries at their mount point, or just ground via the #2 to the firewall. I don't think there is a right answer. Both approaches work.

 

[aerhed]

If you frame ground and run a ground wire forward, won't it create a ground loop?