Two lugs on Batt contactor

[RVG8tor]

I have the battery just aft of the firewall and the master contactor is there, a short run of #4 wire goes forward of the firewall to the start contactor. I need to run the main bus feed wire off the master contactor as well but the post does not seem long enough. The photo shows just the fat wire going to the starter with a lock washer.

The lug I need to add is for a #6 wire, so how do I get this done. The nut that is up against the contactor housing is fat, I could put a smaller nut there but not sure if that would mess up stuff inside. My other thought is to get some copper bar stick (.125) and put 3 holes in it, the middle hole goes on the contactor post and the other two connect the start relay feed and the main bus feed. I would have to find some way to cover the center post, boots would cover the other connections.

So how have you other solved the issue. I could run my main bus feed off the batter side of the start contactor but would like to use just one fat wire thought the firewall, seems smart to use the fat wire from the battery to the start relay for a dual purpose. The other option is to take the lock nut out of the equation, but that does not seem smart, maybe a star washer would make it all fit

Thanks for any help

 

[aerhed]

You can change the inside nut. Just don't let the post/stud turn. Hold the tip with pliers or something when you tighten/loosen the nut.

 

[RVG8tor]

Whats the deal

over a hundred looks and one reply. How did you guys flying get tow lugs on one post of the battery relay?

Hoping for some ideas soon!

 

[Ironflight]

over a hundred looks and one reply. How did you guys flying get tow lugs on one post of the battery relay?

I honestly don't remember.... How's that for an answer?

Will have to look in to my photo archives.

 

[Bill Wightman]

A few ideas

Mike, I think you're gonna have to thread that fat nut off to expose enough of the threaded post for your two lugs. I personally have not tried it, but as "aerhed" said, it looks like it should come off. Just make sure the post doesn't rotate when you back the nut off.

As an alternative, you could eliminate the split ring washer and use a low profile self locking nut instead. Then you'd have enough length for the two terminals.

Finally, you could use a coupling nut on top of the first terminal, then bolt into the coupler to capture the second terminal.

Coupling Nut

I personally do not like the idea of the copper bar with the two holes in it. The less "exposure" the high-amperage components & wiring have to the airframe, the better. Keep it simple, strong, neat and secure.

Hope my rambling helped...

 

[Walt]

Install a new Solenoid

I use a Cole Hersee 24143 and have plenty of stud length for 2 copper bus bars. Yours does look a little short.

http://www.colehersee.com/pdf/master_cat/e_solenoid.PDF

 

[Bob'sRV6A]

I googled up "battery double lug"

and got a pretty interesting site:
http://www.electerm.com/battery.html#2pole
I don't have much time right now to explore further.

They have some double crimp stud connectors below the crimping tools. Might be what you are looking for.
I'm just at that point of trying to figure out my electrical system and I was wondering about just how to handle your situation. In fact the latest notion was a Z13 and it has 3 conductors off the contactor.
It would be great if you kept us informed on how you worked this out. It seems to be a big hole in the data bank.
Bob

 

[RVG8tor]

Problem solved

Thanks for the inputs but while you guys answered my plea for help I tried a novel idea, see how it fits first. Well I can't use the lock washer that came with the relay but a star washer should work. I got the idea looking at relays B&C sells, they supply a star washer instead of a lock washer.

I still need to get the star washer but this is the fit without the washer, I think with the washer it will just give me a couple thread.

BTW, I had an old relay from a Cessna I owned many years ago and I took the inner nut off, the post is finished like a carriage bolt, it sit in a square opening, so if the relay Van's sent has the same design there is not danger of turning the post provided you keep it snug to the square opening.

Again, thank sorry for my impatiences I just gotta get this baby done!

 

[jmjula]

I am using MS21042 self locking nuts, as can be seen on right side of the master contactor here: http://jmjula.home.comcast.net/~jmjula/images/electrical/batt_contactors.jpg

 

[elippse]

It actually takes just a very small turn on the lug to have the contact washer inside the contactor not to meet the lug flat but just contact it on an edge. When it does that for a while it will get hot and not make good contact. Even though the cutout looks square, the little bit of slop that's there will allow a slight angular mis-alignment.

 

[scsmith]

My vote

I would vote for either a star washer or a lock nut like the MS21042. I would not risk removing the inner nut, for the reason Elippse said. The contactor may work for a while, but may fail prematurely if you disturb the alignment.