F

Flying Scotsman

Well Known Member
OK, based on inputs from my fellow builders in SoCal and some posts on this site, I'm switching from "regular" wires to welding cable for the starter and the alternator runs. Got the cable all ordered and everything, next question...

What's the best *lug* to use? The ones I ordered with the cable from Welding Supply are copper, and I know people are making their own from copper pipe. Is copper too "soft" for a high vibe environment? Are there alternatives, and what have been peoples' experiences with different lug materials on these two posts?

TIA...

Steve
 
Hi Steve,

It's a good idea to still use decent terminals. If the welding cable you have is AWG2, then our standard terminals will work great. We used to sell a lot of welding cable, but don't carry it anymore beause demand just slowed down, but we still stock the terminals.

Cheers,
Stein
 
Terminals from Stein, and a few notes

I'm using the terminals that Stein sells. They're the best I've seen. And B&C also sells similar high quality terminals, but at a higher price.

But note that I've found that going by the designated gauge (AWG number) on the terminal doesn't necessarily give the best fit to welding cable of the same gauge. In my case, I'm using Carol brand "Super Vu-Tron" welding cable. And I've found that using a terminal designated 2 gauges smaller than the cable actually yields the best fit. For example, with 2 AWG cable use 4 AWG terminals, with 4 AWG cable use 6 AWG terminals, etc. But that may not be the case if you use a different type of cable or different type of terminal. So my advice is buy a handful of sizes of terminals so you can try them and find the best match for your cable.

Also, FYI, I've crimped these terminals onto the cables with good results using this tool:
http://www.harborfreight.com/hydraulic-wire-crimping-tool-66150.html

Good luck,
-Roee
 
Flying Scotsman said:
What's the best *lug* to use? The ones I ordered with the cable from Welding Supply are copper, and I know people are making their own from copper pipe. Is copper too "soft" for a high vibe environment?
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It doesn't matter if you assure there is no vibratory load at the terminal. Secure the cable to something solid with an adel clamp within 6" or so of the lug.

Anyway, the fancy terminals are copper too...they're simply tin plated.
 
This may be a no brainer for everyone but one little added touch I added was to strip the wire ends (also welding cable) to have a little extra copper showing. Then bent the wire to fit where it was going, once it fit just the way I wanted it I trimmed back all the copper nice and square and added the lugs in there proper orientation. I just felt that by following that process it made for nice strain free wiring.
 
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I ordered welding cable from Welding Supply and used the standard lugs available from SteinAir and others. But, I found that I couldn't get a tight enough crimp (using the Terminal Tool crimper) -- it didn't survive the "pull test". I ended up inserting 3 or 4 short pieces of bare 14 gauge solid electrical wire into the stripped end of the welding cable before crimping and the crimps turned out great. YMMV.

I also used welding cable for the engine ground cable.
 
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Steve, the best quality AWG-2 through -8 terminals I've seen are all nickle plated copper construction. The seam on the ferrule is brazed so it won't separate. They cost anywhere from about $1.35 to about 25 cents based on size. There's no real money to be saved by using copper plumbing pipe and DIY terminals here. Stein sells the good stuff at very reasonable prices.

Also, be aware that the welding cable doesn't have nickle plated conductive strands, so it can corrode inside the insulation jacket. It also may not be heat rated and flame resistant like the MS22759 wire is. Food for thought: you might be replacing the welding cable in 10 years; the 22759 will last much longer - maybe even the life of the airplane.

My advise is to use aviation quality components, especially for the heavy electrical runs in your airplane.

As for what tool to use to swage the terminals in place: all wiring tools have physical limits in terms of force applied, geometric capability, and swaging method. Generally speaking, higher pressure on the terminal means better security. Also, be aware that any wire terminating tool will have a limit of travel which will define the smallest size terminal it can swage. If you put a terminal/wire combination inside the tool that's too small for it to work with, it is possible to create a good looking finished connection, but the connection will lack physical security. That's why we always do a "pull test" of some kind on every connection before its installed. In the case of the Terminal Tool coming up short, that can happen if the wire terminal is too small for the dieset being used: the die will bottom out before the swage is tight enough.
 
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The Terminal Tool

In my previous post I didn't intend to imply that the Terminal Tool was the reason I didn't get a good crimp. The reason was definitely due to the welding cable diameter/circumference being smaller than Mil Spec wire for the same AWG size. I am very satisfied with the Terminal Tool swager and it has worked flawlessly.
 
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Bill Wightman said:
Steve, the best quality AWG-2 through -8 terminals I've seen are all nickle plated copper construction. The seam on the ferrule is brazed so it won't separate. They cost anywhere from about $1.35 to about 25 cents based on size. There's no real money to be saved by using copper plumbing pipe and DIY terminals here. Stein sells the good stuff at very reasonable prices.
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I don't intend to be penny wise and pound foolish...I'll use whatever is the best option.

Also, be aware that the welding cable doesn't have nickle plated conductive strands, so it can corrode inside the insulation jacket. It also may not be heat rated and flame resistant like the MS22759 wire is. Food for thought: you might be replacing the welding cable in 10 years; the 22759 will last much longer - maybe even the life of the airplane.

My advise is to use aviation quality components, especially for the heavy electrical runs in your airplane.
Click to expand...

This is where I think you'll get lots of differing opinions on this forum...the wire may last a lifetime, but it's no good if the fittings fail because the wire is too stiff and the lugs crack and break. Welding cable seems to be a very good option per lots of people with lots of experience (like Stein, Nuckolls, etc.), and reduces the likelihood of the lugs cracking and breaking.

With the exception of the starter and alternator wires, everything else is MS22759.

I have access to industrial (read, expensive) swaging tools, so that's not a real concern here. Whatever is chosen will be swaged correctly, one way or the other...pull tests, etc., done to verify conformance :).
 
Crimp Lugs / Terminals, AMP Brand

Check one of our links for AMP Brand of crimp lugs. TE Connectivity.com. In the search box top right type in AMP Terminals. Stein should be able to provide a nice offering from our selection... Both Solistrand and PIDG terminals meet the highest of Mil. Spec.

Mark C. RV9A
 
I think the reason people use welding cable is that it is far more flexible than aircraft cable, and it is also cheaper (though not by much, IIRC). I used short pieces of it in between my battery terminals and the solenoid/ground they are connected to; this makes removing and installing the battery a LOT easier for me.

Mark Olson RV-7A F1-EVO Rocket
 
marine cable

Bill is correct. The non-tinned welding cable will internally corrode and cause voltage drops which will increase over time.

I was troubleshooting a Corvette with a hot crank problem for a friend that no one could solve. There was a 6 volt drop in the battery cables when the amp demand was high. A hot rod shop had installed welding cable and over a couple of years had multiple similar problems with it.
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Also, be aware that the welding cable doesn't have nickle plated conductive strands, so it can corrode inside the insulation jacket. It also may not be heat rated and flame resistant like the MS22759 wire is. Food for thought: you might be replacing the welding cable in 10 years; the 22759 will last much longer - maybe even the life of the airplane.
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If flexibility is needed, there is marine battery cable available that is tinned and flexible.

George Meketa
RV8
 
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I'm kind of curious how welding cable can corrode internally. Is the insulation porous? Or is it due to the smaller strands?
 
I have welding cable that is over 25 years old with no signs of corrosion. I just cut down a 50 ft piece to make a shorter welding ground and it looked like new. It did not spend the last 25 years in an aircraft, it spent it in an outside shed.
 
Bob, I believe the point of intrusion is primarily through the exposed ends on the wire. Water vapor or liquid can migrate into the wire. Welding cable uses rubber or silicone based insulation, which doesn't hold the strands as tightly together inside as the MIL spec stuff. This gives it good flexibility, but also makes room for corrosive activity.
 
sounds like people are not placing no-ox on the wire before inserting into the lug.

as far as lugs go. Burndy makes a really good product. thats all I use for our electrical work
 
A properly crimped lug is virtually airless, almost a cold weld. I suppose if the lug were to be operated in a salt water environment it could corrode, but in an airplane there is very little exposure to electrolytes, and anything it would be exposed to that could cause a large amount of corrosion would probably have worse effects on the airframe. I plan on inspecting my welding cable segments at the condition inspections, and if need be I will replace them.

Mark Olson RV-7A F1-EVO Rocket
 
crimps

just wondering if you use copper lugs and a crimp what the draw backs of soldering the lugs to get a connection that would not ever come loose
 
turbo super rv-10 said:
just wondering if you use copper lugs and a crimp what the draw backs of soldering the lugs to get a connection that would not ever come loose
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Solder joints tend to be a source of failure if they aren't secured well. As the wire flexes, the stress will be at the solder joint unless it's well secured to prevent movement.
 
Aircraft are subject to large and rapid temperature changes. Summer time operation from altitude where the airframe cold soaks, followed by a descent into hot and humid conditions can condense moisture all over the inside of an airframe - including on and inside wiring connections. And, unlike the wire stored in the shed, our wiring is operational: the resident voltage contributing to corrosive action.

Turbo: the main drawback of soldering large terminals in place is two-fold: First, the solder will wick back under the insulation which hardens the wire, losing flexibility. And, the large amount of heat needed to melt all that solder into such a large body will burn the insulation back, which isn't a good thing and will require heat shrink over the affected burned area.

HOWEVER - having said that - it is possible to solder large gauge terminals in place with a propane torch. Its not going to be especially pretty, and as I mentioned there are some draw backs in the finished product. But it can be done with some care and will yield a safe & solid connection. Bob Nuckolls (Aeroelectric Connection) talks about how to solder on large terminals in one of his newsletters:

www.aeroelectric.com/articles/big_term.pdf

edit: I agree with the observation Bob Leffler made about security of soldered connections.
 
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