# Making Bus-Bars



## RIPPERTON (Jan 26, 2010)

more info. show some pics
dont you just want to bend a piece of flat bar ?


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## GoElectric (Nov 15, 2015)

Hi - that was my original post, different name.

I can't post a pic right now, but I want to braze copper onto copper. Right now we just need to make a right angle to the left on a plated copper terminal so we can make a cable run, but the idea of making bus-bars is tantalizing. 

Currently chasing-down the right welding rods and/or acid-free flux, as it seems entirely doable, but would appreciate hearing from anyone who has practical experience.


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## Duncan (Dec 8, 2008)

Hi GoElectric
Why do you want to "braze" it? soldering is a lot easier and if you have designed your joint correctly should be strong enough physically and electrically

Brazing would be stronger again - but more difficult and more likely to damage your parts


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## GoElectric (Nov 15, 2015)

Hi - I won't pretend to be an expert, but it was the strength thing. That-said, I'm admitting I hadn't thought much about how to design the joint. I just want to overlap two pieces of copper at 90 degrees. 

Sorry, no picks, not at Shop, but if you can make some suggestions, I'll take some pics tomorrow.

J


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## Duncan (Dec 8, 2008)

If you have some spare bits solder them together and then break them apart - test to see how strong they are


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## Tony Bogs (Apr 12, 2014)

I have seen a lot of failed solder joints, caused by repeated thermal expansion and contraction. 
Especially very rigid joints are vulnerable. But it all depends on the size of the joint and kg/cm2. Shear stress in particular (force in the same plane as the joint). 
Bus bars are usually thin with a lot of square cm2 to use for the joint. 
So I don't think brazing is necessary if the joint is say 1/2 square inch + (500A) real copper-solder-copper (not edges only, think 10 bar copper drinking water pipes) and can expand and contract without high mechanical (shear) stress.


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## GoElectric (Nov 15, 2015)

Hello.

Well, after a trial, we brazed together a couple of pieces - one was copper bus-bar from a Tesla and the other a tinned copper terminal. Now we can solder the cable into the terminal without compromising the other home-made connection. Some might just crimp, but a couple of minutes of soldering feels more secure. 

We used a solid copper rod with no flux. No rigorous cleaning and the material flowed well.

Pics below.


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## onegreenev (May 18, 2012)

Did you ever consider TIG welding your copper? You know, you can and it works. Clean and around 200 amps and use helium gas instead of argon. Now I have to go get a third bottle of helium. Im going to give it a go.


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## Duncan (Dec 8, 2008)

Hi GoElectric
"Some might just crimp" - I think you will find that in the industry a crimped joint is considered superior to a soldered one


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## GoElectric (Nov 15, 2015)

Duncan said:


> Hi GoElectric
> "Some might just crimp" - I think you will find that in the industry a crimped joint is considered superior to a soldered one


I walked right into that one, didn't I? I won't defend, just say I'm aware and have my reasons, probably not all of them defensible anyway.

Yes, MM, we considered a TIG, and helium would be fun for other uses, but David is pretty good at brazing, and we wanted the metal to flow into the joint between the two pieces, so getting the whole thing hot seemed a good idea. I saw a guy butt-welding copper bus bars with helium and it looked fantastic alright.

The pic doesn't really show the fill, but the molten copper wicked in there pretty well. 

I would say right now that connection is the most suspect in the whole car, but we will be shooting it with an infra-red scanner.

Correction: it doesn't show the fill at all.


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## onegreenev (May 18, 2012)

GoElectric said:


> I walked right into that one, didn't I? I won't defend, just say I'm aware and have my reasons, probably not all of them defensible anyway.
> 
> Yes, MM, we considered a TIG, and helium would be fun for other uses, but David is pretty good at brazing, and we wanted the metal to flow into the joint between the two pieces, so getting the whole thing hot seemed a good idea. I saw a guy butt-welding copper bus bars with helium and it looked fantastic alright.
> 
> ...


For the lug, I'd crimp it. Im a fan of manual crimping being superior to the hydraulic and solder joint. But a good hydraulic crimp properly done will do the job better than soldering. Less brittle and less prone to break. Ive seen hydraulic crimps just come apart but my manual crimps won't. Period.


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## Duncan (Dec 8, 2008)

Hi onegreen

Ive seen hydraulic crimps just come apart

Can you expand on that - I use a small crimper that I think is intended to be hammered in my shop press

How do they fail?


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## piotrsko (Dec 9, 2007)

Pretty much because a hydraulic crimps cant develop enough force to swage the entire ferrule, whereas the hammer crimp has localized high force areas that lock the wire in place while "shrinking" the ferrule around the wire.


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## EVfun (Mar 14, 2010)

I use a long handle crimper that looks like a large bolt cutter. I seek out Magnalugs because I'm familiar with them and know how to select the right crimper die for them. The lugs are designed for 2 crimps but when setting things up I tested a 1/0 cable with a single crimp. I bolted it up to the door frame in my garage and hung my weight on the cable (about 200 lb.) and bounced on it. No failure. I cut the crimp apart and the tiny individual strands where no longer round from the pressure applied. When I'm installing cables in my car they are double crimped as designed, and covered in heat sealant lined heat shrink. I have never had the resistance of a cable go too high, though out of hundreds of crimps I did have one gain enough resistance that I replaced that battery jumper (about 12 inches of cable and 2 new terminals, back in the days of Lead.) It is hard to accurately measure absolute resistance when it is so low, but this one crimp was about 1 to 1.5 milliohm higher than the rest, letting the terminal get somewhat warm after a spirited drive.


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## GoElectric (Nov 15, 2015)

Super-helpful, thanks.

Jim


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## favguy (May 2, 2008)

I'm a big fan of using a hammer crimp. It may not be as pretty as a hydraulic crimp, but it is very effective. Before making up my cabling, I did a couple of tests. Having cut through the centre of a couple of hammer crimped lugs, the results were very impressive, the crimped area was so well crimped it looked just like solid copper.


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## onegreenev (May 18, 2012)

Nice and solid like this. 

I like this version of the crimper vs the one i use in the video. This one is better.


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## QMANDLL (Oct 19, 2014)

More juicy stuff - nice job. Very convincing at the end.


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## Frank (Dec 6, 2008)

Crimp then solder for the lugs, best of both worlds...


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## Duncan (Dec 8, 2008)

Hi onegreen

I have one of those blue "hammer" crimpers 
But I use it in my 12 tonne press - the results look just the same as your hammered one 
I think I have a little bit more control


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## PZigouras (Jun 5, 2010)

I've been using these lugs for a while now, and they work great for various projects. Not cheap, but not too much more than a standard 2/0 lug either....

https://www.electricalhub.com/generic--tin-plated-copper-elbow-lugs


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## onegreenev (May 18, 2012)

Duncan said:


> Hi onegreen
> 
> I have one of those blue "hammer" crimpers
> But I use it in my 12 tonne press - the results look just the same as your hammered one
> I think I have a little bit more control


Sweet, never considered using it in a press.


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## GoElectric (Nov 15, 2015)

Hi. Yes to the press alright. 

And thanks to PZig for the lead on those lugs - that would have saved a lot of time and I won't have to worry about the brazing. At first glance I thought it was $30 each, but for 5, that's okay. 

Live and learn. I still kinda think the one we made would work, but until I get an infrared camera to see if it warms up, cannot say. Not even sure how I will be able to run that test, as the lug would have to be in place and taking 500 amps.


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## major (Apr 4, 2008)

GoElectric said:


> Live and learn. I still kinda think the one we made would work, but until I get an infrared camera to see if it warms up, cannot say. Not even sure how I will be able to run that test, as the lug would have to be in place and taking 500 amps.


They make those for at least 4/0 cable. 325A continuous for most 4/0. Would take 500+A for quite a while. I've done battery testing with this size or even smaller (1/0 & 2/0) up to 800A for like 5 minutes or more. 

http://www.quickcable.com/products.php?pageId=340

I've made and used many busbars. I like the method. But not for cable ends. Nothing beats a high quality lug properly crimped with the right tool and die.

major


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## onegreenev (May 18, 2012)

GoElectric said:


> Hi. Yes to the press alright.
> 
> And thanks to PZig for the lead on those lugs - that would have saved a lot of time and I won't have to worry about the brazing. At first glance I thought it was $30 each, but for 5, that's okay.
> 
> Live and learn. I still kinda think the one we made would work, but until I get an infrared camera to see if it warms up, cannot say. Not even sure how I will be able to run that test, as the lug would have to be in place and taking 500 amps.


If you go the manual route and use a press be sure to put a tiny amount of grease on the tip of the crimper to prevent tear out of the copper on those thick lugs lugs. Just a tiny amount. A little goes a long way. Be sure if you to figure out the right distance for the press so you don't over crimp and you get consistent crimps. Or just go the hydraulic methods. Not my first choice unless doing hundreds of crimps.


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