# Copper Bus Bar



## Tesseract (Sep 27, 2008)

You definitely want silver, tin or nickel plating for copper bus bars in high temperature applications. At DC to 60Hz there is some controversy as to which plating is the best because while silver has the highest conductivity, it is also more noble than copper so it will actually accelerate corrosion wherever the plating gets scratched. Thus, you don't want to just use toothed lockwashers, for example, in between a nut and the bus bar (i.e. - use a flat washer, too).

In my opinion, tin plating is the best, practically speaking, because it protects the copper, has reasonably low resistance (higher than silver or copper but lower than nickel) and can be easily applied yourself using "electroless" plating kits such as "TINNIT" from, for example:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=340-188

BTW - That 12" length of bus bar will lose approx. 10W of power at 500A


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## Twilly (Jan 22, 2008)

I work with all DC products, and we use tin plated connections.

Also, when sizing your buss bar, you want the same cross sectional area as the equlivant solid copper wire...

http://en.wikipedia.org/wiki/American_wire_gauge


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## madderscience (Jun 28, 2008)

One issue that is frequently brought up with bus bar is that it can put additional stress on battery terminals Vs. cabling, and the connections are more likely to work loose. So if you are going to use it, make sure your batteries are well secured and your battery boxes are solid so that the batteries do not shift around or flex relative to each other during driving. Favor a bus bar that is fairly thin but wide (to get enough conductivity) and design them with "kinks" in the middle so that they can allow slight movement between the batteries.

Good Luck.


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## Tesseract (Sep 27, 2008)

madderscience - you bring up an excellent point and it is one I totally agree with: bus bars are for making rigid connections between points.

ClintK was only asking about using a bus bar to make the field to the armature connection on his motor, I believe... correct me if I read that wrong, ClintK.


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## ClintK (Apr 27, 2008)

Tesseract said:


> madderscience - you bring up an excellent point and it is one I totally agree with: bus bars are for making rigid connections between points.
> 
> ClintK was only asking about using a bus bar to make the field to the armature connection on his motor, I believe... correct me if I read that wrong, ClintK.


That's correct, I'd only like to use one between the field/armature motor terminals. Good info guys, I appreciate it - looks like I can use a fairly small bus bar when compared to equivalent copper wire area. I'll go ahead and put this info on the wiki page.


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## tj4fa (May 25, 2008)

Seems like a lot of $$ for a hard bar as compared to copper welding cable.

How significant a difference is the hard copper bar as compared to 00 welding cable and the plated copper lug connectors?


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## madderscience (Jun 28, 2008)

I really shouldn't read and reply to posts after midnight. Copper bus bar is certainly the best way to go on rigid motor terminals. Go for it.


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## fugdabug (Jul 14, 2008)

If you have access to a good metal cutting blade and jig-saw or a scroll-saw with a metal cutting blade, BUY THE SHEET in the desired thickness. Cheaper and you can customize your needed 'bar'. You can then also use a propane torch to 'anneal the copper to work or bend it.
And a hand drill with some good sharp bits will always provide good puncturing capabilities for necessary holes... just a thought.

I have been working with 14ga. sheet material using the tools above for a few years in my metalworking (along with thicker and thinner materials of copper, brass and silver). It is far more inexpensive to find the non-precious metal materials at a good hardware store or supplier and make the items yourself.

As for plating, tin (non-lead bearing) solder can work, but it may sweat at a higher temperature... SO having someone with a hobby plating set-up will make doing it right much better!!! (or buying a hobby plating transformer and some acid and cyanide will provide you the ability to do at will) NICKEL is the metal of choice. It is used to 'flash' the copper bar material, prior to plating with silver, and thus PREVENT CORROSION by 'sealing the surface of the copper. Then FINE SILVER is used to do the final plate, but the Copper is a naturally oxidizing metal, that is why it is noted for its 'green patina' and why the planet Venus is considered the Goddess of Copper... if it is just straight plated with SILVER, it would be useless as the corrosion will start and the bar will blister with copper oxide and shed the silver. NICKEL and SILVER don't melt like TIN will at a temperature under 1000 degrees. (NICKEL = @1100 deg f, SILVER = 1470 deg f) Hope this helps.


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## Technologic (Jul 20, 2008)

tj4fa said:


> Seems like a lot of $$ for a hard bar as compared to copper welding cable.
> 
> How significant a difference is the hard copper bar as compared to 00 welding cable and the plated copper lug connectors?


My guess is a bus bar would cut down on wire induced inductance (from windings).


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## ClintK (Apr 27, 2008)

I went ahead and made a wiki entry with everything discussed here. Please feel free to edit / correct as desired.

http://www.diyelectriccar.com/forums/showthread.php?t=24828

Thanks all!


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