# Solid bus bars vs cable and lugs



## evmetro (Apr 9, 2012)

Does it make much difference if I were to fab some flat bus bars out of copper sheet vs making cables with crimp lugs? I want to link my controller up to the five lugs just behind the controller, and was considering doing just the 3 phase section with the solid fabbed bars utilizing the 3 bulkhead lugs all the way to the right in this pic. It looks like I could do 2 of them in an L shape, and then the 3rd would be straight. The lugs that go through the gas tank are already going to introduce more resistance, so I want to do the optimum bus bars for the lowest resistance. Thoughts or recommendations?


----------



## major (Apr 4, 2008)

I like bus bars vs cables with lugs for cases like this. You eliminate the interface (contact drop) between the cable and lug. However you also can eliminate any flexing the cable could provide. Depending on the component and mounting of such, this can stress the joints or promote loosening due to vibration. That is why laminated bus bars are often used. They can provide some flex while still eliminating the lugs and offering better resistance.

Also, cable lugs are often plated. Homemade busbars not so. They can be prone to corrosion. I have used a liquid tin plating product on my copper bars before. And I know guys who send them out for nickel plating.


----------



## evmetro (Apr 9, 2012)

major said:


> I like bus bars vs cables with lugs for cases like this. You eliminate the interface (contact drop) between the cable and lug. However you also can eliminate any flexing the cable could provide. Depending on the component and mounting of such, this can stress the joints or promote loosening due to vibration. That is why laminated bus bars are often used. They can provide some flex while still eliminating the lugs and offering better resistance.
> 
> Also, cable lugs are often plated. Homemade busbars not so. They can be prone to corrosion. I have used a liquid tin plating product on my copper bars before. And I know guys who send them out for nickel plating.


I will go with the fabbed bars then. I saw some sheet over at my metal supplier that was a little thicker than the 2mm that I have been using for the HVDC circuit that will take up a little less width and space, since the lugs on the controller and the bulkhead are a little narrower. I have been maintaining 68mm cross section area in all the HVDC circuit bus bars... is this still appropriate for the 3 phase section?

I may pull all the bus bars in the whole car when it is completed, and have them plated.


----------



## dougingraham (Jul 26, 2011)

evmetro said:


> I have been maintaining 68mm cross section area in all the HVDC circuit bus bars... is this still appropriate for the 3 phase section?


The three phase cables are only utilized 2/3 of the time but they will see higher currents than the battery cables. 68mm is more than enough for anything except drag racers.


----------



## evmetro (Apr 9, 2012)

The fabbed bus bars flex very nicely. The side to side, or (tensile?) give is not as nice, but there is a little via bus bar flex. I like it, it feels right. Thanks you guys for the input.









.


----------



## racunniff (Jan 14, 2009)

evmetro said:


> The fabbed bus bars flex very nicely. The side to side, or (tensile?) give is not as nice, but there is a little via bus bar flex. I like it, it feels right. Thanks you guys for the input.
> 
> .


It might not hurt to slip a little heat-shrink tubing over the middle of those just to prevent weird shorts.


----------



## Duncan (Dec 8, 2008)

I have made something similar but I used three much thinner pieces for each busbar 
So they were laminated together


----------



## sabahtom (Mar 1, 2011)

By laminated, do you mean pressed together by the bolts at either end? What thickness of copper did you use?


----------



## Duncan (Dec 8, 2008)

sabahtom said:


> By laminated, do you mean pressed together by the bolts at either end? What thickness of copper did you use?


Yes - 0.8mm thick - just what I had lying around


----------

