[brian_]

Since this thread has been revived, a couple of follow-up comments:

And how about having them lasercut?
In The Netherlands there is a company that has up to 3 mm Copper (CU-DHP-R240) which they can cut. The challenge however is that single piece production is still quite expensive. Two of the same product is only a little more expensive than a single one. So it only helps if you can design in such way that you have multiple of the exact same busbars.

There are now more services to do this sort of work. SendCutSend (available only to customers in the U.S.) now laser-cuts copper up to 0.250" (6.3 mm), and mentions busbars as one of the applications; they will also do limited bending and tapping... but they won't plate it, so that would be a separate process after the busbars are cut, tapped, and bent.

Yes copper is more ductile but I can't see any good reason not to use Aluminium , Aluminium is used extensively as power transmission cables and bus bars.
...
Copper or aluminium? Which one to use and when?

If you are using Aluminum, you really should have it nickel coated, at least in the parts that are contacts, as Aluminum develops a resistive oxide coating.

As the article in Electrical Engineering Portal noted, both copper and aluminum are normally plated with silver or tin, rather than nickel.

 

[remy_martian]

Copper bus bars for high voltage switchgear are normally nickel plated. Tin is horrible in high electric fields - it forms dendrites.

Tesla's busbars appear to be naked copper - not sure if there's a passivation spray on them.

 

[cricketo]

Those guys have reasonable prices, considering you don't spend any time making that stuff.

I got my flat bar from Amazon, but it was sold by OnlineMetals. I think it was this one : Amazon.com: 110 Copper Rectangular Bar, Unpolished (Mill) Finish, H04 Temper, ASTM B187, 1/8" Thickness, 3/4" Width, 72" Length : Industrial & Scientific
Ended up costing $80 delivered for two 72" pieces. So to compare to above quote, that would be $0.44 plus labor per bar vs $5.8 per bar.

 

[brian_]

Copper bus bars for high voltage switchgear are normally nickel plated. Tin is horrible in high electric fields - it forms dendrites.

Of course there are no high voltages in an EV, by utility standards (where high voltages are many kilovolts, not just a few hundred volts).

The inside of a lithium-ion battery box or EV high-voltage distribution box may be a nice enough environment (compared to open installations in industrial settings, for instance) that corrosion isn't a big issue. I don't know.

 

[remy_martian]

^^ Looks like you paid for, but didn't get, ~3 more pieces with the minimum order adjustment.

 

[cricketo]

^^ Looks like you paid for, but didn't get, ~3 more pieces with the minimum order adjustment.

Well, I just wanted to see what the service would look like in practice. I think it's decent. There is a weird time/money optimization happening in these projects: on one hand your and my time aren't worth making bus bars by hand, it's better to pay 30-40-50 bucks and have them delivered with laser-cut precision. On the other hand sometimes I can't wait 3-4 business days, and sometimes I am just bored. So I guess in the end it depends...

 

[remy_martian]

That and machining copper can be biotch.

I keep putting off getting copper for bus bars and it keeps going up in cost 🤬 $4.60/oz last I looked

Another reason to use these kinds of services is you only get what you need vs a sheet or 6ft length (or two) of it

 

[cricketo]

That and machining copper can be biotch.

That's the common wisdom! But I absolutely had no issues machining my ingots. I used a slitting saw to get the top off, then shell mill to square up the stock, then just a two flute end mill like if going against aluminum. I think a thing to mind is annealed copper, which can feel a lot more soft.

 

[BlueHorizon]

@cricketo I purchased a similar bar (albeit 1/4 thick) from Amazon from the same vendor and machined my own busbars. I was able to cut the bars by hand using my Dremel Ultrasaw with a metal cutting wheel with a vice securing the bar. I then used my drill press to create the holes, leveraging cutting fluid (Tapmagic) to try to stop the bit from clogging up as the copper would get hot quickly. Definitely had to be progressive and move the drill up and down several times to remove some of the twisted debris. For the larger holes I used two drill bits, one acting as a pilot. I then did a quick polish, although nothing too great but I’ll be applying copper paste on the terminals.

After all that I realized that I could fit the heat shrink from some of the 2/0 lug kits I had from Amazon around the bars.

We’ll see how these work out..