Saturday, November 29, 2008

Making Short Interconnects

Today I also started working on the battery interconnects. They will be made from 1/16" by 1" copper bar stock - three pieces for each interconnect. This is so the cross-sectional area (0.1875 square inches) will roughly match the 4/0 welding cable (0.1662 square inches). I could have gone with sold 3/16" by 1" bar stock, but that will be very stiff, and I worry that it will tend to lever the screws out of the batteries as they vibrate.

Anyway, I started with the hardest ones - the short pieces. I cut 24 pieces 3.5" long:

I then bent them to give them a little spring. I started by dividing the bar in quarters:

I then bent both end quarters up by 45 degrees. I used my favorite vice-grip clamps to do this:

Here are the ends bent up:

To create the bend in the middle, I built a little jig. There are two pieces of 3/16" by 1.5" angle stock nailed into a 2/4, and two pieces of 1/8" by 1" angle stock which are the press parts (it's handy that I keep all my waste chunks of metal in a box for future use). I use a bar clamp as the press:

Basically, you insert one of the 1/8" by 1" angle stocks into the valley, then put the copper strap on. Then you put the other 1/8" by 1" angle stock on top, and clamp it down. Screw it down as tight as you can, and you'll end up with a nice 90 degree bend in the middle:

Here are the completed pieces, ready to be drilled and installed:

I should be able to reuse my jig for other 90-degree bends that will be required.

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