Monday, December 15, 2008

Controller Power Input Cables

Remember the Cam-Lok cable connectors? I finally installed a couple of them. I built the cables that are the final terminal into the DMOC controller. As you may recall, 4/0 cable is too thick to pass through the strain relief fittings on the controller. After debating several options, I decided to use 3/0 cable for this section. I got a few feet of red and a few feet of black and went to town.

First, I cut the end of the Cam-Lok connector so it snugly fit over the 3/0 cable:

Next, I slimed the cable with electrician's cable-pulling slime:

Then I pulled the cable through the housing:

I stripped the end the required length (somewhat longer than a crimped lug requires):

Then I wrapped the copper shim around the end, and tightly wrapped the copper strain relief wire about 1/2" below the stripped end, twisting it and laying it against the shim:

I then installed the brass connector and torqued the screws down to spec:

A touch more slime, and I pulled the shroud over the connector and inserted the retaining screw. All done!

I did the black cable too:

There is a problem, though. 3/0 gauge lugs will *not* pass through the strain relief bushings. And they need to - the tolerance on the DMOC is too tight, the ends of the lugs need to be inside the bushings. Also, 3/0 lugs are too wide - I would need to cut the end of one down (as shown in sharpie on the lug to the left). 2/0 lugs, as shown on the right, are "just right".

So, I clipped a few of the fine wires out so the remaining wires would fit snugly in a 2/0 lug, and crimped it and heat-shrunk it (after making sure the bushings were already on the cable *above* the lug connection - oriented properly). A little application of slime let me slide the bushings over the whole thing:

And here are the completed cables test-fit (but not bolted on yet):

Despite the fact that the overall system uses 4/0 cables and lugs for everything, I think this short 18" stretch of 3/0 cable funneled into a 2/0 lug won't affect performance too severely - it is a short distance, and the resistance delta between 3/0 cable and a 2/0 lug at this distance is nearly too small to measure. In fact, I took my multimeter to identical lengths of 4/0 and 3/0 cable, and I could not find any difference in the measured resistance.

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