Do you crimp the ends or solder them and why?
Ends are crimped. The manufacturer of the ends recommends crimping. Cables are crimped using a 12-ton hydraulic crimper. It squeezes the cable so tightly there are no air gaps or spaces (I've seen the pictures of cross sections). Soldering is tough on the insulation and the solder wicks up the wire destroying the flexibility. Soldering also requires flux, hazardous lead solder and solvents (for cleaning the flux). The extra cleaning step adds cost and environmental issues I don't want to deal with. Besides the ends are crimped so tightly that there is no room for the solder. So, soldering presents a lot of problems for little or no reward. As a small business, I don't want to deal with chemicals and all the problems they cause. I'd contend that the crimped connections are so tight that they have lower resistance than soldered terminals... what's the resistance of solder versus the resistance of copper wire?
What's the difference between positive and negative cables?
Besides the color, the difference is the size of the battery post. Positive posts are slightly bigger (larger diameter) than the negative posts. That's why those cheap "universal" battery terminals never fit quite right. They're too small for the positive post and too big for the negative.
Can you make me a cable for my ?
If you tell me how long it needs to be, then I'd be happy to make you one. However, at this time I don't have any way to look up how long of a cable a specific application uses. Unfortunate but true. If you know where I can look this info up, or have a book which shows it, please let me know.
What do you recommend for 6 volt electrical systems?
Six Volt systems take twice as much current to do the same work as 12V systems (Power = Voltage x Current). The battery cables should be sized to handle that increased current. I'd use 2/0. You can't go wrong with that and it does not cost much more than 1/0. I would not go any smaller than 1/0.
I have a Jeep Wrangler with a goofy 2 hole connection on the lead that goes to the junction box? Can you make me a cable with one of those?
I'm working on finding some of those 2 hole connectors. I know that someone makes them I just haven't found who. Most guys cut the end off the factory cable and use it as a jumper between to 2 holes.
My negative cable has a terminal in the middle that grounds to the body, can you make that?
I have some "double barrel" lugs that work as those middle-of-the-cable chassis ground terminals. They only come in limited sizes. Alternatively, you could get a ground cable with an extra wire that goes to the chassis ground. In other words, if the middle-of-the-cable chassis ground is 15 inches down the cable, get a ground cable with a 15 inch aux lead that goes to the chassis ground.