Join Date: Aug 2008
Location: Near Gainesville, FL
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Designing and specifying parts for cable assemblies is what I do for a living. In my case, for military vehicles, military and commercial jet aircraft, space applications (satellite, shuttle and Orion) and Navy shipboard. I also teach basic crimp theory to the manufacturing and engineering teams at my customers.
Much of what is noted above is dead on. Without going into a great deal of technical mish mash, if you want a connection that will last the life of your vehicle, use a proper crimp tool. You must crimp. Your mechanical strength comes from the crimp. Gather together all your goodies then find someone who has a crimp tool already and borrow it. The cheapest one we sell is about $ 600, and it is only an occasional use tool. The cheapest really good one we sell is about $ 4K. The Harbor Freight tool sounds like a good idea, though I haven't seen the crimp profile.
A vise will work, for a while. However, a good crimp creates what is called a gas-tight cold weld, and there is a very specific profile for the crimp barrel in order to obtain this, and you can't get that without a contained die set. With a vise you run the risk of over crimping. Copper wire is soft and will flow. Imagine grabbing a banana in the middle and squeezing. If you overcrimp with the vise, you will start out with 4 awg wire and squeeze it down to 6 or 8 awg. That will create excessive heat and premature failure.
Worse case, the local golf cart store will have the hammer kind. Maybe you can work a deal with them. It's a pretty sad crimp, but better than nothing.
Terminals: AlterEgo knows his stuff. Definitely silver plated if you can find them. Very expensive compared to nickel or tin. We manufacture them and even I can't get them. Nickel is second best, tin is third.
Open ended crimp versus the closed end tube style: open ended is fine if properly crimped. Closed end absolutely must be properly crimped. If you just solder, you have little mechanical strength and a possible path for fluids, then corrosion. If it's properly crimped it should not wick solder underneath into the barrel. If you are using bare copper wire, solder it anyway.
My aircraft and satellite manufacturers I work with will only allow crimp. Solder-only is not dependable long term.
SAE (Society of Automotive Engineers) drives a lot of the specs, and even they don't require solder. They like it as a backup though. Most heavy truck manufacturers will solder dip the terminal after crimping for an extra layer of protection, so heat that sucker up and flow solder over the exposed wire. For battery applications, always add the adhesive lined heat shrink as a backup. It needs to be adhesive lined. Just regular tubing will let in contaminated water then trap it, accelerating the rate of failure.
Do not get any insulation inside the crimp barrel. Insulation, when crimped, can be ridiculously strong. It will cut through strands, turning your 4 awg into 8 awg.
Finally, head down to the marine store and spend a few extra bucks on tin coated wire. Not bare copper, but pre-tinned. It has far better corrosion resistance than using plain copper. Get something rated to at least 105C, not 85C.
Upsize the wire to the next larger gauge, as suggested above. Minimal cost increase, great insurance, better voltage characteristics.
If you can find it and afford it, use a cross-linked mil spec jacket, not just PVC. That will take anything you can throw at it. I've no idea where you can buy that. We manufacture it, and I picked some up from the factory in 4 awg recently. Rewired my golf cart with it so I never have to replace the cables again.
PM me with questions. Might be able to get you some samples on a limited basis. We also mfg the heat shrink, the terminals and the tooling.
Last edited by GunnersJK; 01-04-2010 at 03:29 PM.