Connections are the weak link in our electrical systems. The fundamental keys to success are to use the properly matched, quality terminals, to put them on with decent tools, and to keep out moisture.
Historically, many terminals on boats have been soldered onto their conductors. This is explicitly rejected in current boatbuilding standards, which do not permit solder as the sole means of connection. This is because the solder turns a stranded conductor into a solid conductor, which, with vibration, is liable to fracture at the point where the solder ends. The only exception is battery lugs with a solder contact length of not less than 1.5 times the diameter of the conductor. Even here, it is better to not use solder.Â
From an electrical conductivity point of view, solder is no better, and maybe not as good as, a properly made crimp connection. That’s assuming the crimp is done correctly, which unfortunately is often not the case!
Terminal Features
The first thing is to ensure you are using quality terminals. Key construction features are:
- The terminal material must be tin-plated copper and not tin-plated steel, which is found in many automotive terminals; you can test with a magnet – the steel is magnetic, whereas the copper is not.Â
- The barrel to which the crimp is applied should be seamless (i.e., welded shut) and not simply formed by bending the two sides of the crimp portion of the terminal into a tunnel, leaving an open seam down the middle.Â
- The metal in the terminal needs to be sufficiently thick, and the barrel long enough, to ensure an excellent connection.Â
- Ideally, the barrel will be serrated on its inner side to enhance its grip.Â
- Terminals for large conductors will have the barrel closed to prevent moisture ingress.Â
