Letter Re: Anderson Powerpoles: The Legos of DC Electronics

Jim,

While it’s true that Anderson Powerpole connectors can be soldered, this is usually not a good idea, for several reasons:

1) Soldering is weaker than crimping because it interposes a soft metal– and possible air voids– between the copper of the wire and the copper of the terminal. A properly crimped connection places the wire in compression and the surrounding terminal in tension, ensuring a mechanically strong joint.

2) Soldering adds resistance to the connection. In a properly crimped connection, there are no gaps at all between the wire and the terminal. However low the resistance of solder, it’s higher than nothing. In the extreme case, soldering is completely unacceptable for joints in lightning protection systems, since the high current of a lightning strike will hit the extra resistance of the solder, vaporizing it, producing a small explosion and sending the current in search of a better connection to ground– for example, through your radio equipment. Crimping and welding are the only acceptable options for those connections.

3) Soldering degrades the long-term reliability of the connection. Some types of solder and flux can trigger chemical changes that will embrittle copper wire. Solder also has a different thermal coefficient of expansion than copper, so over time, heat cycles create stress at the surfaces of the wire and terminal that can produce microscopic cracks and eventual separation. I’ve found soldered connections in old radios where the wires were physically loose within a visually perfect and undisturbed sleeve of solder.

4) Soldering degrades the long-term mechanical strength of the wire itself. When solder wicks up into stranded wire or around solid wire, it makes the wire stiffer. The last point reached by the solder becomes especially likely to kink and break because the transition from the soldered section to the unsoldered section concentrates bending stresses at that point. As with any stress concentration, this can lead to wires being broken by relatively mild stresses, including simple vibration. Stranded wires will die faster than solid wires, one strand at a time. I’ve also found many soldered connections where the wire was broken off INSIDE the insulation, right at that point, leaving soldered strands on one side of the break and loose strands on the other.

Because of this tendency for soldering to create stress risers, wires that have been soldered to Powerpole contacts should have a cable clamp installed at some distance from the connection to prevent the soldered joint from flexing. The Underwriters Laboratories (UL) standards require such clamps, as Anderson Power Products notes on its own web site, and when I was doing this kind of work, military and aerospace connectors were not allowed to use soldered contacts at all.

In amateur radio and similar applications, Powerpole connectors are almost always used with unsupported stranded wire, and high-quality crimping tools will absolutely give the best results. (And the same is true for ring and spade terminals, butt splices, and similar connections. Crimp all of these, don’t solder.)

On the other hand… in an emergency situation, considerations of strength and long-term reliability can be ignored. In my vehicle emergency kit, I carry a small butane soldering iron and solder rather than crimping tools to go with a small assortment of electrical terminals. – P.N.G.

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