Genie soldering is not preferred for high vibration environments. Crimping is considered more reliable. Proper strain relief and anti corrosion treatment is key.
It's not preferred for inline connections, but context is important. In a field installation, you can do up a solder-type butt splice with a lighter if you really need to, whereas crimping requires specialized tools.
True enough, but I would take it one farther and say that a properly executed hand splice is arguably preferable to solder if vibration is a factor. Also, even less tools needed, though not everyone carries a little tube of conductive grease with their electrical tape. (But they should, it makes a decent splice immune to corrosion and a solid, “permanent” repair. )
I have had many, many soldered splices fail on generators, marine engines, other long running equipment.
They just break where the copper meets the solder joint. Copper generally has poor fatigue characteristics, depending on the alloy.
Some of this also comes down to harness design and how it's put back together after the splice. Ideally, the exposure of the splice itself to flexing is very low. I reckon if it's strain relieved/mechanically fastened well and encapsulated, it doesn't really matter what style of splice you use.
Yes, strain relief is key. Even more so for soldered connections where vibration is significant. But really, no joint is immune to problems without some kind of strain relief to prevent stress concentrations at the rigidity transitions.
I agree that soldering probably won’t produce any issues if the wire is not subjected to significant flexure or vibration, or if it properly strain relieved and secured to a bulkhead so there is no movement at the limit of solder wicking. It’s just that I’m usually too lazy to do that perfectly, so I tend towards more forgiving solutions in vehicles and equipment. But sometimes, solder is the one true way, and I always feel better about soldered joints even if I know I’m statistically wrong.
As for wire being 100 percent copper? I’m not sure, but I have definitely noticed different rigidity of copper fibers. Might be impurities, annealing, or work hardening from the drawing process… but there is definitely variation. Some wire can be really susceptible to fatigue cracking, while others seem relatively immune. Not sure of the why.
Also, don’t even get me started on copper plated aluminum fiber wires.
