Soldering vs Crimping

[DaveInDenver]

Watched this video where the fella tested crimping, soldering and crimped & soldered Anderson connectors. His results (which may conflict or reinforce your bias, if you have one) are worth discussing since he talks theory and methods. His test is basically sound, no reason to dispute that he got the outcome he did.

Anderson crimp vs solder

View: https://www.youtube.com/watch?v=TSzUA0T1YD4


The topic is important as a general subject since there's more to it than just finding the lowest resistance.

For one technique and workmanship are critical. If I had one question it would be that his crimps might not be ideal. Anderson, like all manufacturers, has a procedure to produce a correct crimp which requires the right tooling and validation that the tools are working right.

One complaint I make often is cheap hydraulic crimping tools are usually bad news. Their dies are not sized correctly and they can put too much force into the crimp, causing an over crimp. My suspicion is this is the root of why he found what he found. Your crimp needs to reach the cold weld point, where the terminal and individual wire strands all gets pushed together so there's no space and start to become one homogeneous mass, and no further. If you keep squeezing beyond this point the cross section of the wire/terminal starts to neck down. Copper being malleable will displace or in the worst case shear strands. So you'll go from correct gauge to fatter just ahead of the crimp where the material got pushed to thinner in the neck. It's this thinner section where your resistance will spike.

Also, the application on cars dictates that you balance absolute ideal electrical performance with mechanical reliability and environmental compatibility. Having a slightly higher finished resistance is preferred if the termination is more reliable. Soldering introduces several unknowns, which is why you usually only see crimped connections in car wiring harnesses. And aircraft and spacecraft.

So another video showing some of this. He also touches on test methodology and why doing low current testing on a heavy conductor such as this puts into question your results. In the first video he talks about test equipment resolution and error and the second video talks about this as it relates to small vs large magnitude in a large conductor. You may very well see a difference at low voltage/current that at actual high voltage/current are insignificant. IOW, having a connection that dissipates 5W is 50% loss in a 10W circuit but at 1000W is 0.5% loss. The numbers in such a case just tell you information, whether it's a problem (heating, voltage drop, etc) or not is up to you.

Solder vs crimp

View: https://www.youtube.com/watch?v=rJR7hpBOI0o

 

[allen.wrench]

Good topic Dave.

Soldering introduces several unknowns, which is why you usually only see crimped connections in car wiring harnesses. And aircraft and spacecraft.

One major unknown I have seen in my own solder joints is how far solder wicks into the conductor and/or how melted the insulation gets near the joint. When the solder wicks up the conductor and/or the insulation gets melted, the cable in that area will bend and act funny. With enough bending/vibration/fatigue the cable will break.

I tend to prefer crimping for its mechanical behavior more than the electrical. I tend to expect my crimps and solder joints to have close enough electrical behavior in our applications (assuming I made them made correctly enough). Of course I might choose to solder depending on the situation, like for example if a crimping tool could not fit inside a tight space.

Do they talk about solder wicking in the videos? I did not catch it if they did.

Allen

 

[DaveInDenver]

Do they talk about solder wicking in the videos? I did not catch it if they did.

I don't remember and didn't rewatch the videos if they talked about it. It's known technically as solder creep. Solder is supposed to wick, which is to say flow by capillary action. When you solder correctly you control the wicking using flux so solder only goes where you want it. When it goes where you don't it's said to creep.

Solder will produce a mechanical discontinuity where rigidity changes in the wire so when you do this you have to control where a wire is allowed to flex. It's true of a crimped connection too but it's easier to define and inspect visually. You have to x-ray a soldered wire to verify solder didn't creep under the insulation. In either case you have the terminal itself and some length of wire from it ideally held fast (e.g. strain relief) before the unbound length that may move.

An equal concern IMO with solder is introducing new materials, lead, tin, zinc, rosin that can cause corrosion, especially in the presence of salt and acids like battery venting. Look at soldered connections on the outside of most vehicles and you'll see green crusty crap. This is eroding the solder, copper and insulation over time.

 

[Corbet]

I picked up a proper crimp tool recently for my upcoming project. Going to move away from soldering my connection on stuff like winch and battery connections.