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[aprssig] 12V Wiring and Crimping

Steve Noskowicz noskosteve at yahoo.com
Sun Oct 30 19:11:06 UTC 2011


Can't resist pointing out some things...

Primarily, that all these absolutes are flat wrong.  Never say never and never say always... Life is a middle of the road sorta' thing. (;-)


>... So why is the second most common electrical failing on
> older cars etc, more often than not, a bad crimp connection?   

Well... when all you have is crimp connections what else is there to fail to compare with, eh...?  You can't compare crimp failure rates to spark plug failure rates. (How many soldered connections are there in the same car to compare failure rates with?)


> > Solder wicks down stranded wire and causes loss of
> flexibility and potential for vibration fatigue cracks...
> If not done correctly, yes it does.  Done right, not a
> problem.  

This is the key in BOTH methods.  
- Soldering any old wire to any old terminal with less that excelent technique in a poorly suited enviroment increases the probability of failure.
- Crimping with any old tool and any old wire in whatever terminal in a poorly suited enviroment increases the probability of failure.

  Hey! not everyone has all the perfect skills and tools - we're hams.  Stuff will fail at rates depending on the above factors.

P.S. I've also seen quite a few dangling strands in crimp connections - they can have fatigue failures also.



> So that's why they go green and fail when used in "moist"
> areas then?

  I think that's a red Herring. Copper sulfate is green.  Copper terminal/wire + environment = Other compounds -- regardless of the presence of a crimp or PbSn solder.  Rubber gets harder (slow-vulcanizes) because of sulfer in the air.  Air aint't just O and N.  The boat folks like the hot-melt/heat-shrink coverings for this (anti-green) reason...makes the environment friendly.


I paraphrase:
> > nothing is more reliable than a properly designed [and executed] crimp connection.

  Except I won't support the "nothing"; just the concept that when done by the book, crimp is just fine -- this includes using them in the correct environment.  I maintain that some Molex or other crimp connectors are used by manufacturers where they shouldn't be used.  
  OTOH, when you can't crimp it correctly, a *GOOD* solder job will do just fine - this also includes the environment thing.

  Put solder connections in an environment better suited to crimp and the crimp will prevail AND visa versa.

  Some of the heavy duty radio control guys use the small Anderson units at close to 100 amps and love em'...



> > We hams are often casual about making crimps and then complain about 
> > their performance. We have only ourselves to blame.

  Amateur means amateur and the variability that comes with that title -- and that's ok.  Enjoy the hobby and it's faults as well as your level of ability.  When you have lots of skill and experience, do some neat thinga and, heck, go ahead and brag.  By the same token, when you lack a skill, find a work around and enjoy your accomplishment, or cry about your lack thereof and move on.

  In the extreem ... Don't shoot the screw driver manufacturer when you stab your finger prying a paint can.



> And I have seen many instances of Molex connectors burning up...

I never did like the tin plated versions.  They look corroded from the start, whereas gold looks pretty, well, pretty.

  Do your best then live with the results, guys.

73, Steve, K9DCI 
Gotta move on.



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