what causes a Burnt Harness?

So i finally got my harness for recitfierregulator.com, im a bit dissappointed that the connectors for hte battery side of the rr didnt fit, but i got it real quick. the clip didnt work either. but its in and seems to be charging. 14.4 v across the battery.

but again, what caused the problem in the first place. obviously the 2 stator wires shorted, the plastic was pretty hard, did it simply brake and make an non insulated area? i cannot imagine a foreign material got into it, wouldent that cause a burn at the opening, not deep inside?

i suppose there is no real way to know for sure. im heading out of town. i just hope it keeps charging.

 

All high current connectors are subject to failure from moisture-induced corrosion, particularly if they are friction-fit instead of clamp style; clamp style being a ring terminal held in place with a fastener (such as a battery terminal). Once a little bit of corrosion forms, the connection becomes a "voltage drop"; it becomes an electrical load instead of a straight electrical connection, as Singer732 pointed out. Typically, the connection that has turned into an electrical load gets hot, which in turn causes it to get more resistive, which makes it get even hotter, which makes it get more resistive, etc. I believe that part of the issue is that the metal in the connectors start deforming due to the heat, so that the friction fit that is relied upon starts loosening up. At that point, the surface area of the metal-to-metal connection is reduced, so the resistance goes up, etc, etc. It eventually gets hot enough to start melting all of the plastic surrounding the contact, which starts flowing into the contacts and making the problem even worse. Then the heat starts melting the insulation on the stator output wires.

The stator doesn't know about an excessive electrical load; it just keeps putting out electricity. When the electrical load gets to the point that it exceeds the stator windings output capacity, the stator windings start getting hot which eventually melts the thin varnish insulation on the copper windings. Then the windings short together and create a localized load, which would pretty much be a direct short circuit. Motorcycle charging systems tend to be primitive, compared to automotive systems. They typically always run in full output mode because they use permanent magnets in the alternator; the magnets can't be 'turned off". So generally an output value is selected that will fulfill all of the requirements of the bike in addition to some reserve capacity for anticipated accessories (heated clothing, GPS, etc.). The reason the R/R is so big is that it has to handle all the heat generated from a charging system that is always in full output mode.

FWIW, most friction fit connections are somewhat self-cleaning if they are occasionally separated and rejoined. The contacts areas drag across each other and wipe away some of the surface corrosion. However, once the plating on the metal goes away, corrosion rapidly sets in, especially in a humid environment.

You'll see the same type of failure in a standard house receptacle, particularly in a bathroom that has a hair dryer left plugged in.

 

Damn you Lgn the terrorists have won!

 

Don't you think this is the EXACT kind of reaction he's looking for? If you ignore him, he will go away or stop being such an annoyance to the general population. Stop posting in his threads, don't chat or PM with him just ignore him. He knows he's gotten under your skin so why would he stop? Take yourself to another level and move past the :bs:

 

The war is never over. One battle at a time...

In the end, there will be no more terrorists; it's part of my master plan. :smile:

Actually, I replied because it was a valid question that I could answer. Sorry, JD! I promise to control myself from this day forward. Hmm. "Promise" might be a bit too strong; I'll TRY to control myself from this day forward. :biggrin:

 

+1 to this. I have been guilty of reading his dribble. This is a great bike, great site and great people and he knows it. Who cares why he does it, he probably wears a Triumph Sprint T shirt and the VFR is his wifes.
I WILL Ignore!!

 

Oh and thanks lgn001 for the write up :thumb:

 

He will reveal himself soon enough