Do you smell something?

[buster]

So this weekend had some progress followed by some setbacks.

I had the bike running (if only with the choke all the way out) and at the point where I decided to shut down I heard some snap, crackle and pop along with a very familiar electrical smell.

I tracked it down to a large rubber boot down by the battery that ranged from really warm to molten lava at some spots upon pealing it out of the way I found this burnt electrical connector

Wich turns out is the connector from the rectifier assembly into the bike's wire loom. I am guessing it is safe to assume the rectifier is shot or do I have bigger issues?

Anyone ever seen this problem before? Is replacing the rectifier going to resolve my issue?

 

[Guest]

It may be just excessive corrosion at that connection causing the overheating and meltdown. Clean the area or bypass the wire and solder it and try again. 0.1-0.3 voltage drop over significant amperage (20-30 amps?) is up to 10 watts of heat, which is enough to melt rubber and plastic when localized and insulated.

 

[buster]

Its a thought...there was definatley corrosion. Here is a closeup

 

[tomm]

Just a comment about burned connectors before you start replacing stuff. Things get hot when there is a current flowing through a resistance (think light bulb). Watts dissipated is current squared times resistance. Connectors should be very low resistance, essentially zero, so watts dissipated should also be about zero. If the resistance is high, then the current flow is low (volts = current times resistance), so again, watts dissipated is low. The problems come in when the current is high and the resistance is low. Say you have a bad connector with a resistance of 1/100 ohm. This is very low in comparison to the overall resistance of the bike as seen from the battery, so not much voltage drops across it (0.1 volt in this example). If you run 10 amps through that connection (note that a 60 watt headlight draws 5 amps by itself), watts dissipated is 10 times 10 times 1/100 = 1 watt. More than enough to cook a connector.
So if you have a cooked connector, especially in a high current area like the charging circuit and around the battery, make sure you look at both sides. Could be something blown that is drawing much more current than it should. Could also be a bad connection that is restricting the flow of current and baking itself in the process.

 

[buster]

Well I guess my question then becomes "What's upstream?" From the Rectifier where does the electricity go next...

I am not a electrical guru of any sorts so this all gets confusing for me.

Is the rectifier what is known as the regulator or is that a different part? Is it allowing more current to pass through than it should?

With everything that you said, even if I replace the connectors where do I start checking from there. I don't know that i want to solder wires together and moving the problem down stream. I think that I would rather replace the connector and have it melt again than burn up something in the engine itself. Does that make sense?

 

[Nessism]

The factory R/R is grounded very poorly - to the battery box with rubber mounted grommets. When, not if, this ground corrodes and increases in resistance it causes the R/R to overheat - which often takes out the stator. Standard procedure is to extend the R/R ground and run it directly to the battery. I'm not 100% sure this is the root cause for the problem in question but I'm 100% sure you should improve the ground before something like this happens again.

 

[tomm]

The charging system (rotor/stator, rectifier and regulator) provide electricity to the bike when the engine is running, and also keeps the battery fully charged. The battery provides electricity when the bike is not running (like for starting), and also when the bike is at idle and the charging system might not be generating enough output.
But bottom line, when the bike is running, whatever current the bike is drawing, 10 amps, 20 amps, whatever, is coming out of the rectifier. (The stator provides the rectifier with AC current to be converted to DC current, and the regulator siphons off any excess.)
For this to work correctly, the output of the rectifier and the input to the regulator need to be connected to battery positive. Those would usually be red wires. And battery negative needs to be connected to rectifier ground and regulator ground. Those would usually be black wires. Current to everything else on the bike then flows between these two points . . . battery negative / ground to battery positive / rectifier output. And for that to work, the battery negative / ground needs to be connected to the engine / frame.

Best way to think of it is that current has to flow, and should only be "slowed down" by whatever it is trying to power, like lights, coil, etc. Anything else that gets in the way, bad connections, wire that is too small for the current it is carrying, etc is a problem.

I'd start with cleaning all those connections first between the battery, R/R and engine/frame. And add that direct ground as Nessism indicated. The stock wiring uses the frame a lot to make ground connections back to battery negative, and these definitely corrode over time. My guess is that your overheated connector is somewhere in that circuit as well. I'm thinking the connection between rectifier output and battery positive is most likely.

If that doesn't fix the problem, we can work from there, but next steps would be going through the stator paper diagnostics to see if something there is shorted out, like one of the rectifier diodes, or the regulator. Last steps would be looking for a short somewhere else in the bike wiring (highly unlikely, as you ought to be blowing fuses left and right if that were the case).