Charging System Issues
FINAL UPDATE (11/27/12)
The saga has ended at last. If you want to see what the problem was and how it was solved, jump directly to Post #59 in this thread. Many thanks to all who participated in this thread especially Slimvulcanrider.
END OF UPDATE
IMPORTANT UPDATE (7/18/12)
To anyone who has participated in this thread (or wishes to do so), please go directly to Post #23 and read it thoroughly before posting your Reply. If, after reading that Post, you think you need more information, then go ahead and read as much of the thread as you want to. You will probably find what you need in it. Thank you all.
END OF UPDATE
CORRECTION: Read this first
By the way, I did find a flaw in my most recent testing. I thought I had good readings from the RR ground to the battery negative post and from the RR hot lead to the positive battery post. I was in error. From the RR ground to the post, I get .6V and from the hot lead to the post I get a highly variable reading between .15 and .3V. ElectroSport's flowchart indicates both readings should be no higher than .2V. So it would seem I do have a bad connection, probably on the ground side, but I was unable to locate any such connection the first time I went through the wiring harness. I did get some seemingly bad resistance readings, but eventually they went away and it seemed I had good continuity and good charging voltage at the battery post (14V or greater) before I put everything back together the first time. Can anyone tell me the best way to check for a bad connection? Nothing seems fused; loose; arced or corroded.
END OF CORRECTION
I bought a used 1990 Vulcan 750 recently. There is a problem in the electrical system that seems to appear as a charging problem. There is much helpful information on the forum which I have already reviewed and tried to apply, but it seems as if I am just running around in circles. Perhaps someone can get me pointed in the right direction when I describe my symptoms.
Voltages off the stator seem good. I get in excess of 70 volts on all three yellow wires at 4000rpm. I have a new RR since I first suspected that was the culprit. I also have a brand new battery since I suspected it next. I did the ElectroSport flowchart tests that suggested a bad connection on the ground side of the RR output. I explored that possibility by unbinding the harness and checking for bad connections through the wiring and back to the battery. I did not find any obviously bad connections, but apparently I did something to eliminate the bad connection because after rebundling the harness, the bad voltage reading disappeared, and I had good charging voltage at the battery terminals (13.5V at idle 14+ at higher Rpms). I breathed a sigh of relief and thought my problems were over.
Next morning I tried to start the bike. Battery was almost completely dead! (It had been fully charged the day before.) Jumped the bike and got good charging voltage but did not ride. I took the battery out and put it on trickle charge overnight. I installed the battery after full charge. Started the bike and it fired right up. I then stopped the engine and disconnected the battery and let it sit overnight. This was just an attempt to rule out a bad battery. The next morning I reconnected the battery and the bike started fine.
Before starting, I did put my DMM in line with the battery at the battery negative post to check for any current leakage. None was detected. With the bike running, the charging voltage at the battery posts is now less than 13V even at high rpms. Stator voltages are still good. There is no indication of the old fault on the ground side of the RR. However, with the bike at idle, I pulled the connector at the RR off. When I did this, the rpms ramped up by about 400-500 rpms. I stopped the bike and walked away for about 30-45 minutes. When I came back to start the bike again and explore further, the battery was dead! No, I did not leave the ignition switch on!
I am not an electrician or a mechanic, but I do have some limited skills in both areas. I cannot imagine what would drain the battery so quickly, and I do not know if the jump in rmps with the removal of the RR connector is normal.
Can anyone suggest a reasonable manner in which to proceed with the symptoms I have described? Is this likely a junction box issue or some other issue independent of the charging system? The battery won't be fully charged now until tomorrow, at which point I would like to see if I can track down the problem or problems. Any guidance would be GREATLY appreciated. Thanks.
Last edited by gvaughn111; 11-26-2012 at 04:38 PM.