[Shotimes] Semi-OT: '95 SLO Charging system

[Jon Heese]

Just an update on the charging system problem in my '95 Vulcan SLO:

WARNING: DON'T TRUST AUTOZONE'S ALTERNATOR TESTER

It incorrectly concluded that my bad alternator was good and cost me a 
day of troubleshooting by my assuming the results were accurate.

One thing I noticed: The AZ alt tester tests the alternator in 3 phases, 
noting on the display screen which test is running at the given moment. 
  In order, the 3 phases are "Alternator Test" (I assume this is where 
mine would've failed), "Rectifier Test", "Regulator Test".  The first 
phase runs for maybe 3-5 seconds, and the remaining phases run for the 
balance of the ~30 second test.

Now, when I'd start the car, it would appear to charge the battery 
properly for the first few seconds (which was right when the alt tester 
was testing the output) and then it would quit charging and the system 
voltage would start dropping.  It is my theory that the reason why the 
tester cleared my alternator as "GOOD" was because the "Alternator" 
phase of the test was too short.

I ended up taking it down to my mechanic friend who ran through the 
Service Manual diagnostic tests and concluded the alt was bad.  I 
replaced it with a brand new Bosch unit ($150 after my "friend" 
discount) and after more than a week, I've had no problems with the 
charging system and it's measuring an even 14V while running.

Thanks again to everyone who helped out with suggestions.

Regards,
Jon Heese

Jon Heese wrote:
 > After the last voltmeter test showed some raised battery voltage 
while running, I decided to go out and run the car a little bit to see 
if the battery seemed to get stronger or weaker.
 >
 > Results:  After about 2 minutes holding it around 1500 RPM, the dash 
lights started to dim, turning on the headlights noticeably dimmed 
everything even more, the car started running a little rougher than 
normal, and interestingly, as I turned the headlight switch from off to 
the parking lights, to headlights on, the tach jumped a couple hundred 
RPM.  Not the engine, just the tach.  Also, it seemed like the tach 
refused to drop below 1000 RPM, even when I let it idle (~750 RPM).
 >
 > I'm thinking there's definitely something funny going on with a 
ground somewhere...  Any ideas of places to check?
 >
 > Regards,
 > Jon Heese