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

[Jon Heese]

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

Jon Heese wrote:
> Man, I'm just not having good luck with my cars today.  I just posted 
> about my '95 ATX with the fuel delivery problem, and now my '95 Vulcan 
> SLO has decided to stop charging the battery...
> 
> While the car is running I had funky radio "skipping" when I turned the 
> headlights on and the dash lights were way too dim (the dash clock was 
> very dim and faded out from left to right).  So I charge the battery 
> with jumper cables from my dad's truck.  After removing the cables, the 
> dash lights/radio are back to normal.  Voltmeter on the battery says 
> 12.52V (engine off).  Low, but it's not been charging long, so not a 
> very good test.
> 
> Start the car, voltmeter on the battery says 12.15V.  Great, so it's 
> definitely not receiving any charge from the alternator.
> 
> So I pulled the alternator and took it to AZ (apparently it's illegal 
> for them to test it on the car in my county, go figure) and it passed 
> all three tests (alternator, rectifier, regulator).  Okay, pop the alt 
> back in.
> 
> Next, I checked the battery with a load tester: showed ~11-12V under 
> load, which is in the green area of the tester (it's only about 2 years 
> old).  Okay, so it's not the battery.
> 
> Interestingly, after putting the alternator back in and letting it run 
> for a minute or two then shutting it off, the battery reads 12.29V. 
> While idling, it shows 12.50V, goosing the throttle jumps it to ~12.75. 
>  So now it *is* charging, just not very much.  Maybe I knocked some crap 
> loose on the alt connections?
> 
> So I test resistance from the pos battery terminal to the big alternator 
> cable terminal: ~4 ohms.  Resistance from the battery pos terminal to 
> the megafuse is also ~4 ohms (as a reference, my meter shows ~0.3 ohms 
> touching the probes together).  Seems like the alt cable resistance is a 
> bit high, but it's not like I can just swap it out, it's all in the 
> wiring harness...
> 
> Ideas?  Thoughts?  Anyone?
> 
> Regards,
> Jon Heese
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