What's the correct method for testing an external voltage regulator. The amp gauge on my '68 shows a constant 20-30 amp discharge when the headlight are on and the battery will discharge to the point that i have hardly any headlights in a very short period, along with the fact that the car won't start without being jumped, pushed or the battery recharged. Obviously, the charging system is not working properly and i want to check the regulator when I have the alternator tested. I haven't fooled with an external regulator since i had problems with one on my '61 chevy back in 1967 when i was in high school. Yeah, yeah I know. That makes me an old codger.

 

The tests for the voltage regulator involves a meter, variable resistor and a few jumper wires. It is in the shop manual, 2 pages long. For a $10 dollar part, I would buy a new one when you have your alternator tested. Call me lazy....

 

Big_G,
Thank's for the reply. I found the tests for the entire charging system, along with the wiring diagram, in the chassis service manual last night. Already have a new regulator. I just want to check out the entire charging system. As I mentioned before, I have an issue with a significant discharge of the battery when the lights are on. I discovered last night that (1) the fusible link section of the wire from the "Bat" connection on the alternator to the regulator is extremely brittle and has been covered with electrical tape and (2) a section of the windings of the stator in the alternator are black and "sooty". The insulating varnish on the this section of windings has obviously gotten quite hot. I tend to be more concerned about the "burnt" fusible link.
Didn't get much time last night to work on the car, but here are the "symtoms" at present. Battery took and held overnight, a full charge, after 6 hours on a trickle charger. Car stared normally. Ampmeter slows a very slight discharge with engine at idle and no load on the charging system such as lights, blower motor, etc. (As a side note this car has a really "nasty" cam, and i noticed that the idle is set at only 500 RPM. I need to bump the idle up a bit....). When I raise the idle speed by depressing the gas peddle, the ampmeter will show a charge, the amount of which being dependent on the idle speed of the engine, although it always seems to level out around 20 amps.. With the engine at normal idle, turning on the turn signals will cause a slight discharge when the signals blink. Turning on the headlights with the engine at idle will cause an approximate 20 amp discharge. Again, raising the idle of the engine will cause the ampmeter to display a charge. I really am leaning towards a bad alternator. But that brittle, taped fusible link really bothers me.........

Anyone, comments or suggestions?

 

Fix the fuse link with the appropriate gauge link wire, and raise the idle speed to at least 750 rpm. You should always show a charge regardless of load above 1000 rpm's. If not, the reg. and regulator need to be replaced, especially since you said you saw burned insulation on the stator windings in the alternator.

 

Thanks, Big_G. I'm gonna' go ahead and replace the regulator and alternator (I'll have old alternator rewound and put it on the shelf, as it's correctly date coded for the car). The service manual calls for a 20 gauge orange wire fusible link at the #3 terminal of the regulator. Hmmm...I could swear that the one there now is a 14 gauge brown one, which would be the same as the one at the solenoid battery terminal? I believe I'll be installing the one GM originally called for.