Electrical charging system question, Alternator? Options

[rjames]

I installed a brand new battery and a new voltage regulater last week in the car. My volt meter is showing 12.5 volts at the terminals. With the car running and the lights and fan on my volt meter fluctuates between 12.7 and 12.9, then slowly starts to dip, getting as low as 12.5 before I decided to shut the engine off because I could see that the battery was slowly draining.

Would it be logical that the alternator might need replacing? The alt. belt also seemed tight (not sure exactly how tight it should feel though.) I can check the electrical connections (have to find them first though.) The connections at the battery all look good though.

It doesn't look like a fun job to replace the alternator, but I'm up for the challenge. Anything else I should look for before I go this route??

Thanks!

PS: Forgot to add that the alternator light on the dash comes on when starting the car, but goes off right away once it's started and doesn't come back on at all when driving.

[rjames]

I just got done reading the Pelican article regarding troubleshooting the charging system:

http://www.pelicanparts.com/techarticles/9...roubleshoot.htm


After reading this it would seem that as long as the right bulb is installed for the alternator light then any charging problems should light the bulb. My charging light goes on when turning the key to the on position, but after the car starts it goes off right away, and does not come on at all when driving. I suppose this doesn't really change how I should test things, but wonder if it points to something specific (other then, hey- there's something wrong with my charging system!)

In looking at the article, there are 2 tests I should peform and of course I have questions about both as I have limited experience with electrical issues and don't want to die or get shocked, or ruin my car while testing.

TEST 1)Connect +12 volts from the battery to the DF terminal on the relay board.

So with car running I connect run a wire from the positive post on the battery to the DF terminal on the relay board. Is the voltage regulator still plugged in for this test? Is there specific cable guage I should use for this test?

TEST 2) To check the D+ portion of the system, it is necessary to find out if the D+ output can produce enough current to drive the alternator to full output. To do this, short the D+ and DF terminals on the relay board. This will provide the maximum field current to the alternator that the alternator ITSELF can supply (not the battery, as in the earlier check) and so checks the remainder of the circuitry. If this test puts the light out, then the alternator is good, and the trouble is elsewhere.

Should this test be done with or without the VR installed?


Again, be patient w/me as I haven't worked much with electricity in this capacity. I learned how to weld and fixed the longs on the car this year just from reading posts on this board so I'm sure I can learn to troubleshoot this stuff as well. I just needs some guidance.



One more idea, could my charging woes be from a slipping belt? I don't hear any noise that would indicate it. Is there a way to test if the belt is slipping? (Other then sticking my fingers back there...)

As always, thanks everyone for the help- if nothing else it will enable me to help someone else out at some point in time.