if you have a voltmeter test the battery while the engines running. should be putting out 13-14 volts. if not alternator stuffed.

turn on lights when engine running, rev engine, if lights brighten when revs up then battery is stuffed.

also, is the charge light on but very dim as opposed to not lit.????? that's a sign of alternator stuffed.

could be the brush assmebly

either way. if the alternator is stuffed most likely the battery will be soon also.

no i am not an autoelec. am son of one. could have also embarrassed said father with my above diagnostics.

Richiefish said...

definately no charge to batt. no charge light at all, ever.( not dim). If the alternator is faulty wouldnt the charge light still come on and stay on ???

how do you know the alternator is not charging battery.?

could be a problem with the dash light. maybe.....

i remember a dark and stormy night when nebbian rescued me from roadside electrical troubles.

Richiefish said...

First thing I did was test it with a multimeter. 12.2 volts with motor running. 12.6 with motor off !!! what I'm up in the air about is this exciter circuit(ign light) thingo.
Why doesnt it (the light)come on when key turned to ign (all other warning lights on). motor is not running at this point so does alternator output make any difference.????

I think as Nebbian said, the charge light is connected at one end to the battery positive and the other is connected (sort of) to the output of the alternator. When the alternator is not providing any voltage there is enough resistance through the alternators output connection to light up the charge light. Once the alternator is producing sufficient voltage, there is no longer any potential between the alternators output and the battery and thus the light goes out.

If this wire was broken you would end up with the light never working, which may be the situation for you. Of course the charge light bulb could also be blown... I think my dim dark memory was suggesting some older cars needed this light to work in order to produce any current. Maybe not such a good memory to trust though.

What ever you do, don't get onto the aus.cars forum and ask this question :)

The voltages you are seeing while the engine is running versus off suggest that there is no charge, so you may as well start with the charge light problem. Check that it lights up when the other end is earthed (the 'extra' connection at the alternator) and go from there.

Gestalt said...

i remember a dark and stormy night when nebbian rescued me from roadside electrical troubles.

That was a very dark and stormy night Gestalt, guess which fluoro light I'm now in the process of fixing? Great weekend though.


Richie, here's some info of what you're up against:
alternatorparts.com/understanding-alternators.html

From what I can gather if your warning lamp is blown, then you won't get any battery charging happening. It's easier to check things at the alternator though, rather than trying to get a tiny little globe out of the dash...

nebbian said...

Gestalt said...

i remember a dark and stormy night when nebbian rescued me from roadside electrical troubles.

That was a very dark and stormy night Gestalt, guess which fluoro light I'm now in the process of fixing? Great weekend though.

youy certainly had a sweet setup.