Issue with Alternator/Battery light in VR V6

[-=$natch=-]

For the past couple of weeks the battery light has been coming on, then off, then on... it's always random, for example sometimes it will be on when I start the car and go off within a few seconds or a few minutes while other times I can drive the car for a few days without it coming on and then all of a sudden it will come on while I'm half way to work...

I have replaced the brushes which didn't make any difference, I tried a spare alternator that I had lying around from a VP (which I don't know weather it's good or buggered, never used it before) but it did the same thing... When the light comes on the volts on the battery drop to around 12.2 but when the light is off it puts out roughly 14.4 volts. Also from what I can tell, the alternator appears to be in good condition, bearings seem alright...so I'm wondering if it could be a dodgy wire or connection somewhere??

Anyone had a similar issue?? Are there any connections/wires I should look at in particular?

I really can't afford a new alternator before xmas, but I am driving the car from Adelaide to melbourne on Tuesday.... :/

 

[Brett_jjj]

Have a good look at the wires behind the alternator,especially the main single charge wire,this gets corroded under its cover,which causes a bad connection and high resistance.It will cause what you describe .

 

[-=$natch=-]

Yeah I've disconnected that big wire and the other plug on the actual alternator and cleaned them up, both appear to be getting a good connection. I've tried to follow the wire's as far back as I can but can't seem to find anything. Hopefully tomorrow when there's better light I'll be able to go over it a bit better, as my garage lighting is crap.

 

[hako]

Try bending the wire just near the connector - this is where it heats up and the copper cable crystallises and the copper actually will crumble in extreme circumstances. Also check the earths from engine to chassis and chassis to battery negative.
Also check to see if there is any voltage drop between the alternator main cable terminal and the battery positive post....should be no more than 0.1V with engine running.

 

[woteva]

Had the same problem before. Checked the wiring, found no problems. Then replaced the regulator thingy that is in the back of the altenator. It took about 5 minutes to change.

 

[-=$natch=-]

Thanks for the ideas guys, going out now to see what I can find.

 

[-=$natch=-]

Well, I cleaned up all of the battery connections, chasis and engine earth points, checked the wires going to the alternator, cleaned those and their connections up....still have the battery light randomly coming on.... The only part left to inspect/replace is the "rectifier" thingy inside the alternator I reckon...tried to open up the alternator for a look but can't budge any of the four long phillips head screws/bolts. Is there any special way to undo these buggers??

 

[Brett_jjj]

I'd be trying another alternator,try and borrow one you know works.(off a mates car etc)

 

[hako]

Checking the diodes in the rectifier can be done externally but they usually fail completely. I'd follow Brett's advice and try and get another alternator or carry a spare fully charged battery for the trip to Melbourne....driven in daylight hours with the air off the battery should last for at least 8 hours.
Good Luck.

 

[-=$natch=-]

Haven't been able to get hold of a another to test (as I've only just moved to Adelaide and don't know anyone), but have still been driving the car around and the battery light only comes on very occasionaly (say for a minute or two on a half hour drive...etc). I'm really hoping that it's just a loose connnection that isn't gonna cause me any greif for one day of travel, so that when I get to Vic I can grab another alternator off a mate and give it a go. Also, is there any trick to getting the 4 big long phillips head screws undone?? It's like they are welded on!! lol