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

[Brett_jjj]

As hako said,take a spare battery so you dont get stuck on the side of the highway.The screws might have to be undone with an impact driver.You can try hitting the screwdriver handle on the end with a hammer as you try to turn it.Its similar to what an impact driver does.

[wamboin23]

tip no 1 - there not phillips head, there pozi-drive. get a pozi-drive. (all the screws on a bosch alternator, starter are pozi-drive. you can tell them apart from a standard phillips head, by the straight cut teeth, and the extra small teeth in between each normal tooth)

tip no 2 - give the head of the screw a good hit with a punch, or with the screw-driver itself, to try and break the hold of the thread.

tip no 3 - don't strip out the head of the screw.

[-=$natch=-]

Well I'm finally back home after my trip, managed to make it without any issues. And would you believe that the battery light NEVER came on, and then the day after I got home the battery light came on when I drove up to the local corner shop...wtf is with that?? Hasn't done it at all today either...got me stuffed what the problem is!

[Brett_jjj]

It definitely sounds like a bad connection somewhere.All you can do is keep looking until you find it ,or take it to an auto electrician.

[woteva]

Have you changed the regulator thingy on the back of the altenator ??

[ephect]

i'd say the brushes are worn.. a car of this age they are bound to be at the end of there life.

you can change them yourself if u buy the brushes

[-=$natch=-]

i'd say the brushes are worn.. a car of this age they are bound to be at the end of there life.

you can change them yourself if u buy the brushes

The old brushes were still pretty good, but I replaced them anyway when the light first started to appear. Didn't help. I've also tried another alternator which seems to have the same intermittant problem. So as others have suggested, I'll have to keep looking at the wiring to see if or what the fault is.

[ephect]

sorry bud, i re-read ur first post! DOH!

maybe a hot earth kit will rectify any bad wiring.. essentially rewiring the earths.. do you have any power cables spare from an audio install that you can use to replace any wiring that may look suspect?

[mollyvs]

hi u need to replace the volteg regulator on the back of the alternater only $40 from ashdons

[mollyvs]

hi spelling not to good it is ashdowns

[-=$natch=-]

Which bit is the voltage regulator? Is it the black bit that unscrews, that the brushes are soldered into or is it the bit inside the alternator at the back?

[woteva]

The black bit that unscrews with the brushes needs replacing, if you havn't already done it.

[nathg]

It is black, and has two screws, you kinda twist it out of the back of the alternator. That is most likely the source of your problem. People need to realise that this should be the first thing changed, not the alternator, because it is so much cheaper lol

[WAGON MAN]

Which bit is the voltage regulator? Is it the black bit that unscrews, that the brushes are soldered into or is it the bit inside the alternator at the back?

Fixing alternator

[-=$natch=-]

I can't seem to find any pictures or anything on that link sorry..??