Alternator or Battery?

[YADA]

About a week ago my battery light started coming on at around 3000 rpm but would turn off as the revs dropped. It gradually got to where it would come on every time I accelerated and would take a few seconds to turn off after starting the engine and idling.

My wife just took it out and she rang for me to go pick her up. The engine light was on and the fuel and temp gauges were dead. So was the battery. I swapped the battery for one out of our other car and drove the VS home. The battery light came on dimly but gradually faded to almost nothing by the time I got home. It still came on if I gave it a good rev. I've got the old battery on charge.

The car is a standard VS Executive Wagon with about 270,000 Km.

Any ideas on whether the battery has had it or if the alternator is done for?

About a week ago (would you believe it) I left the hatch up and the rear interior light was on for about 36 hours. The car still started o.k. though.

[betts]

I would say alternator. It doesn't sound like its charging properly, if at all. A similar thing happened to me a while ago, but the battery light was on all the time. My alternator had chucked it in, and eventually the battery went flat.

[YADA]

I think you're right. I just went out to it with volt meter to see if the alternator was charging and it won't start... The battery from the other car was only in it for the half hour drive home and an hour or so in the driveway.

They're not too difficult to replace? Just take the old one off and bolt the new one on?

[chrisdoesitbetter]

a cheaper fix is to try replacing the regulator/brush assembly it has an electrical clip on top and it screws out cost about $60

[betts]

Well yes they are relatively cheap to fix yourself, the reason most alternators crap themselves is because the rectifier packs it in. You can pick up a new one from dick smiths or something like that for next to nothing, take it to an auto electrician and they will charge you over $100 for it. If you are alright with electronics and stuff then pull your alternator out and just get yourself a new rectifier.