Part of the reason I have not been around for a while is I don't drive the Lolvo much at the moment (mainly as I can't afford to).

Recently I have been having flat battery issues which I put down to the lack of use. After a jump start from a spare it would be happy again.

Yesterday where the car did not have enough juice to unlock the car and when I opened the door the alarm sounded like a duck being strangled in a large tiled bathroom.
I jumped it and drove to where I needed to be. On completion of the journey it didn't have the power to lock the doors again. That should have been a clue but I assumed the battery was a gonner.

Today I swapped over the battery for the spare I had been using. Everything was smiley.
I put a multimeter on it and at idle it said 13.7v and it went up a little on revs.
I drove off on a long journey and after about 30 miles the battery light came on the dash along with a message about 'charging maintenance' or something. After a spirited rev it went away. A few minutes later I got a warning message saying battery low.
I had to turn round and drive home for fear of being stuck in the wilds of North Yorks. Low batt light on all the way home.

We went out again in a different car and 6 hours later returned home. I tested the car and it starts ok. Voltage is a static 12.1v which means it clearly isn't charging.

So:
1) I reckon alternator; do you concur?
2) are these the same across the range or does a 2002 2.4T have a rare and expensive version?
3) Anyone breaking an S60 and/or has a spare alternator?