What are some of the volvo s60 alternator problems?

The most common problem You're likely to encounter on Your Volvo S60's alternator is going to be the regulator that's inside of Your alternator. When You notice that the battery isn't getting charged, and You narrow it down to the alternator, chances are what's failed is that regulator, as it gets damaged due to extreme weather conditions, such as high temperature and high humidity. You'll see symptoms of this in an early failure indication that the alternator will charge normally when the engine is cold, but when it's gotten up to temp, the alternator's only putting out a low charge. Replacing this isn't going to be cheap: it can cost almost a grand to buy a new alternator for Your vehicle, unless You go with an aftermarket brand, which will be about half that.