How can I check if my Audi 80's alternator needs to be replaced?

I have been experiencing some issues with my Audi 80's battery and I suspect it may be due to a faulty alternator. How can I diagnose and confirm if this is the case?

The first step is to check the battery voltage with a multimeter. A reading of less than 12.6 volts is a sign that the alternator is not charging the battery properly.

Another way to confirm a faulty alternator is to start the car's engine and remove the negative battery cable while the engine is running. If the engine shuts off, it means the alternator is not generating enough power to keep the engine running.