How to troubleshoot a weak alternator in an Audi 80?

I've noticed that my Audi 80's battery is constantly dying and I suspect it's due to a weak alternator. How can I troubleshoot and fix this issue?

First, check the alternator's belt for wear and tightness. If it's loose or worn out, replace it. Then, check the alternator's voltage output using a multimeter. It should be around 13-14 volts. If not, replace the alternator. Also, make sure the battery terminals are clean and tight.