I replaced my alternator today and car is running fine but still have a couple of worries.

I smell some burnt rubber which i assume is because i didn't put everything back together in the same configuration as before, but I checked the belt after driving for a couple miles and it looks good. Could this be from the new alternator?

Also, alternator doesn't sound like my older one. It makes this weird chattery sound on low idle and sometimes whirrs like its tired.

My best guess is that the belt is not tightened properly. Any suggestions would be much appreciated.