the battery is definetely good. im a nissan technician (yeah i know its not
audi but electrical is electrical) and a steady volt drop of 12.6 at idle is
perfect!! usually 12.4v drop across the battery is what youll find. and
youre charging volts are almost perfect as well. 14v-14.4v is what you want.
id definetely say something is making contact. however, if the bearings in
the altenatore were going/gone, id ont think your charging voltage would be
so good, or at least not as steady.
check with a DVOM (voltometre) and see if the charging volts really ar 14v.
sometimes thos factory gauges lie a bit. if its below 14v, then id say your
alt is on its way out and should be replaced. are you having ANY electrical
load issues? like dash lights or headlights are more dim than normal, etc.?