you may want to check the brushes that are part of the regulator on the back
of the alternator. they sometimes wear down to the point that they make no
contact, no charging and (worse) no light to tell you what's going on.
It can be a little hard to check, but look at the "shine" on the contact surface
of the brush or compare the lenght to a new or known good regulator.
your charging light(in instrument cluster)should light when you turn the key
and before you crank.
A tool to buy is an inductive Amp meter. you simply hold it over a wire to check
how many amps flow thru it without disconnecting anything. they are available
in different ranges for starters and alternators..highly recommended.
Hope this helps
JV