Problem: Battery Died

Bubba diags: I charged the battery and started the car. I disconnected the negative battery terminal and the car stopped running.

Conclusion: Charging system is bad.

Question: How do you check if the alternator or Voltage Regulator is the charging problem?

Note: Obviously the regulator is a more cost effective fix, so I want to be able to check for that first.

Any help is greatly appreciated.

JV