Chevrolet Repair: Charging, battery terminals, charging system

Question
I have a problem with a 94 Lumina with a 3.1.  The problem is that every time you shut it off, you have to jump the battery, but yet the charger reads full charge.  I was told to possibly check something in the vehicle.  I have no idea where to begin though.  

Answer
Hello Joe...ok First let us check the battery. A fully charged battery should have 12.6 volts dc. Once you have the vehicle running, you should have a reading at the battery terminals of 13.8 to 14.2 volts dc. If you do not, we are going to assume your charging system is at fault.The vehicle will run off of the battery alone for a number of hours until the voltage drops below aprox. 11 volts. You may also have a ''short'' which is draining the battery when you are not driving. We can discuss that fix later. Have the battery ''load tested'' and the starter checked for excessive starter draw.  Good luck