Battery Light on and the Battery is fine but will not keep charge

RECHECK the New Alternator This is Not Unheard of as I Have Experienced it Myself Several times.
After RULING it out and the Fallowing,Main relay box Power terminals, Corroded Loose fit nuts Etc.
Consider Voltage Regulator, Read the fallowing "CAREFULLY"

CIRCUIT OPERATION
The Electronic Voltage Regulator (EVR) is not a separate component. It is actually a Voltage regulating circuit located within the Powertrain Control Module (PCM) . The EVR is not serviced separately. If replacement is necessary, the PCM must be replaced.

Operation: The amount of DC current produced by the generator is controlled by EVR circuitry contained within the PCM. This circuitry is connected in series with the generators second rotor field terminal and its ground.

Voltage is regulated by cycling the ground path to control the strength of the rotor magnetic field. The EVR circuitry monitors system line Voltage and battery temperature (refer to Battery Temperature Sensor for more information). It then compensates and regulates generator current output accordingly. Also see Charging System Operation for additional information.

FOR Detailed Diagrams,on Entire Charging system they Must be Emailed,as they are too Large for the Formatting that "FixYA" uses my Email add. is My nickname here but add @aol.com By all Means If this is of Help to you , Then PLEASE RATS Me Thank you and have a Blessed DAY rejakwilson