Cadillac Eldorado Alternator Not Charging

I Have Intermittent Charging Issues On My 99 Eldorado Xtc. Twice In Three Months I Have Found The Battery Completely Dead For No Reason....

I Have A 99 Eldorado Etc With 117k On It. I Had The Head Gasket Repaired And Now I Have A Short. I Replaced The Alternator And Battery...

Message Center Will Indicate "battery Not Charging" When I Start The Car In The A.m. After Driving A Few Minutes, The Alternator Kicks In...

Cadillac Eldorado 1998 81,000 Miles 4.3 Literv8 Computer Message--battery Not Charging Then Computer Message 13.8volts And Then Voltage...