Cadillac Repair: Charging System, cadillac eldorado, autopart store

Question
Hello- I have a 1998 Cadillac Eldorado. Had a system display read Service Charging System & Battery Not Charging. Watched battery voltage decrease from 14.0 to 11.4. The battery was checked at an autopart store, was told need replacement. Did that 2 days later same displays & voltage decrease. Alternator was replaced. 1st day battery volts read 14.4 at start and dropped to 18.6 while driving. Was told normal. 2nd day started at 13.8 and dropped to 13.3. Was told below 13.5 is indication of alternator not outing sufficient power (amps?)however no display regarding charging system or battery (yet)but I want to prepare. What else might it bad? Electrical?

Answer
Alternator was replaced. 1st day battery volts read 14.4 at start and dropped to 18.6 while driving.

18.6 ?

Is the alternator HOT to the touch when engine is at normal operating temp ?. It should be.

This is most likely normal as the battery is most likely highly under charged. try charging the battery with an external battery charger for a few hours and if you get the same results, Have the battery tested.

Normal range at 2000 rpm's of the enginme is 13.8 to 14.2 volts.