Cadillac Repair: help on cahrging system, electrical issues, charging systems

Question
Im facing electrical issues with my sts95.
The electrical guy says that the alternator and the battery are running well, but on the dash, I see that the message battery no charge appear very often and then goes to 13.4, and the suddenly the one that say low voltage and the car shunt down.
what can be wrong?

Answer
Luis,
GM states that a low charge condition is "normal" at times. Specifically, at an idle with some or all electrical accessories on. If that's what your problem is, you're out of luck. Basically, you want to verify that once you set the engine speed at 2500rpm, that the charging system output is correct. Obviously, GM doesn't want to make any claims about the ability of their charging systems to handle their maximum load at or near idle.