Cadillac Repair: 1997 Cadillac Eldorado, cold cranking amps, cadillac eldorado

Question
Mr. Cherniwchan - I recently purchased a battery because my voltage kept declining w/I turned on the air, radio, etc...  But the voltage is still declining.  How many cold cranking amps does my car need/take?  Also, why does the voltage keep decling?  My lights got very dimm last night, it slipped from 14.0 to 12.9 just on my drive home?

Answer
Hi Lisa, Sounds like the alternator is failing and needs to get replaced. The battery size that you need should be at least 770cca and they make batteries that will fit your car that are as high as 1000cca so if you are in a cold winter area then get the highest one at the price you can afford. Here's the way the electrical system works...The battery needs to have enough cca's to start the engine. Then once the engine is running the alternator provides all the amperage that the car needs to run and the battery just provides power to the alternator so it can do that. But should the alternator not be able to produce enough to power  the electrical system then that is when the voltage starts to drop. When that happens usually a diode goes bad or the voltage regulator can't maintain the voltage anymore and then the alternator needs to get rebuilt or replaced. I would have the battery and charging system tested to determine what is at fault. Since the battery was already replaced it should be ok provided the cables are clean and tight. Then the alternator needs to be tested to determine if it is at fault or a wire connected to it is bad. Hope that helps explain things. Bill