alternator

my alternator keeps failing ?car runs of batt ,then kills batt,

Hi.Did you replace the alternator??. Did you get a junkyard part or a reman alternator? More info please.Diesel1962

Year of vehicle also.

i had same problem on my 98 deville. The message on dash read "BATTERY NOT CHARGING" and car would do the same thing you described. It turned out to be the voltage regulator. On mine, it is built right into the alternator. The guy who rebuilt mine first used a foreign regulator and that blew out in two weeks. He then installed one from dealer and no problem now. I chose to have my OEM alternator rebuilt and amperage upgraded from 140 to 240 amps instead of buying a remanufactured one. They also replaced diodes, stator and brushes. The price was about the same ($220.00) as a reman and I been hearing some bad reports about some of them. cadillacowners.com site gave me a lot of knowledge about this problem. I had the guy increase the amps because I put an 1800 watt monoblock amplifier and two sealed 12inch subs in and it eventually began cutting out and dimming lights and ultimately burned out the voltage regulator. Now that joint kicks out some serious ass bass and lights don't dim anymore and car even seems to start up quicker. these fools here didn't even reply when I asked for some help in removing the alternator last month. They must not know much about cadillacs. I like this site anyone despite the apparent absence of tutorial introspection alloted sofisticated motor vehicles designated cadillac, present company excluded.