I changed the alternater 8 months ago and it squeeked from day 1. I endured the squeeking until the other day when it suddenly stopped. One major problem, now I drove my car to the gas station, put gas in, went to start it again and it wouldn't start. My husband came and jumped it. I then headed to my destination which was about 20 miles, round-trip. I parked the 96 Lincoln Mark VIII, went out the following day and she was so close to dead that the security beep sounded faint. Needless to say, she wouldn't start. I was so happy about the squeeking being gone and now I just want it back!
Sounds like the charging system isn't working but this could also be due to a defective battery. Use an inexpensive digital voltmeter to measure battery voltage first before starting the engine and again when the engine is running. A fully charged good battery will measure near 12.6 volts. If you find closer to 11 volts or less, suspect the battery. With the engine running you must find between 13.75 and 14.75 volts. If it is low you will need to measure the voltages on the wires on the back of the generator.