2006 Ford Taurus Check Charging System?

I don't know much about cars. But… Over the winter my cars Check Charging System light came on. But it went off about a minute later. I figured it was just the negative temps that was messing with something because once it warmed up it stopped coming on. But yesterday my car starting making a screeching noise and the Check Charging System light came on again. So I started making my way home and then my car died. I got a jump and made it home but I could tell it was getting ready to die again because my digital dashboard was going in and out and my windows were rolling up slowly. I had someone check my serpentine belt since it was making a screeching noise but the belts fine. Im going to have my alternator tested today, but I don't see why it would making a screeching noise if my alternator is going bad I would think it has something to do with a belt… So I was wondering if anyone else has had this issue and if they had it fixed. I looked it up and it seems to be a common issue in Ford Taurus (I should have listened when everyone told me not to get a Ford:P) But my cars been good to me so far. This is the first issue ive had with it. Thanks in advance.

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