I've replaced the alternator. And the battery. I've tested all the fuses I could find. Still no charge to the battery.

I replaced the alternator because of noises and I was not getting a charge to the battery. This problem happened over night.

 

Check the wires at the alternator to make sure there are good connections and no breaks in the wires.

 

What is it? Does it have an external voltage regulator?

 

yes...what year, engine, make and model. some alternators are ecm controlled.