Alternator not charging

I got a Standard brand regulator. I also have a good Craftsman voltmeter.
So in this situation I put the voltmeter on and check the volts from the battery. I continue right there checking the volts and have the wife crank it over and start it and notice how much it drops while cranking? Then of course what it's doing while it's running? Did it go up did it go down did it stay where it was at?