Alternator Voltage?

Hey guys i have a 71 demon with hei ignition and with the engine off i read about 12.5 volts at the battery. but with the engine running when i measure the voltage at the battery terminal on the alt. it reads about 11.4 volts, also my ammeter shows about -5 to -10 is the alternator under charging? or am i measuring the alt voltage at the wrong place?

Any help is greatly appreciated.
:prayer: