wires to brushes gives fields to create ALTERNATED CURRENT ( hence the alternator name ) by sine waves produced by the + and - fluctuations when rotor spins, creating magnetic fields what stator captures. Then Diodes hooked up to stator take care of take the correct polarity of the waves to stud and chassis, becoming on DC ( direct current )

since we are talking about - and + fluctuations on sine wave, doens't really matter what happens first on the sine wave, if - or + section of the wave.

With a Charger born in Chrysler assembly plant in Valencia, Venezuela