A vehicle AC generator apparatus includes one or more rectifier elements
for rectifying a generated AC voltage, and a generator control apparatus
which monitors the voltage difference between opposing terminals of a
rectifier element, to thereby detect the commencement of electrical
generation upon engine starting as the time point at which the polarity
of the voltage difference first corresponds to the forward conduction
direction of the rectifier element. Controlled parameters such as the
current supplied to a charging warning lamp and the excitation current of
a generator winding are changed appropriately when generation
commencement is detected.