Alternator whistle sound
Might be a bad diode, or two. Alternators generate three phase AC, and use 6 diodes to rectify. Loss of a diode, reduces power output, and makes the output bumpy, hence noise and strobe.
The green line in bottom trace is correct DC waveform, the battery filters, and makes it a straight line. Imagine loss of the red #2 phase, the green would then only follow the black and blue, resulting in significant dips, where red peaks. The regulator does not fix, it actually makes it worse. When the regulator sees the dip, it increases field, but that is not enough, then when blue phase is encountered, the voltage spikes high, before regulator compensates.
Might be a bad diode, or two. Alternators generate three phase AC, and use 6 diodes to rectify. Loss of a diode, reduces power output, and makes the output bumpy, hence noise and strobe.
The green line in bottom trace is correct DC waveform, the battery filters, and makes it a straight line. Imagine loss of the red #2 phase, the green would then only follow the black and blue, resulting in significant dips, where red peaks. The regulator does not fix, it actually makes it worse. When the regulator sees the dip, it increases field, but that is not enough, then when blue phase is encountered, the voltage spikes high, before regulator compensates.
