RonKZ650 wrote: All I know about the subject is a 1978 KZ650 with factory reg/rectifier will not regulate without a battery there as a load. I found this out years ago when a battery terminal broke off my battery. I was riding along and noticed my turn signals would no longer flash, then noticed my headlight was burned out. I burned every single bulb that was illuminated. The volts went up to stratosphere. Don't know how high, but it cost me a headlight and at least 15 other bulbs. So if you do go batteryless be sure you know it won't burn up other things.
Yes, that is true, but as long as a capacitor is there, the regulator should work ok. But it is worth mentioning that you really want to make sure you have a good, reliable capacitor, or you can run into trouble.
The battery doesn't need to act as a load, but it does need to smooth the pulses. The regulator is designed to regulate the
average voltage. But if the voltage is in pulses, the
RMS voltage will be too high and cook everything.
When you lose the battery or capacitor, the DC voltage has a huge AC component due to the pulsing. The AC component contributes a much higher RMS voltage. With smooth DC, the RMS voltage is close to, or exactly, the same as the average voltage.
It's much more difficult to regulate or even measure RMS voltage, and bikes usually only need to deal with average voltage. RMS is the true measure of the energy carrying capacity of a signal. But with pure DC, the average voltage and RMS voltage are the same, so regulators usually regulate average voltage. It's only when the signal has large fluctuations that the RMS and average values diverge.