Quote:
Originally Posted by kamocat
Don't forget about the capacitor. The input should be somewhat smoother than the output.
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Marshall,
The cap will take away some of the voltage fluctuations as the controller supplies current to the motor. The majority of the motor current comes from the battery. If you think in terms of impedance and where the current is flowing, it might help. The battery is a nearly infinite supply of current (compared to the cap in the controller) at a relatively low impedance, about .011 ohms. When you add in the controller, the cap now sits across the battery as a load. There is a small shot of current as the cap charges but then it simply idles at the current of the controller. When you turn on the motor, it is now in parallel with the cap. The cap will supply some current but the battery supplies the majority. However, there is the series resistance of the wiring. As this resistance increases (small wire, poor crimps, etc), some voltage drop will occur at the input to the controller. The cap is designed to supply current to the electronics to keep that voltage drop from affecting the regulators on board the controller.
DC and true RMS are the same. 12 volts AC
RMS is 34 volts peak to peak or 17 volts peak. Please be sure to check your meters, most are calibrated to make an equivalent RMS reading on 60 Hz, sinusoidal voltages only. Change the frequency or the waveform and the meter will lie to you.