Voltage Regulation During Flight
I recorded the voltage during a "typical" 45-minute flight in my M20C. The DVM recorded 2 samples per second; there are just over 5000 points in the first graph.
Overall comments
The generator is only "on line" when the engine is running >1600 RPM or so
The voltage is noisy even in steady state conditions
The voltage of the bus depends strongly on the applied load
If you look closely -- see the "First 5 Minutes" expanded graph -- you can see the mag checks which reduced the RPM from 1700 by about 100 RPM and the voltage about 1/2 volt. After run-up, back to 1000 RPM and the voltage fell back to ~ 12 V.
During flight I turned on various loads -- for example, at 15:44 local time I turned on the landing light (250W) and the voltage dropped. At 15:49 I turned the landing light off and the voltage increased again.
Background Information
Voltage was measured at the radio master bus
The plane has original-type 50A generator
It has an original-style mechanical voltage regulator
I notice that the battery appears to be reaching full charge only near the end of 45 minutes of flight -- fully charged is a voltage of about 2.35 volts per cell for a lead-acid battery, or 14.1 volts.
Does anyone think that changing to the newer solid-state type generator regulator (Zeftronics, for example) will improve this situation and reduce the noise "hash" seen here?
