It is true that there are shunt type voltage regulators. But a shunt type can not
possibly be used with the Rotax iS. The Rotax iS generator output is rated at 420 watts.
A shunt type would need to be capable of dissipating 400 watts of heat. How is
that possible when the regulator is not much bigger than a pack of cigarettes?
The regulator is rated at 80 degrees C. If it had to dissipate 400 watts, it would
get as hot as a milk house heater. Why would Rotax design the voltage regulator
with old shunt technology instead of the new switching type? Well, they didn't.
The smaller the electrical load is, the cooler the regulator will be.
The voltage regulator does not care if the landing lights are on or not.