Quote Originally Posted by Slyfox View Post
scott. one thing you need to know about the rotax regulator. they do not like to be shut off when the engine is running. do not, I repeat do not check the alternator like we were taught in flight school. just look at your voltages and say, yup it's working. turning off the field for the alternator will kill the regulator. take care.
Iíve been looking through th deep dark places to find information on this. One source says once the field is energized, you canít turn off the output of the alternator. AeroElectric Connection touches on PM alternator such as the Rotax internal alternator, then it says it will discuss more in the next chapter, and the. In the next chapter doesnít really say anything.

So my question to you is removing the field what is cooking all these regulators? Another forum said that if you ran the ext. alt and the internal alt in parallel like Rotax suggests, the ext alt would take all the load (higher set voltage) and the internal alternator would continue to make power but would not be using it (until the ext alt was fully loaded and the voltage dropped to the same level the int alt was set at) and toast the regulator. I have read in a few places to keep the regulator happy, keep load on th internal alt.

I guess my question is, is it actually safe from a regulator health point of view to run these alternators in parallel with the int alt taking almost no load?