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Thanks for the replies.
Parasitic load:
I think this is in the noise.
When there is no load on these generators they basically present very little resistance, so with no electrical load almost no parasitic load. You can easily spin the generator by hand and it will coast for a couple of rotations. There is minimal "cogging" where the rotor feels like it gets stuck in ruts made by the permanent magnets.
As an aside, the orange generators to have substantial cogging, like will lurch forward forcibly in your hand, but I suspect that overall they have very little parasitic load as well when you average the torque for a full rotation. The magnetic field has to be pushed through but then also gives a push, and averages out to ~0. The orange generator is like pushing a car up and down hills, the monkworkz generator is like pushing a car on a flat road, both averaging out to around the same energy for distances that include many climbs and descents and have zero net elevation gain.)
However if you short the leads together it feels like you're churning ice cream, still very smooth, and the faster you try to spin it the more resistance it presents. But with no load there is very little mechanical resistance.
I have measured the mechanical to electrical efficiency and it's 90-95% in some case better than that, then the electrical efficiency of the regulator is substantially better still.
Alternators require the magnetic field to be actively generated and in rough numbers that's probably about a 10% efficiency hit, i.e. you need to put in around 1 amp of field to get 10 amps of current out. That will be less at higher RPM. Not something I have measured but that is generically how that works.
I would expect the Monkworkz device to be superior in mechanical to electrical efficiency at all RPM because it doesn't have to generate the magnetic field.
Anyway, parasitic loss is close to zero. If there is no load there is very little drag torque presented to the drive.
When it is actually making power there is loss in the conversion from mechanical to electrical power. Here is a quick worst case estimate of what the loss would be:
amps * volts = power
30 amps * 14.4 V = 432 watts <- call this power made good, why you bought the device
Power out /(regulator efficiency*Generator efficiency) = mechanical power required
432/(0.95*0.9) = 505 watts <- overall mechanical power harvested from your engine
lost power = 505-432 = 73 watts or ~0.1 HP. <- power you want to minimize
73 watts is high because the regulator efficiency is actually quite a bit better than 95%.
So even worst case scenario, the parasitic load is 0.1 HP, or less than 0.1% of the power output of most lycomings. Even if the alternator was a lot worse the parasitic load would still be in the noise(to me anyway).
But yes, whatever power is lost does need to be taken away with cooling and that is why there are blast tubes. The blast tubes are constrained to put the air directly where it is needed and nowhere else. I've measured the impact on cowling pressure differential with and without and it's less than the difference of 1 knot of airspeed.
Comparisons to other alternators:
I'm not an expert on other products, one tester, Dave Anders(with a very fast RV-4), claims that with a vac pad alternator he was not able to taxi and get a positive charge, he needed around 1400 (crank) RPM to show a positive charge, with the Monkworkz generator he gets away with ~1000 RPM. 1400 RPM is too much to taxi with and overspeeds his taxi or overheats his brakes.
Moisture protection:
The circuit board has a conformal coating baked on for moisture protection and lives in a machined 6061 box, the generator has sealant around the wire transitions. The construction isn't any different from other motors on your plane like in the starter or the alternator for that matter.
Thanks,
Bill