Efficiency

[maxxximatoze]

Originally Posted by nuz69

Unless a heavy drop in motor RPMs like 35000 to ~9000, but I don't think that such RPMs drop is possible, even at 3000Watts.

Very very old post but I answer just for fun. So I guess...

The magtrol that castle was certainly using for this test is limited to 10Krpm (seen elsewhere a post from Pdelcast in this forum) and the power supply was certainly their sorensen 80A (also seen elsewhere a post from Pdelcast in this forum).

So to get the last point of this graph at 1Nm and 10000rpm, it gives 1047W (10000/60x6.28) of mechanical power, which is 76A at 15.4V and 93% motor efficiency and 80W losses for the 1515 (see http://bavaria-direct.co.za/constants/ with 1515 parameters to verify, with I0 2.7A at 15.4V measured on my 1515, and rm 0.006ohm and so loaded KV at 76A was around 2145 rpm/v due to the back emf at 76A and to 0.006ohm phase)

This was certainly done through a reductor of around 3.3 ratio so the rpm can be reduced from around 33000 rpm at around 0.3Nm to 10000 rpm and 1Nm, which give the same power of aroud 1047W. And like every pinion/spur couples, the efficiency is not 100% but more like 97/98%, so 0.93x0.97 gives around 90% effciency at the dyno.

With these numbers, everything seems pretty coherent.