I have never got any useful prediction of output by loading a coil. It ought to work but as I have found a better way I have never bothered to struggle with it.
I use the test coil to determine cut in speed as you have done. I then accurately measure the coil resistance and from that I find the winding resistance. knowing the number of coils in series per phase and for star there are 2 phases in series.
At the speed you want to know the power you work out the open circuit voltage, subtract the battery voltage to get the internal voltdrop then divide by the resistance to find the current.
Say you have a cut in at 12v of 100 rpm and you want to know the current at 400 rpm.
At 400 rpm you generate 48v, subtract battery volts leaves you with 36. Divide this by the resistance to find the current into the battery.
This always gives an over optimistic answer and to make it work properly I have to multiply the measured resistance by 1.3 ( don't ask why but it works).
This does assume that you can accurately measure resistance and most people can't.
If you load your test coil with a resistor that halves the voltage then the coil resistance should be equal to the resistor. Unless you have the exact resistor or can measure a variable one it doesn't help.
You should be able to work it out from the drop with any suitable known resistance but most of the commercial low resistors are very nominal in their value, that and connection resistance at low levels may be why I have never got sensible results.
Learn to make accurate resistance measurements by the volt drop method , measure the coil resistance and you will be ok.
Flux
[ Parent ]
