weber wrote: .. we can surely trust the two drives to correctly measure the electrical power to/from their motors. It is the expectation of large variations in the mechanical/electrical efficiencies of the motors that I was concerned about.

Yes, Ok, so we can trust that we are getting close to 3.64 kW of electrical power from the load motor, and that close to 6.23 kW is going into the rewired motor. So we know that the elec -> mech -> elec path has a combined efficiency of about 3.64 / 6.23 = 58%. We've been assuming that this is about 72% and 82%, which multiply to 59%. I would not expect the efficiency of the load motor to exceed (wild guess) 92%, given that it's 82% efficient at full power. So the test motor's efficiency is at worst 58% / 92% = 63%, for a mechanical output of 6.23 * .63 = 3.9 kW. That's over 10x its nominal output of 0.37 kW.

Granted, 63% is pretty poor, but this thing has a potato sized rotor, and it's only 72% efficient at full load. Plus, this is a worst-case scenario.

I think we should give both motors half a percent inefficiency each, so that's 6.23 * .715 * .815 = 3.63 kW, very close to what was measured. So that means the mechanical output is actually 6.23 * 71.5% = 4.45 kW, or spot on 12.0 x (to 3 decimal places) the nominal power. But that's by design; the assumed effieciencies multiplied out so close.

Remember that 6000 RPM is more than 3x overvoltaging, because the nominal speed is 1330 rpm. So this is really 4.5x overvoltaging, for a max of "only" 12/4.5 = 2.67 overcurrenting.

Ok, so here's another wish: Let's figure out the T

max / T

nom ratio at 1330 (not 1500) rpm, and compare that with the same for either 6000 RPM, or more usefully, 1330 * 4 = 5320. After all, 6000 rpm is well past the nominal speed for this motor. (Though to find the actual nominal speed, we might need to know the nominal power first... interesting.)

Acmotor, can you actually measure the speed of the coupling with the strobe, or is it more to check for wobbles or something?

Nissan Leaf 2012 with new battery May 2019.

5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.

1.4 kW solar with 1.2 kW Latronics inverter and FIT.

160 W solar, 2.5 kWh 24 V battery for lights.

Patching PIP-4048/5048 inverter-chargers.