In which way are diagrams for BL DC motors derived (and to understand)?

I'll start with a quote from another thread because I would like to dive deep in this special point (if possible) and don't want to shift the other thread.

Since years to no avail I looked out in the web to find a detailed description of a test stand and the testing method for electric motors to establish the motor characteristics and data (and the subsequent diagrams).

In web forums the diagrams are often used to underpin a certain point of view. In a lot of this cases - as far as I understand - there is a faulty interpretation in play.

I think, the test motor is fixed in the stand, has a DC source (battery) which will supply a constant voltage (say 48 V) with no relevant drop when under load (until max. current), and between both an appropriate motor controller unit. There is a adjustable brake (mechanical, hydraulic or electric) coupled to the motor shaft, which provides the measurements of the braking torque applied (preferably witat the otor The rotational shaft speed (rpm) is also measured.

The test starts (voltage "on") with no brake torque, so the motor spins after accelerating its rotor at its highest rpm. The measured current is low, because the power output is near zero (high speed, but no torque). The power input is used mainly to overcome friction of the bearings, air gap and electrical losses in motor and controller.

Then the brake ist set to apply in several steps a growing brake torque (replacing the load in practical motor use). The voltage is monitored (measured), the correspondent current and brake torque are measured. If there are no worries about killing motor or controller, this is done until the shaft stalls (rpm = 0). At this point the torque is at its maximum, but the rotational speed is zero, so the power output is zero.

My question is: will it be done this way or am I wrong with this idea about the tests?

Edit: The appendix is a diagram of a 48 V, 3000 W, BL DC motor (Golden Motor) and the corresponding data.

Edit2: Instead of fixing the motor (as I said above) it will be probably better to mount a lever to the motor housing and allow the motor housing to turn within a small angle and measure the force at the lever arm. So lever times force eaquals to torque.

 

If my perception of the test procedure is right, it is logical to draw the diagrams with torque at the x-axis and current etc. at the y-axis. Because torque is seen as the independend variable (it is set as (propeller) load the motor has to deal with). The respective current and rpm are seen as the results, so the dependend variables.

AFAIK all (or most of the) diagrams of electric motors (not only BL DC) are presenting the torque at their x-axis.

 

I don't see anything wrong your understanding. However, I don't know how much it really matters how you display the data as long as you understand what it is telling you. Regarding testing, the following comes from "Electric Motors and Their Applications", by Tom C. Lloyd, 1969.

 

Thank you @ziper1221