Following up, we indeed do not have data on ESC heat dissipation.
A couple of ideas for how that could be measured would be:
- measuring total power input and power output on each phase
- would require at least 5 oscilloscope probes (to measure voltage and current of/through the motor phases), and possibly an additional two to measure the power input if not using a power supply that provides those values already in a consumable / recordable form
- would also require low resistance, high power-capacity resistors to be installed for the current measurements
- measuring temperature over time in an enclosed and insulated chamber/container while running the ESC, and estimating watts used by the joules required to change the temperature of the volume of air/liquid in the chamber by the amount changed
- assumes perfect transmission of heat generated to the surrounding medium and then to the thermometer, neither of which is guaranteed
Given the voltage output of a battery also generally drops when under load, and the load for a vehicle depends on how many motors are being run at a given point in time and at what level (plus any other electronics), I expect that even a rough estimate for practical scenarios would be quite difficult to obtain.
In terms of true physical limits I suppose you can be certain that it’s more than zero watts, and less than the maximum current draw of the ESC. Some more practical limits may be determinable from the efficiency of the MOSFETs on the ESC, although that is most likely also variable with voltage, and the amount each one is switched on would depend on the motor load (but perhaps that averages out, given the phases are powered at least roughly in a sinusoidal three-phase pattern). If you’d like I can ask if we’re able to share which MOSFET is used in the Basic ESC, or at least the efficiency data in its datasheet (assuming there is some).
Beyond that, this alternative controller managed some efficiency improvements over our Basic ESC (achieving the same RPM in the same conditions / “completing the same work” with less power), so (if my logic isn’t failing me) that seems to suggest the Basic ESC is at least converting that amount of power to heat (because it’s not required for the work to be completed). Accordingly those improvement values may be usable as a more helpful lower bound, albeit a very rough one that varies with T200 RPM (and may incorporate some inefficiencies of the thruster?).