larsb said:
the stator width is roughly proportional to the power - twice as wide, twice as powerful.
-The power is proportional to airgap diameter squared. Twice the diameter, 4x the power.
I take that to mean that there is no direct correlation between physical motor size and power. The stator width dictates the maximum amount of power I can dump into it without it overheating. How fast it'll run at that V&A level depends on the windings, so the only way to know for sure is opening the shell and counting.
Awww. I was really hoping I'd be able to avoid that since I don't want to invest in proper tooling and I'm not sure if I can put it back together again. On the other hand, I may have damaged the motor anyway the way I ran it.
It had two thermal shutdowns already. Once after riding for an hour at top speed on flat ground and the other time I attempted a long gradient I knew it couldn't possibly handle. The first time, I was surprised it ran fine afterwards after cooling down.
I don't remember the exact gradient, something around 6% probably. It ran about 2.5km before finally overheating and shutting down. That time, it took a lot longer for the motor to cool, probably around 2 hours.
It ran again afterwards but overheated really easily on any gradients.
I understand now that it's either opening the shell beforehand to count the windings or carefully monitoring temperature.
I was able to touch and keep my hand on the shell both times without burning myself. The first time it felt just unpleasantly hot, the second time I only could keep my hand on the shell for 20 seconds or so until it became too painful. I'm not sure what that would translate to in terms of winding temperature. I used it for daily transport, my usual riding distances were around 10km on flat ground. It seemed to not overheat then.
To monitor the temperature more accurately during use a sensor needs to be installed.
I guess it may be possible to cram a sensor into the motor cable slot, but the axle is so far from the windings that it wouldn't be very accurate. The values would only be meaningful if someone had the same motor and could tell me the correlation between axle and winding temperature.
For reliable commuting use, practical experimentation did work for me. I felt I would've not been able to disassemble the motor damage-free with basic tools but couldn't invest in proper tooling at the time. I don't depend on it for commuting anymore so I'll hammer it apart and post some pictures of the internal damages.
Thanks for clearing up my misconceptions. I realized now there is no way of trying to simulate for a motor with unknown characteristics based on its visual size.
That also means I do need to buy tooling for my build.
