OK, so I took a new Nine Continent motor off the shelf and went ahead with replacing the phase leads with 12 AWG wire. How liveforphysics managed to pull 10 gauge and the 5 hall leads through that channel I will never know! Unfortunately it was only after doing all this that I realized I had accidentally grabbed a 6 turn rather than a 7 turn hub from the shelf. Whoops! So even with the full 100 amps I was only just at the knee of the saturation point.
So far it looks pretty good. Again the data for the 90 and 100 amp tests have a fair bit more uncertainty than the other values, because of the tight time frame required to get the peak force readings. In this case the phase windings were heating up and raising in resistance fast enough that the power supplies would quickly get voltage limited, so I first put a bunch of parallel LiFePO4 cells in series with the power supplies to up the voltage a bit, and then even went to a large 12V SLA in order to have a high enough voltage for the 100A test.
Then I discovered that we still had around our first sample Nine Continent stator from a couple years ago, and this was a 7x9 winding, hoorah. Did the 12 gauge phase wiring fix. In this case, the phase resistance is over twice as high as the 10x6 winding in the previous test. So to get up to the current levels I had add in series to both my power supplies, plus a 12V SLA, PLUS a pair of parallel connected 24V NiMH packs.
So the peak output voltage was 12 + 24 + 10 + 8 = 54V, and even then I wasn't able to get a stable 90 or 100A current in order to really push things into saturation. The winding resistance would shoot up too fast making it hard with all these supplies to keep a steady and exact current, and then I'd have to wait an hour or so for the motor to cool down completely to try it again. But I was able to get a stable reading at 80 amps, (equivalent to 120 amps on the 10x6 winding tested above), and the results look like this:
It looks like saturation or 2nd order effects start to happen at around 70 Newton-Meters, exactly the same torque where the BMC hub started to show this behaviour. In the case of the 9C hub, the motor constant K decreases by about 40% after this point, while the BMC motor it decreased just a little more, by 46%.
So there you have it folks! One thing that became clear to me in these tests though, was that even if there wasn't any saturation/demagnetization effects going on, just the I^2R consequence of pushing the motors this far means we are in a domain that is totally outside of any useful operating zone. The windings get hot, FAST, and that has huge effect on the motor performance. I had the current going through for just 10-15 seconds in order to get a peak torque reading, then would have to put the motor outside in the subZero weather and wait a good amount of time for it to cool off.
If I was to do this test again, I would drill big hole in the side cover and spray water on the windings to keep things cool and save a bunch of time. If anyone was planning to use the hubs in a vehicle that was going to sustain these kinds of loads, then they would also want to look at active cooling.
Justin
So far it looks pretty good. Again the data for the 90 and 100 amp tests have a fair bit more uncertainty than the other values, because of the tight time frame required to get the peak force readings. In this case the phase windings were heating up and raising in resistance fast enough that the power supplies would quickly get voltage limited, so I first put a bunch of parallel LiFePO4 cells in series with the power supplies to up the voltage a bit, and then even went to a large 12V SLA in order to have a high enough voltage for the 100A test.
Then I discovered that we still had around our first sample Nine Continent stator from a couple years ago, and this was a 7x9 winding, hoorah. Did the 12 gauge phase wiring fix. In this case, the phase resistance is over twice as high as the 10x6 winding in the previous test. So to get up to the current levels I had add in series to both my power supplies, plus a 12V SLA, PLUS a pair of parallel connected 24V NiMH packs.
So the peak output voltage was 12 + 24 + 10 + 8 = 54V, and even then I wasn't able to get a stable 90 or 100A current in order to really push things into saturation. The winding resistance would shoot up too fast making it hard with all these supplies to keep a steady and exact current, and then I'd have to wait an hour or so for the motor to cool down completely to try it again. But I was able to get a stable reading at 80 amps, (equivalent to 120 amps on the 10x6 winding tested above), and the results look like this:
It looks like saturation or 2nd order effects start to happen at around 70 Newton-Meters, exactly the same torque where the BMC hub started to show this behaviour. In the case of the 9C hub, the motor constant K decreases by about 40% after this point, while the BMC motor it decreased just a little more, by 46%.
So there you have it folks! One thing that became clear to me in these tests though, was that even if there wasn't any saturation/demagnetization effects going on, just the I^2R consequence of pushing the motors this far means we are in a domain that is totally outside of any useful operating zone. The windings get hot, FAST, and that has huge effect on the motor performance. I had the current going through for just 10-15 seconds in order to get a peak torque reading, then would have to put the motor outside in the subZero weather and wait a good amount of time for it to cool off.
If I was to do this test again, I would drill big hole in the side cover and spray water on the windings to keep things cool and save a bunch of time. If anyone was planning to use the hubs in a vehicle that was going to sustain these kinds of loads, then they would also want to look at active cooling.
Justin
some are pretty cool ones too.. lets say doing 68km/h on a snowy road, and getting pulled by the cops, and then running away from them.. yup! 
and as a proof some I have on video 
