When I got my nine continents 2806 hub motor, I originally got it with a 20Amp first pedal controller with 4110 FETS. This is a sensorless controller. I was running this with 36V lithium. I have a steep hill I ride up and down everyday, and I noticed that when my coast speed exceeded the no load speed of the hub, which is around 30MPH in 26 inch wheel, it would suddenly lock up the controller, and act like a plug brake, only very uneven and harsh. This is not something I wanted. The only way to clear the problem was to turn off the power to the controller, and then it would freewheel again. After some back and forth with Justin at ebikes, we came to realize this is normal. It can be solved by putting a diode in line between the controller and the battery, but then you have the voltage drop and power dissipation of the diode. IÃ¢â‚¬â„¢m a bit surprised more havenÃ¢â‚¬â„¢t complained about this.
Another thing I noticed with this controller is there was considerable cogging, which was significant at speeds over 15MPH or so when running with the throttle off, but the controller on. What became apparent is, this controller is always in regen when coasting. This is something I found annoying, and would prefer not to have, as it slows the bike down, and means you always need to have a little throttle on, even going down hills. Another problem is, the phase wires would heat up noticeably at the anderson connectors, even with currents of around 17A, and the controller would get fairly warm. Also, the no load amp draw was around 2.5A at full throttle.
After all this, I decided to try a different controller. I went with the controller sold by hightekbikes, normally used with the AOETEMA motors. This is also a sensorless controller, but it starts instantly, unlike the Crystalyte controller pedal first. ItÃ¢â‚¬â„¢s no load current is around 1A, and when the throttle is off, there is zero cogging. It also seems to run a bit smoother, but it has a higher pitched almost ringing sound. I have it modified to put out up to 28A, although on hills, it stays under 25A, but even after a 10% 1 mile long hill climb at 20A+, the controller barely gets warm, and the connectors stay cool to the touch. It is clearly a more efficient controller. I have even rode 5 miles on flat ground at average 15MPH with the throttle off, so the wheel drag is not too bad.
I really like this combination, and the price was reasonable. The only thing I still find annoying is, when the nine continents is under load up a hill, it sometimes makes a scraping noise. Letting off the throttls, the noise goes away. When I get up to speed, the noises goes away. This seems like more than resonance noises. It sounds almost like the rotor is scraping against the magnets. The problem is, itÃ¢â‚¬â„¢s not consistent. Sometimes I can be drawing 24A with little noise, and other times at around 16A, thereÃ¢â‚¬â„¢s the noise. I wonder if anyone else has experienced this. This is my second 2806 motor, and they both make the same sound.