whalesmash
🧲 New user
Hi everyone, this is my first post here and I apologize in advance for bringing a topic that is not quite a fit for the main focus group of this forum, but considering the parts I am looking at using, there is a much bigger knowledge base here than in any other group I have poked around in. I appreciate your feedback/thoughts.
Goal: High torque electric unicycle for use on technical off road trails (usually black diamond mountain bike trails). Preferably with a 17inch rim (22/23 inch OD tire, 80/90-17). Speed not really a goal, 40mph would be nice for the brief period of on-road travel between trails, but I prioritize torque in that 0-30mph range over top speed.
Background:
This is a picture of the current wheel that I have built. It is cobbled together using different parts from different existing electric unicycles. The main points are: 32s4p battery (Samsung 50s), Controller claims 280A peak current (no way this is battery so i make the assumption that it is phase amps). I don't think I have actually seen this number in riding. Motor uses 40mm wide magnets, 28 pole pairs. I do not know the number of turns. They claim it to be a 5kw motor, but they have used this motor across many different EUCs and each one claims a different power rating despite being the same motor. The motor weight is 38-40lbs with a tire and tube. Real world wise, I have gone between 50-55 mph on this with a full battery and gotten 80% max power alarms, if that is any use in estimating what the motor is wound for. There's enough power to climb up a stair case assuming you don't loose traction, but it is much slower than what I have seen some ebikes do, if that means anything. Information is closed source and I don't have too much to go off of.
My main issue with this current build isn't necessarily that it lacks torque, but it is lazy. It does not accelerate well unless you lean super hard (IE pin the throttle to max in ebike terms). If I were to put it in vesc terms, it's like the ramp rate is slow. For an EUC, especially a trail wheel, this is problematic because leaning super far puts you in a position where you cannot readily react to the terrain. Braking also suffers since you're leaning so far off the back, trying to get the damn thing to stop.
Proposed Build:
I am looking at doing a more current heavy build with a focus on low end torque and higher phase amp delivery. A vesc controller would also allow me the flexibility to tune the ride feel for specifically what I want. Here is roughly what I have put together:
Motor: QS205(Is this enough? It seems small and low pole count compared to what I'm used to seeing) or QS275 (heavy, yikes, probably can't use the full power anyways). 5T or 6T variant of these motors unless convinced otherwise.
Battery: 24s5p using either Molicel p42a, p50b, or ampace jp40 or eve40pl
BMS: ANT or Ennoid Xlite master/slaves
Controller: Probably a 3shul cl700 or cl1000.
Questions and Comments:
Is a 5T or 6T QS205 enough torque for what I am looking for?
The pole count on the 205 is almost half of what I'm used to seeing in an EUC motor, and the diameter seems significantly smaller. I'd rather not go with the 273 due to weight, but the pole count is pretty much the same as most EUC motors, and the videos I've seen of this motor in some ebikes/emotos are impressive to say the least. I am sure the 273 would have ample torque for what I want, but I doubt i would get close to taking advantage of its capabilities.
Is my battery configuration enough to supply the phase current I want?
Note that these phase current numbers are definitely more peak values and are not sustained. I am fully aware of the temperature limits for cells/controller/motor I would quickly hit if I draw the cells at too high a current. I have been going off of the assumption that I can get 40A continuous out of whatever cells I pick for the pack, and using that number to gauge how much phase amps I can ask the controller to pull. Or... am I about to explode?
Will a spoked rim even survive this?
I'm sure I could just go with beefier gauge spokes, but my projected weight for the entire build is ~100lbs, and that is all on a single tire. I'm only 150lbs but everything adds up. I hope I don't bend axles...
Ancillary info:
Here's the kinds of trails I usually ride:
Youtube
If you made it this far, I appreciate it. Any thoughts, including calling me an idiot with unrealistic expectations are welcome
Goal: High torque electric unicycle for use on technical off road trails (usually black diamond mountain bike trails). Preferably with a 17inch rim (22/23 inch OD tire, 80/90-17). Speed not really a goal, 40mph would be nice for the brief period of on-road travel between trails, but I prioritize torque in that 0-30mph range over top speed.
Background:
This is a picture of the current wheel that I have built. It is cobbled together using different parts from different existing electric unicycles. The main points are: 32s4p battery (Samsung 50s), Controller claims 280A peak current (no way this is battery so i make the assumption that it is phase amps). I don't think I have actually seen this number in riding. Motor uses 40mm wide magnets, 28 pole pairs. I do not know the number of turns. They claim it to be a 5kw motor, but they have used this motor across many different EUCs and each one claims a different power rating despite being the same motor. The motor weight is 38-40lbs with a tire and tube. Real world wise, I have gone between 50-55 mph on this with a full battery and gotten 80% max power alarms, if that is any use in estimating what the motor is wound for. There's enough power to climb up a stair case assuming you don't loose traction, but it is much slower than what I have seen some ebikes do, if that means anything. Information is closed source and I don't have too much to go off of.
My main issue with this current build isn't necessarily that it lacks torque, but it is lazy. It does not accelerate well unless you lean super hard (IE pin the throttle to max in ebike terms). If I were to put it in vesc terms, it's like the ramp rate is slow. For an EUC, especially a trail wheel, this is problematic because leaning super far puts you in a position where you cannot readily react to the terrain. Braking also suffers since you're leaning so far off the back, trying to get the damn thing to stop.
Proposed Build:
I am looking at doing a more current heavy build with a focus on low end torque and higher phase amp delivery. A vesc controller would also allow me the flexibility to tune the ride feel for specifically what I want. Here is roughly what I have put together:
Motor: QS205(Is this enough? It seems small and low pole count compared to what I'm used to seeing) or QS275 (heavy, yikes, probably can't use the full power anyways). 5T or 6T variant of these motors unless convinced otherwise.
Battery: 24s5p using either Molicel p42a, p50b, or ampace jp40 or eve40pl
BMS: ANT or Ennoid Xlite master/slaves
Controller: Probably a 3shul cl700 or cl1000.
Questions and Comments:
Is a 5T or 6T QS205 enough torque for what I am looking for?
The pole count on the 205 is almost half of what I'm used to seeing in an EUC motor, and the diameter seems significantly smaller. I'd rather not go with the 273 due to weight, but the pole count is pretty much the same as most EUC motors, and the videos I've seen of this motor in some ebikes/emotos are impressive to say the least. I am sure the 273 would have ample torque for what I want, but I doubt i would get close to taking advantage of its capabilities.
Is my battery configuration enough to supply the phase current I want?
Note that these phase current numbers are definitely more peak values and are not sustained. I am fully aware of the temperature limits for cells/controller/motor I would quickly hit if I draw the cells at too high a current. I have been going off of the assumption that I can get 40A continuous out of whatever cells I pick for the pack, and using that number to gauge how much phase amps I can ask the controller to pull. Or... am I about to explode?
Will a spoked rim even survive this?
I'm sure I could just go with beefier gauge spokes, but my projected weight for the entire build is ~100lbs, and that is all on a single tire. I'm only 150lbs but everything adds up. I hope I don't bend axles...
Ancillary info:
Here's the kinds of trails I usually ride:
Youtube
If you made it this far, I appreciate it. Any thoughts, including calling me an idiot with unrealistic expectations are welcome
