Allex said:
I never said it was diff. But it performs diff at the same voltage/amperage, right?
That is how most people do.
What about Stealth users or Mac users? They use same battery but swap motors to get different performance. They don't touch the controller nor the battery. When a person order e-kit, he decides on a specific battery and then he thinks twice on which turn count to get for his ride.
And then we have a bunch of people who, like you said, use 24s and make their Xie Chang blow because many use their systems at their limits. This goes for batteries, motors and controllers.
So are you suggesting that everybody should buy MXUS3k 3T instead of 4t, lace it to 24 instead of 26" drop the voltage but increase the DC amps - in the end everybody will be happy because of the cooler running motor?
80% is now "most". hmmm.
Why should someone need to change anything on a $10k ebike (or whatever they cost now)?
MAC should be ashamed of themselves for calling one motor a "hi torque" motor.
I didn't say anything about dropping the voltage, except to point out how to get identical performance, efficiency, etc. from the motor people are saying will run hot or that it must run a smaller tire to survive. I also would never recommend someone run a 24" bicycle tire, or any bicycle tire with a high powered hubmotor. There's a lot more variety in the resulting OD of a wheel using a moped or moto tire.
I always suggest using the smallest wheel you can live with, because all hubmotors are happier at the resulting lower gearing. On her craptastic scooter/ebike my daughter climbed steeper hills with no heat issues than I can with my cargo bike, and that's with a same design motor with only a 25mm stator. Sure her load was lighter, but not much more than many of you, so what made it possible was the 16" OD wheel on the motor and a setup for only 25mph top speed.
Current is where most shoot themselves in the foot, and it's not so much the battery current, but the phase current, because that's the cause of most motor failures. Even the technical people at the Chinese controller factories don't get that part, because they try to apply what's done with low power unstressed hubbies which need help in startup torque to high power controllers running powerful high torque hubbies. The result is unnecessarily high phase currents that kill controllers and motors, and have such uncontrollable launches that people look for bandaids to smooth starts but leave the system wide open to heat failures in common partial speed conditions. To answer your question about current I'd say yes and no. Yes higher battery current, but no probably lower phase current limits. That would be qualified with the recommendation that everyone take the time to properly tune their system to perform it's best. It is a lot less effort than changing batteries, controllers, or motors, but is likely to produce better results....Plus it doesn't cost anything. This is an all but ignored topic on ES.
Your idea of swapping a motor and not changing the controller settings is about the worst idea I can think of.
Did you know that Justin's tests showed the stator of a 7 turn 9 strand 9C hubby starts to saturate at 70 phase amps? That would suggest that these 4 turn motors may start to saturate around 125A in phase current. My results running my 2 turn very similar motor at 250A peak on the phases without drastic heat issues would support that conclusion, as does all the heat problems people have with slow wind motors pushed to silly high phase current limits. Saturation isn't a fixed point where you're fine and suddenly hit a brick wall, but you start to have decreasing returns with increase current with lower efficiency (extra heat) as the result, so with cooling mods you may be able to dip into the beginnings of saturation, but it's best to avoid it.
Misconceptions are rampant in these regards, and not just with ESers. Motor and controller manufacturers are typically right there too. Other than to stop spreading baseless myths, the only broad recommendation you'll get out of me is a smaller wheel size. With so many using top speed as their performance gauge, the 4 turn 9rpm/volt will leave you wanting, probably even after spending extra money on a high voltage controller. With a 12+rpm/volt version it's certainly not "dangerous", but as you push the controllers higher you'll want to check them for heat, but I think that's the motor most would be happiest with. All of the motors I use are 16rpm/volt or higher, so controllers are the only thing I take care in not pushing too hard.
The other thing I caution people about is shooting for a high top speed on the road with a bike you want to ride slowly under heavy loads off-road. Regardless of the winding, if you're set up for high speed, then riding at low speed has lower efficiency. When I increase the voltage on mine by 50% I took about a 20% hit in wh/mile at similar errand running speeds. While my bike has the torque and power to blast up incredibly steep mountain roads, and can dump the massive heat, I would never consider trying to cruise up the same roads at low speed. It's the same reason Zero's dirt bike is geared lower than the street machines. Big heavy high efficiency motors get you the closest to having your cake and eating it too.