Thanks a lot for your reply TrotterBob,TrotterBob said:More turns means a lower kv rating and will decrease motor speed while increasing torque. It also means slightly more resistance in the windings which lowers the maximum wattage that the motor can handle.
I'm not an expert and dont rewind my own motors, but I've had a few done with a single strand wiring and lower kv/higher voltage and was satisfied with the results. HV setups are typically more efficent. Double the voltage and half the amps produces less heat from the motor/batteries and esc.
If you really want to do a deep dive into understanding brushless motors this is a good source of information.
https://www.rcgroups.com/electric-motor-design-and-construction-361/
Sparfuchs said:Thanks a lot for your reply TrotterBob,
and thanks for sharing that link.
But does "Double the voltage and half the amps produces less heat from the motor/batteries and esc" also mean same torque performance ? Because i got told that the same torque produces same heat. So less heat has to mean less torque ?!
TrotterBob said:I know I'm going to get some doubters on this topic. And for those who do, tell me this. Why dont you see any ebikes or small EVs running on 6s setups? Everything is at least 8s or better and thats for the eskateboards. Even the OneWheels run with packs up to 15s.
Great explained and sounds very reasonable to me.neptronix said:There's no real free lunch in switching windings. Especially when you have a motor with gear reductions inside.
Spin at a higher rpm and you get more gear friction. Go far enough into this and you'll actually lose power capability and efficiency to friction becoming a progressively larger % of the load.
Go in the opposite direction and you don't spin the motor fast enough, so it never can reach peak power or peak efficiency.
The window of an ideal balance between all motor design considerations, where you maximize peak power and continuous efficiency is extremely narrow.
The headline motors that come in the cyclones have very high stated efficiency. I believe they are optimized designs, other than the room for improvement in bearings, gears, and lubrication, which yields you a few % extra power and efficiency.
My best guess is that a faster winding will result in less efficiency here. That is purely a guess given that i don't have dyno sheets for various voltages on these headline motors.
hhmm, if i think of it i guess its because you wouldn't get enough top speed or rpm with 6s and trying to compensate that with amps would need more expansive and heavy equipment (like knurf said) but still wouldn't get you to the same speed. And it also wouldn't make sense to have enough torque to throw you off but not enough speed. I think that's also the reason why the example with the cars can't be compared to e bikes because you don't drive 200 kph or more with tons of weight here.TrotterBob said:I know I'm going to get some doubters on this topic. And for those who do, tell me this. Why dont you see any ebikes or small EVs running on 6s setups? Everything is at least 8s or better and thats for the eskateboards. Even the OneWheels run with packs up to 15s.
Sparfuchs said:Great explained and sounds very reasonable to me.
That's why i assume that cyclone has tested different windings for best results/efficiency and max. possible copper fill and decided to rewire it the exact same way cyclone did. So 12x12 with 0.5 wire. "Hopefully" they've used cheap copper wires so i can convince myself that i've enhanced the motor by rewinding it with high quality grade 2/class C (200°C) copper wires :lol:
Sparfuchs said:But now there is still one questions left to me (although it isn't about rewinding):
If i don't really need to go faster than 65kph/40mph, is there any advantage or disadvantage if i use for calculation example instead of 72v x 60a = 4320W, 52v x 83,08a = 4320W ? (Aside from advantages or disadvantages of cells than can or can't be used) Or is there even any difference in the way the motor behaves ?
As stated aboveSparfuchs said:If i don't really need to go faster than 65kph/40mph, is there any advantage or disadvantage if i use for calculation example instead of 72v x 60a = 4320W, 52v x 83,08a = 4320W
BalorNG said:Obviously, there is a practical limit to that, but:
Just it is said, by rewinding the motor to 2x speed you can *nearly* get same torque at same heat loss (amps times phase resistance)... but than you have a motor with 2x top speed allowing you to slap on 2x mechanical gear reduction, that DOUBLES your torque AT SAME copper losses!
neptronix said:BalorNG said:Obviously, there is a practical limit to that, but:
Just it is said, by rewinding the motor to 2x speed you can *nearly* get same torque at same heat loss (amps times phase resistance)... but than you have a motor with 2x top speed allowing you to slap on 2x mechanical gear reduction, that DOUBLES your torque AT SAME copper losses!
That is if you don't run into eddy current losses because you were smart enough to put paper thin laminations and also designed everything to mechanically handle the higher rpm
A motor's continuous power rating will continue to rise as the RPM rises until eddy currents start interfering. Also, the thermal capacity of the motor remains the same. So if you went from 500rpm @ 90% efficiency to 1000rpm @ 90% efficiency, you will be putting more power in and still needing to shed 10% of that at whatever multiple of wattage you're now pushing into it.
No free lunch here!
The best high rpm motors have razor thin lams and as few of poles as they can get away with to limit eddy currents. That makes the difference between an RC motor that's 96% efficient and one that's 88% efficient. And it's a totally different picture to shed 4% of 3000W versus 12% of 3000W in something half the size of the beer can. So of course the 96% efficient motor ends up with a very very high continuous wattage compared to the 88% efficient one.
Link please?BalorNG said:This is why best option is to have a freewheeling motor with high torque/low speed for this AND an other motor for high speed cruising, maybe DD/fixed gear for regen, russian thread on "2x2 drive" is quite popular.
john61ct said:Link please?BalorNG said:This is why best option is to have a freewheeling motor with high torque/low speed for this AND an other motor for high speed cruising, maybe DD/fixed gear for regen, russian thread on "2x2 drive" is quite popular.
by 1boris » Sep 25 2021 6:22pm
so is the ebikes.ca simulator wrong when it clearly show that a mac 6 motor takes much longer time to overheat than an mac 12 as a mid drive motor? Mac 6 has thicker wires
1boris said:so is the ebikes.ca simulator wrong when it clearly show that a mac 6 motor takes much longer time to overheat than an mac 12 as a mid drive motor? Mac 6 has thicker wires