Rewind a cyclone 3kw motor for more power ?

By that last do you mean motors manufactured by Headline Electric Co Ltd in Taiwan

or something else?

About the only way you can really 'cheat' might be to re-wind with square magnet wire. The square cross section (assuming it is wound properly) gets you a slight increase in copper cross section. So for any given number of turns you could run slightly more amperage, or slightly increase the number of turns for the same amperage.

The last time I worked with the stuff, I believe the extra cross section effectively bumped the wire about one gauge size. eg - 12 gauge square wire was equal current carrying capacity to 11 gauge round.

But again, bleeding edge stuff. You'd likely never notice the change on the street and the square wire has to pack correctly to get the benefit. But if looking to squeeze every last watt for a second or two on a race....

https://duckduckgo.com/?t=ffab&q=square+magnet+wire

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/

Click to expand...

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 is disagreeing with what others have been saying on the topic

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 ?!

Click to expand...

Think of it this way. Why do electric cars run on hundreds of volts DC? Its just more efficient. Now think of our power grid. Several thousand volts going thru those tall, high tension lines for the same reason. Its much more efficient to move high voltage vs high amperage.

If you double the voltage and 1/2 the amps you produce less heat therefore less energy is wasted. You're still giving a few hundred watts to an ebike motor no matter how many cells are in your setup.

We have this same debate over on the Rc forums constantly and there are plenty of armchair quarterbacks who doubt those with experience. Everyone who goes to a higher voltage setup on an Rc heli or plane ends up glad they did with few exceptions.

And of course for our ebikes just like in Rc, around 50vdc (or maybe 60, tops) is where most of us draw the line for safety reasons. You probably knew that but I'm just including it for the folks following along at home. Thats 12s in lipos or 14s to 16s in LifePO4.

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.

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.

Click to expand...

Same with KTM, they use something like 80s in their Freeride

https://endless-sphere.com/forums/viewtopic.php?t=92260

I think the biggest reason is price, high amp stuff is more expensive and probably heavier in all. Also wires don't need to be as thick and heavy.

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.

Click to expand...

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:

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 ?

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.

Click to expand...

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.

Lets say you're running a 12s li-ion setup with a 200kv motor and doing 25mph uses 800 watts continuous. Going to a 6s setup would double your current and you would need a 400kv motor to get that same 25mph. Remember that more amps equals more heat regardless of voltage. So you would end up needing more than 800 watts to hit 25mph since you'd be wasting a whole lot of current in the form of heat. You'd have a hotter motor, esc, batteries and even the wires and connectors. All that heat is lost efficiency.

And you simply would not gain that efficiency back by having 1/2 the number of turns in your motor and thicker motor windings.

Its the same with electric cars. You just wont find a low voltage, high current setup. Too much wasted heat.

Yet there are plenty of motors that run on super low voltages which are some of the most efficient in the world.
Take an astro motor for example.. ultra low pole count.. sky high kV.. taps out at ~40 volts.. eats current for breakfast.. still the most efficient motor you could fit on a bike, a decade after it's introduction.

Leafmotor 4T? has a higher efficiency peak than any hubmotor in it's size. Hits 40mph on 48v. Hits the golden 90.5% efficiency peak in the real world. Will easily consume 40-80A to do this. No problem if you have a THICK power current bus. I saw 90.5% efficiency in real life. If i didn't have 10 gauge wires coming out of my controller and an extra layer of solder moving current to the FETs, i would have experienced that efficiency drop you're talking about.

The real reason high voltage is preferred in OEM setups is that as you go higher into voltage, the smaller the power bus you need. You don't have room for a copper wires the diameter of your head, so they go with hundreds of volts, not tens. But then you need to spend more $ BMS, more series connections, more wiring points from the pack to the BMS, etc.

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:

Click to expand...

Glad it took. We're still arguing about these things on this forum today and i'm surprised the misconception still remains at this point.

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 ?

Click to expand...

A motor will produce a given speed based on voltage alone first, amps second. If we have the same winding and feed it lower voltage, you can throw amps at it till you're blue in the face but all it will do is produce more torque.

Conversely, if you don't give a motor enough amps to reach it's top speed.. you will be WAY out of the sweet spot in the efficiency curve and this could create excessive heat itself.

You should play with the ebikes.ca motor simulator. It's an excellent teaching tool about motor characteristics.

Sparfuchs 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

Click to expand...

As stated above

A winding that enables a top speed "much" higher than you need

will reduce energy efficiency, and thus range

to the extent most ride speed ends up being much lower than that top speed.

Like always carrying extra weight unnecessarily, or brakes rubbing when not engaged, or always fighting a headwind.

And my understanding is, the lower voltage range gives some level of torque boost at the lowest speeds where you need it most.

Shouldn't skin effect be apparent in phase windings, given that 'BLDC' are actually more like AC when it comes to phase current?
https://things-in-motion.blogspot.com/2018/12/how-to-estimate-torque-of-bldc-pmsm.html

Anyway, anyone who has access to measuring phase winding resistance, is aware of motor torque calculation formula (from article above) and played around with ebikes.ca calculator by taking motors and slapping gear reduction on it will immediately understand that high KV motors with very low phase resistance and with a ton of gear reduction rule supreme, *period* (small wheels, that much more efficitvely convert Nm into thrust, too).

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's why very compact 'crank drives' like Tonsheng have stump-pulling torque - it has effective 40x mechanical gear reduction inside, and you can add even more reduction by installing small sprocket upfront/large in the back for like 80x effective mechanical reduction.

Of course, each step of mechanical reduction costs efficiency - but usualy arond 1-2% if well-maintained and lubricated, and it can allow you to have tons of torque from a small motor with much better efficiency than using a lot of turns.

Middrives shine here, and not just 'pedalable' crankdrives (that have a bit schizophrenic setup that first needs a ton of reduction to the cranks, and than usually end up with MULTIPLICATION to the rear wheel to work with human power), but single or dual reduction middrives, like Tom stanton's from youtube (or yours truly).



Right now my setup is kinda torque deficient due to a very small and cheap motors on rear middrive (and 170+kg of overall weight), and crank drive is having issues with helping moving me from a stop due to lack of halls (I'll need to install an encoder or switch to a sensored motor), but with more efficient motors (like flipsky 190kv, or maybe 8080 motors) and similar level of reduction I can have a system with nearly 4kw peak (at 90% efficiency!), and top speed of about 50kmh from 26v, with overall weight including reduction hardware of about 3kg and peak torque of about 120nm at the wheel (dual motors at peak amps), when in low gear, so I should be able to climb walls even given pretty extreme overall weight.

Yea, I have a lot of space those shenanigans, so I can use very efficient chain/belt reductions (99-97% per step), but so long as we are talking things 'in principle' - high KV and lots of mechanical reduction is king, both when it comes to system weight and efficiency.

It *does* result in lower no-load losses though, that's where freewheeling comes in handy.

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!

Click to expand...

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.

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!

Click to expand...

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.

Click to expand...

Good point! That's why it is 'standard' on RC-sized motor with high KV to have 0.2 lams, and there are 0.15 now avalable. I've seen like 0.05 lams on truly high-end motors, but that's not something an enthusiast will install!

There is also hysteresis torque to consider, too... but 'iron losses' are *usually* small part of total losses unless at high speed AND low power (think downhill), and your acceleration from a stop, climbing steep stuff and going offroad in sand/snow are almost entirely dependant on your torque capacity.

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.

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.

Click to expand...

Link please?

john61ct said:

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.

Click to expand...

Link please?

Click to expand...

To be frank, 99% of it is offtopic
https://electrotransport.ru/ussr/index.php?topic=58246.0

But again, it makes a lot of sense. Very powerful motors are heavy, expencive, strain your drouputs or transmission.
A combination of two motors, especially AWD, is great for having a lot of torque for brisk acceleration and climbing steep stuff: rememer, copper heat losses due to current rise quadratically, while torque output is linear. At start, electric motors have extremely poor efficiency.

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

Link to the graph! Let's have a look see.

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

Click to expand...

You would need slow down the faster motor for a more fair comparison.
A link would be easer for you but thank you, will check it out closer.

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

Click to expand...

Are those both 1:1 drive hub motors?

The MAC is not a mid-drive, it's a geared hubmotor or am I missing something.

mac motor has internal 1:5 gearing. both motors have 1:5 gearing.
But to give them about the same rpm the mac 12 motor has an extra 1:3 gear ratio and the Mac 6 motor has 1:6 gear ra
tio.
The point is the Mac 6 motor has a much better potential as a mid drive than the Mac 12 motor in both torque,speed and overheating

I see what you are doing now. Got it. I only bring the speed the same as to factor out the wind but at that speed it does not matter.