Best Leafmotor winding for 72v 150 amp controller?

[diwhyguy]

Hello! Sorry to spam the forums, but my last post led me to decide on a leafmotor and there's many different windings.

I can only find motor simulator for Leaf 5T, does anyone have data to simulate other windings?

He's my dilemma. Looking at windings from similar MXUS motor, the torque advantage for slower windings seems to evaporate after ~15mph. And because I'm running so much power, I think torque below that might not matter anyways. I don't care about top speed but losing a bunch of torque starting at 10mph compared to faster winds doesn't look great. It's hard to know exactly but it appears motors with slower windings have less watts power overall above ~10mph, even at 72v.

I'm gonna run both ferromagnetic and hubsinks, because they're cheap so why not. And I'm running an FOC Sabvoton on LiPo. So I don't think I need to worry about heat or battery resistance below 3000w. If my musings are correct, at this voltage slow speed advantage of a low KV motor is significantly reduced. And even though I don't give a crap about speeds about 30mph I might be better off with a faster winding because overall power is higher and doesn't fall off near top speed.

I used MXUS for simulation but I'm pretty sure stock MXUS is pretty similar to ferrofluid+hubsinks Leafmotor as far as heat and KV ratings. Anyways, see attached picture of MXUS sim at different windings. Even though slower winding is better at a few mph the power handling of faster windings more than makes up for it.

here is my controller http://www.cnqsmotor.com/en/article_read/Sabvoton%20SVMC/SSC%20Series%20Brushless%20Sinusoidal%20Programable%20Motor%20Controller/537.html

Also, I'm running 26" tire

Am I correct that low-kv motors are bad for power/torque at this power level no matter the speed? Simulation sure looks like it. The extra torque below 10mph is just going to throw you off the bike IMO. And having shit power at 20mph, a normie human pedaling speed, doesn't seem great.

 

[john61ct]

Getting up to 10mph easily even pointing up a big grade wth a heavy load

is exactly where mega torque is needed

after that point getting from 10 to 20mph does not need nearly as much.

And if 30mph is close to your desired top speed you should set things up so 20-2x is your top **efficiency** range.

You aren't racing are you?

And your pedalling should be helping out a lot too right?

 

[diwhyguy]

I'll be honest, the original plan was to just get a cheap e-bike kit. But it's become apparent that if you DIY you can spend an extra 30% and go from 1000W to 3000W. It's $550 for a good 1000w kit vs $800 for 3000 since I already have crazy Sabvoton controller. At this point I don't see why I shouldn't.

After simulating the MXUS motors I'm not sure lower wind is worthwhile. Yeah you get 40% more torque at 0rpm and that extra torque continues until about 10mph. But at this 72V, even a fast wound motor can climb 20% grade rapidly from a standstill. The thrust is still 100lbs. And the motors wound to hit about 30mph (as fast as I will ever go) lose half their power by 20mph. Is 200nm at 0mph really good for anything except wheelies? Looking at above graph you can see even 72V wont feed 3000w to motor above 15mph on low KV winding. The faster wound motor can take peak power over twice as high

I donno, I'm just starting to question the idea that lower KV is always better for bikes with low max speed. The faster wound motors only lose torque at lowest speed where you need it least, and have 2-3X power at speeds as low as 15mph.

Here is high speed winding climbing 40% grade. If I can get this kind of toque out of fast winding what is point of getting slow winding and losing gobs of power as low as 15mph? My 150A controller can feed whatever motor wants and hopefully ferrofluid+hub fins will keep it alive. If things go south I have a temp sensor. I just don't see a big downside to higher winding at this voltage and amp rating

 

[john61ct]

I am seriously not trying to just argue here about your bigger issues.

But

> only lose torque at lowest speed where you need it least

how can that be right?

The most torque is always needed at the slowest speeds, less needed once you get going

right?

 

[Chalo]

72V x 150A is about 11kW. That's 6-1/2 times the Leaf's rated input power (48V x 35A).

With some windings, it will turn so fast that even 11kW won't be able to carry you up to that speed. With other windings, the stator will saturate and you will burn the motor without demonstrating the torque that the current level implies.

You're fishing for an answer that doesn't exist. The answer is, use a motor that's better suited to 11kW. The Leaf 1500W has a name that should help you figure that much out.

 

[ZeroEm]

You picked up on that fast. That is one of the biggest debates on this forum. You will get as many answers pro and con of each.
The clyte H3540 is a closer match to the Leaf. The MXUS 4503 is a larger motor and not sure but think you can only have 1 gear in the rear unless you widen your rear forks.

If you bought a cheaper kit you would be wanting to upgrade before long. 1500w will do what's needed but 2000-3000w does it with ease and above that it's just fun I guess.

There is more to it than just looking at the tq ramps.
You want to make sure you ride most of the time above 50% of motor speed.

You have seen the graph on my setup. I don't ride above 28mph (anymore), spend most of the time around 15mph.
My motor top speed is 33mph and 50% is 16.5 mph.

The reason for all the debate is efficiency to get the most out of the batteries. If it's not efficient then your just making heat.
Lower Kv motors look like they have less power is because they don't draw as many amps as the higher Kv motors.
You can only get so many amps into the motor before you need to up grade your wiring.

Motors make only so much torque, the Kv does not change that.
You have all you need to know it's up to you. Nothing wrong with high amps for hill climbing, just watch the temps.

by diwhyguy » Aug 31 2021 10:11pm

I'll be honest, the original plan was to just get a cheap e-bike kit. But it's become apparent that if you DIY you can spend an extra 30% and go from 1000W to 3000W. It's $550 for a good 1000w kit vs $800 for 3000 since I already have crazy Sabvoton controller. At this point I don't see why I shouldn't.

After simulating the MXUS motors I'm not sure lower wind is worthwhile. Yeah you get 40% more torque at 0rpm and that extra torque continues until about 10mph. But at this 72V, even a fast wound motor can climb 20% grade rapidly from a standstill. The thrust is still 100lbs. And the motors wound to hit about 30mph (as fast as I will ever go) lose half their power by 20mph. Is 200nm at 0mph really good for anything except wheelies? Looking at above graph you can see even 72V wont feed 3000w to motor above 15mph on low KV winding. The faster wound motor can take peak power over twice as high

I donno, I'm just starting to question the idea that lower KV is always better for bikes with low max speed. The faster wound motors only lose torque at lowest speed where you need it least, and have 2-3X power at speeds as low as 15mph.

Here is high speed winding climbing 40% grade. If I can get this kind of toque out of fast winding what is point of getting slow winding and losing gobs of power as low as 15mph? My 150A controller can feed whatever motor wants and hopefully ferrofluid+hub fins will keep it alive. If things go south I have a temp sensor. I just don't see a big downside to higher winding at this voltage and amp rating

 

[ZeroEm]

by Chalo » Aug 31 2021 11:53pm

72V x 150A is about 11kW. That's 6-1/2 times the Leaf's rated input power (48V x 35A).

With some windings, it will turn so fast that even 11kW won't be able to carry you up to that speed. With other windings, the stator will saturate and you will burn the motor without demonstrating the torque that the current level implies.

You're fishing for an answer that doesn't exist. The answer is, use a motor that's better suited to 11kW. The Leaf 1500W has a name that should help you figure that much out.

 

[markz]

MXUS has a 5kw motor and QS has 5kw+ motors, but you need extra wide drop out widths.

 

[ZeroEm]

These will fit what you want better.
E-S Stealth Electric Bike Owners
or
EScooters/EMotorcycles

 

[ben2401]

I'll be honest, the original plan was to just get a cheap e-bike kit. But it's become apparent that if you DIY you can spend an extra 30% and go from 1000W to 3000W. It's $550 for a good 1000w kit vs $800 for 3000 since I already have crazy Sabvoton controller. At this point I don't see why I shouldn't.

After simulating the MXUS motors I'm not sure lower wind is worthwhile. Yeah you get 40% more torque at 0rpm and that extra torque continues until about 10mph. But at this 72V, even a fast wound motor can climb 20% grade rapidly from a standstill. The thrust is still 100lbs. And the motors wound to hit about 30mph (as fast as I will ever go) lose half their power by 20mph. Is 200nm at 0mph really good for anything except wheelies? Looking at above graph you can see even 72V wont feed 3000w to motor above 15mph on low KV winding. The faster wound motor can take peak power over twice as high

I donno, I'm just starting to question the idea that lower KV is always better for bikes with low max speed. The faster wound motors only lose torque at lowest speed where you need it least, and have 2-3X power at speeds as low as 15mph.

Here is high speed winding climbing 40% grade. If I can get this kind of toque out of fast winding what is point of getting slow winding and losing gobs of power as low as 15mph? My 150A controller can feed whatever motor wants and hopefully ferrofluid+hub fins will keep it alive. If things go south I have a temp sensor. I just don't see a big downside to higher winding at this voltage and amp rating

To be fair the “1500W” (35mm wide stator) Leafmotor can be run at 2000W all day and 3000W for shorter periods (during acceleration) without modification. To me this is all the power needed for something that will still handle like a bicycle. With some ATF or statorade people have run them at the 5kW level without issue. Pretty sure I even recall someone putting 8kW through a leafmotor. Good thing about direct drive: the motors are oversized by necessity since there is no torque multiplication with gearing. Still might not be a bad option for you since you get the benefit of it being 12lbs unsprung weight vs over 20lbs anything larger. Correct me if I’m wrong but the next step up, the 3000W (50mm or 45mm stator I forget) MXUS (probably the best option for you with that controller while still being not a complete boat anchor) is ~20lbs. The 3000W MXUS is the most powerful motor that is available with 135mm dropout spacing (albeit with only room for a single speed rear freewheel). The leafmotor is the most powerful motor that allows for a 6 or 7 speed freewheel and still fit in a 135mm (actually ~140mm with 7-speed) dropout.

 

[neptronix]

Using the 5T leafmotor winding in the simulator will give you a much better idea of the power you're going to get.

If you equally adjust the power to create the same torque/speed across windings, you will only find a +/- 3% difference in efficiency and torque production. So the choice of winding has more to do with what speed you want to get to on your chosen battery. That is the main consideration.

Also, 120A on a leafmotor 4T = you cannot keep the front wheel on the ground. I had difficulty with unintended power wheelies on just 48v/80A.

 

[john61ct]

Surely that would depend on the controller used and/or CAv3

True FOC being a factor, supposed to enable much more precise control and smoother ramping up

 

[E-HP]

Also, 120A on a leafmotor 4T = you cannot keep the front wheel on the ground. I had difficulty with unintended power wheelies on just 48v/80A.

I was wondering about that. Is that with a 4T or 5T? Have you tried 72V? I'm on the fence on going with a 5T or 4T and assume the CA will still be able to control the throttle ramp with either motor.

Are the wheelies with the throttle directly connected? I'm pretty sure that would be bad news at 72V.

 

[Chalo]

Also, 120A on a leafmotor 4T = you cannot keep the front wheel on the ground. I had difficulty with unintended power wheelies on just 48v/80A.

I was wondering about that. Is that with a 4T or 5T? Have you tried 72V? I'm on the fence on going with a 5T or 4T and assume the CA will still be able to control the throttle ramp with either motor.

Are the wheelies with the throttle directly connected? I'm pretty sure that would be bad news at 72V.

My guess is it has more to do with the unweighted front end of his bike, and the small wheel diameter.

 

[ZeroEm]

by E-HP » Sep 04 2021 11:50am

neptronix wrote: ↑Sep 04 2021 9:49am
Also, 120A on a leafmotor 4T = you cannot keep the front wheel on the ground. I had difficulty with unintended power wheelies on just 48v/80A.
I was wondering about that. Is that with a 4T or 5T? Have you tried 72V? I'm on the fence on going with a 5T or 4T and assume the CA will still be able to control the throttle ramp with either motor.

Are the wheelies with the throttle directly connected? I'm pretty sure that would be bad news at 72V.

Don't have a phaserunner. Adjusted the ramp up rate in the CA3. I run 72V and did not like the jerk and only had to delay full throttle a second. I have a trike so no wheelie issues.

 

[Bullfrog]

First you need to define whether the 150A is battery amperage or phase amperage. If it is phase amperage, you are fine. Assuming you plan on running 72v and 150A phase current or even more for that matter:

A. You can push a LOT of amperage for a short period of time. The shorter the time the higher the amperage you can use without doing any harm to your motor.

B. I'd use the Grin Tech Motor Simulator and select the RH212 motor to get a good idea on your steady state temperatures. Steady state, you should stay below about 130C...because as you go over ~130C, the temperature will start to rise quickly and you don't have enough cushion to climb anything without exceeding 150C....150C is the absolute maximum for most motors without doing an permanent damage steady state.

C. To achieve the speed you want, select a smaller diameter wheel and a higher Kv. Kv and the motor winding i.e. 4T, 5T, etc. are inversely proportional (the lower the winding number the higher the Kv). The diameter of the wheel determines the effective gearing...a smaller wheel is easier to turn than a larger diameter wheel so the smaller wheel is less likely to over heat. I would NOT go with a 20" wheel because you will have "Radial" lacing with zero spokes crossing each other...it works but is much weaker than a spoke lacing pattern where the spokes cross each other i.e. one cross, 2 cross, etc. IMO a 24" rim is the sweet spot.

D. Going with a 72v battery is smart IMO, you get more power (Watts) with less heat since the heating is proportional to the amperage squared.