Using RC motors on E-bikes [Archive]

[MitchJi]

Hi David,

Great news!

I'm totally stoked to hear this.

Me too!

Outrunners (most outrunners) have an overhanging bell (no support bearing at the bell skirt). This overhang allows the can to migrate a tiny bit when encountering sharp bumps. This shaft flex/bell migration causes back EMF confusion in the ESC, sometimes. Now, a high quality ESC, like the HV110, is far less prone to losing sync with the motor. Whereas cheaper ESCs cannot cope as well. Also, my costly Plettenberg has a skirt bearing to eliminate can flex.

I think sealed bearings with a bearing to support the bell would be excellent both to reduce back EMF confusion and for overall structural integrity.

I personally want to design the motor with an integrated blower to keep things cool on really steep hills at lower speeds. The biggest problems occur when the motor is at very high currents and barely spinning (hills, grass, etc).

Integrated blower is excellent if its quiet.

I'm also targeting insane power levels and fairly high motor rpm since that is what I'm passionate about. The motor will be in the 3lb range with continuous power levels of 4-6Kw with peaks of over 12Kw.

I think a Kv of 150 to a max of about 200 would be best. I think this is crucial.

I think a max diameter of about 2.5" and a max length of about 3" is about right.

I think 4-6Kw is way more than necessary. I would rather have a very high quality 2-3Kw, smaller and lighter motor. A $400 price is fine if it is an excellent motor but I would rather pay less for a less powerful motor if I had a choice. Maybe two or three different models of a very similar design.

What's the Castle SHV250, is it a upcoming product?

specifications here:
http://www.castlespecialprojects.com/csp_90_volts.html

90v - Max Input Volts
122 AMPS - Case 1 - No Cooling air / cooling air 0-200LFM in
$599.00 - Price >10 units Controller configured with Industrial Software

Available Q4 2008

Thats 11kW

A motor that works with a little less expensive esc would be nice.

hall sensors or no, etc.

Hall sensors would be awesome!

Do you have any idea when this might be available?


I think your best bet for getting great feedback would be to make a preliminary model available for free to everyone subscribed to this thread for beta testing. I'm pretty sure most of us would be willing to help out at no charge


Once again, great news!

Thanks!

Mitch

 

[johnrobholmes]

Good to see you here CNC addict. I can give some input on motors for sure.

2kw is enough for most people. Easy enough to make a short stack motor.

I want a 4kw motor, that would be awesome.

A blower would be good, but it can't be too loud. Electric riders love stealth.

I would recommend a slotless design for a freespinning motor, if you can get the KV low enough without using a stator. It would make a system need no freewheel.

A pancake style motor would be easier to mount inside the triangle or between the cranks.

10mm or 1/2" shaft would be good.

Give the motor a stout frame with mounting points along the can on front and back.

Make it all black.

 

[CNCAddict]

If it can be matched with a gearbox of similar weight. If the motor + gearbox is in the 3-4kg range, with a total weight (including chain to the rear wheel, rear sprocket, mount brackets) of 5-6 kg then the total system will blow the current high power ebike solution (Crystalyte X5 hubmotor) out of the water completely.

Hmmm, does anyone know of high quality, long lasting gearbox's that don't cost a fortune? I can design my own...but that would be a LONG time before I had anything functional or affordable. I love the idea of using a dual stage belt reduction since they are immune to just about any type of contamination and the belts/pulleys seem to last quite a while. I think Recumpence has some plans to offer a kit, so I wouldn't want to encroach on that area.

I think sealed bearings with a bearing to support the bell would be excellent both to reduce back EMF confusion and for overall structural integrity.

Hmm, if the motor is similar to the 40 series motors I'm making now it won't have a support at the end of the bell. The problem with the cheap motors is that most of them use an undersized shaft which is not stiff enough to support the spinning bell. A tiny bit of flex at the shaft can cause wild resonance which quickly ruins motors (just ask my HXT motor). The problem with large diameter ring bearings is that they are expensive, and they don't like high rpms. These large diameter bearings also have high surface speeds at the seal interface which causes more problems. I'll test the motor out a lot to make sure there are no problems in this area.

Integrated blower is excellent if its quiet.

That could be a problem, anyone want to design a fan speed control which follows motor current/temp?? Maybe an Arduino could do that pretty easily??

I think a Kv of 150 to a max of about 200 would be best. I think this is crucial.

I'll offer several Kv's. A 3 turn 6045 motor would have a Kv of around 130. The 2 turn would be around 200. So I think that will be good. Of course the 2 turn would scream at 85V which is where I want to run it

I think a max diameter of about 2.5" and a max length of about 3" is about right.

Hmmm, I'm shooting for a 75mm OD (~3”) or I'll start getting too close to my 40 series motors. There will be several lengths available.

I think 4-6Kw is way more than necessary. I would rather have a very high quality 2-3Kw, smaller and lighter motor.

My 40 series motors will do 2Kw, but at a higher rpm than you may want.

A motor that works with a little less expensive esc would be nice.

It will work fine on any sensorless controller. I'm also waiting for a good high voltage affordable controller but that is still a big question mark.

Hall sensors would be awesome!

I'll investigate how much work it will be to design that in. Anyone have links to a well designed hall system? It seems like most manufacturers glue them to the windings..yuck.

Do you have any idea when this might be available?

Depends how well my 40 series sell. If I have some cash on hand I can get things done A LOT faster. Right now I'm on a shoestring budget, but I hope that changes soon. In all seriousness it looks like I could have a prototype going sometime around christmas.

I think your best bet for getting great feedback would be to make a preliminary model available for free.......

LOL, well somebody will get a free one to help me test. I suppose it will be who has the most experience However, you'll have to supply a controller and battery pack that can dump some serious juice.

I would recommend a slotless design for a freespinning motor, if you can get the KV low enough without using a stator. It would make a system need no freewheel.

That is a good idea except the prototyping time would be a huge unknown. I would love to build a slotless motor with rotating backiron for a very low Io and zero cogging. My motors are presently full pitch motors with HUGE cogging torque. So at low speeds this will excite some resonance in various parts of your bike. However, taking steps to reduce this torque often has a negative impact on motor performance. I'll mull this over.

A pancake style motor would be easier to mount inside the triangle or between the cranks.

Pancake motors are not something I can do right now. Only the standard radial flux motors at the moment, sorry.

10mm or 1/2" shaft would be good.

Hmm, I'll probably do a large internal shaft and then have it step down to whatever size you guys want. I was thinking 12mm internal....so that would make anything less than that possible for the output shaft.

Give the motor a stout frame with mounting points along the can on front and back.

Hmm, the front will have 4 4mm or 5mm threaded holes, and I'm thinking helicoils would be good to provide some extra durability. The rear mounts depend on the configuration of motor. I'm currently aiming toward the external rotor design (like my 40 series) since this style is very cost effective, light, and powerful. However, if I do go slotless...it may be possible.

Make it all black.

Is the color really that important!?

 

[MitchJi]

Hi David,

Hmmm, does anyone know of high quality, long lasting gearbox's that don't cost a fortune? I can design my own...but that would be a LONG time before I had anything functional or affordable. I love the idea of using a dual stage belt reduction since they are immune to just about any type of contamination and the belts/pulleys seem to last quite a while. I think Recumpence has some plans to offer a kit, so I wouldn't want to encroach on that area.

A motor or series of motors that work well with Matt's (Recumpence) belt drive unit would be excellent. I think he is open to making slightly different versions of the drive so maybe you can work together to come up with an integrated solution.

I think a max diameter of about 2.5" and a max length of about 3" is about right.

Hmmm, I'm shooting for a 75mm OD (~3”) or I'll start getting too close to my 40 series motors. There will be several lengths available.

I came up with a 2.5" diameter as an approximation of what would fit the drive Matt currently plans (2" x 3' tubing). The motor diameter needs to fit inside the 3" dimension. I think he could use 4" x 2" tubing and easily accommodate up to about 3.5". For length if its longer than roughly 3.5" to 4.5" it will be difficult to fit between the pedals. I think working with Matt on sizing and mounting will be your best bet.

LOL, well somebody will get a free one to help me test. I suppose it will be who has the most experience However, you'll have to supply a controller and battery pack that can dump some serious juice.

I think Matt would love to use one of your motors, with his drive unit on his next build, so if he is ready when your motor is ready for testing he might be a good choice.

My 40 series motors will do 2Kw, but at a higher rpm than you may want.

2.5kW sustained with 200kv or under for a motor usable with Matt's drive would be excellent. 4kW (if its affordable) wouldn't hurt

Thanks!

Mitch

 

[voicecoils]

It my be necessary to have at least two designs, a lower powered cheaper one under 4kW cont. (with corresponding less expensive less strong mechanical supporting components) and a higher powered balls to the wall version that would be suitable for the SHV110 and SHV200 controllers.

Being able to run an RC designed motor at 72v nominal packs will be a great step forward. Higher voltage means thinner cables too, which is a bonus in weight and routing on a bike.

With shaft support, is it advantageous to have the shaft supported in the motor housing and at the end of the shaft (with the gear,sprocket,pinion, pully sitting between both supports)? This is something which could potentially be integrated in an ebike gearbox design if mechanically desirable. Perhaps it would aid in the motors' mechanical design. I could be talking nonsense, just throwing out some thoughts.

I'm not personally interested in more then a two stage setup, and I think minimising mechanical complexity between the motor and the rear wheel is worth aiming for for reliability and minimising maintenance and adjustments.

 

[recumpence]

Hey David!

Really glad to see you here! I am also thrilled to see you pursuing the 60 series we talked about. Very cool!

A couple things;

#1 Yes, $400 is about perfect.
#2 200 KV is ideal for our purposes.
#3 I think a very stout shaft in the 8mm to 10mm would be a very good starting point.
#4 I can make the reduction system for your motor specifically. I have my E-box design that is good up to 2.5 inch diameter motors. But, I also have a modular design I am working on that will take larger motors and be reconfigurable to a dual stage setup with adjustable layout (hard to explain without pics).

Anyway, if you want to talk directly, you have my number. I would be more than happy to work with you on an ideal drive system for the 60 series.

I also want one of your 40 series motors with an 8mm shaft.

Matt

 

[johnrobholmes]

If you skew the stator a bit it will cut down on harmonic vibration of the motor, and smooth out the startups as well. It would be a good alternative to a slotless design.

 

[MitchJi]

I think sealed bearings with a bearing to support the bell would be excellent both to reduce back EMF confusion and for overall structural integrity.

Hmm, if the motor is similar to the 40 series motors I'm making now it won't have a support at the end of the bell. The problem with the cheap motors is that most of them use an undersized shaft which is not stiff enough to support the spinning bell. A tiny bit of flex at the shaft can cause wild resonance which quickly ruins motors (just ask my HXT motor). The problem with large diameter ring bearings is that they are expensive, and they don't like high rpms. These large diameter bearings also have high surface speeds at the seal interface which causes more problems. I'll test the motor out a lot to make sure there are no problems in this area.

Integrated blower is excellent if its quiet.

That could be a problem, anyone want to design a fan speed control which follows motor current/temp?? Maybe an Arduino could do that pretty easily??

I would recommend a slotless design for a freespinning motor, if you can get the KV low enough without using a stator. It would make a system need no freewheel.

Make it all black.

Is the color really that important!?

Hi David,

Its a safe bet your motors are going to end up on fast bikes. At least 25mph or 30mph. At those speeds hitting a pot hole or riding in the dirt requires a well supported bell. If the Plettenburg can implement this (Matt's Terminator) maybe you can too?

IMO I think the blower is OK but I think quiet is crucial. Maybe a model with less aggressive blower or no blower with reduced sustained wattage. I would definitely prefer 2500 watts sustained quiet motor over a 4k or 5k watts sustained noisy motor.

I'm not a motor expert so there might be some other advantage of a slotless design that I'm not aware off but I don't see that not requiring a freewheel as important. If it is used with a two stage drive I would want a freewheel or oneway on the final output shaft regardless.

Color might not be important but for Australia and Europe its important to have a big 200 Watt label :lol:. Of course the North American version should have a 750 Watt label.

 

[recumpence]

One thing to remember about motor noise;

Much of the noise made by RC outrunners is related to the PWM sent to the motor from the controller. Outrunners require a relatively low PWM frequency to operate. I have tried various frequencies on my Plettenberg (the HV85 and HV110 controllers have this function). The only frequency I have found that works well on outrunners is the low 8khz setting. This is, however, in the audible range. So, no matter how hard you try to make the motor silent, there will always be some sound.

My Plettenberg and the AXI I used to use make some sound, but not enough to matter. They make just a light muffled whine, very turbo-charger like.

Matt

 

[johnrobholmes]

FYI Castle just added a new firmware update that doesn't come up in the Castle Link software. Hit up the webpage and download it, it is supposed to aid in outrunner startup.

 

[recumpence]

Very cool!

I will have to bring my bike inside, wire it up to the USB and load it up! I wonder if the PWM is more adjustable?

John, I have a very cool drive system figured out. It is a modular setup with adjustable mounts. Should be a pain in the neck to machine (lots of parts and somewhat complicated). But, it should be awesome! I will be making one for testing on my mountain bike.

Matt

 

[CNCAddict]

It my be necessary to have at least two designs...

Yeah, there will be a range of motors so that's no problem. I'll do 2-3 stack lengths in each motor I design.

With shaft support, is it advantageous to have the shaft supported in the motor housing and at the end of the shaft...

The shaft/bearings will be huge, so no need for an end support.

I'm not personally interested in more then a two stage setup

Yeah, I love the idea of the huge rear pulley, but that method won't work with a hub freewheel and it's also a bit clumsy in appearance. A 2 stage design would still be very reliable, but would have worse efficiency in the drive system...it's all a trade off.....

I also have a modular design I am working on that will take larger motors and be reconfigurable to a dual stage setup with adjustable layout (hard to explain without pics).

We need pictures

I also want one of your 40 series motors with an 8mm shaft.

They should be finished very soon. We have ordered some 8mm shafts along with the 5 and 6mm.

If you skew the stator a bit it will cut down on harmonic vibration of the motor, and smooth out the startups as well. It would be a good alternative to a slotless design.

Yeah, that's a great idea. I'm just not sure how that effects the motor constants...need to do some research.

Hi David,

Its a safe bet your motors are going to end up on fast bikes. At least 25mph or 30mph. At those speeds hitting a pot hole or riding in the dirt requires a well supported bell. If the Plettenburg can implement this (Matt's Terminator) maybe you can too?

Sure I can add bell support bearing, but the additional hassle/wear/maintenance/cost/noise of a giant ring bearing may be better spent by just using a thicker bell. If anyone has documents on the stability of spinning tubes...that would be a huge help. It could be as simple as adding some sort of damper system to keep oscillations down?? Our airgap will be large enough in this motor to keep the magnets from colliding with the stator, but if there are any severe vibrations I'll have to go back to the drawing board.

IMO I think the blower is OK but I think quiet is crucial. Maybe a model with less aggressive blower or no blower with reduced sustained wattage. I would definitely prefer 2500 watts sustained quiet motor over a 4k or 5k watts sustained noisy motor.

If I go with a standard outrunner I may dump the blower idea. If I do a slotless motor it would be eaiser to integrate the blower.

I'm not a motor expert so there might be some other advantage of a slotless design that I'm not aware off but I don't see that not requiring a freewheel as important. If it is used with a two stage drive I would want a freewheel or oneway on the final output shaft regardless.

The slotless motors have some interesting characteristics.... Almost infinite peak torque, lower continuous torque, very high cruise efficiency(low powered), and no cogging(spin like a jet engine).

Color might not be important but for Australia and Europe its important to have a big 200 Watt label . Of course the North American version should have a 750 Watt label.

Anyone have info about how much trouble I could get in by selling 6000W motors for use on electric bikes? Maybe if I only actively advertise for use large RC planes, etc...then the law won't be showing up at my front door

 

[recumpence]

David,

I went through liability issues producing RC helis too. Basically, you should market any motor you make for RC purposes. Then it is not your fault that "Eccentric people" insist on using them for human propulsion on bikes. :wink: Plettenberg freaks out when people tell them they are using motors on bikes. If you talk to them on the phone and tell them that is what you are doing, they will hang up on you! So, yes, make sure the box says "For RC airplane use".

My new modular drive system is not built yet. I will start a thread on it when I get a prototype made.

I would love to go over a few things with you. Can I get your number?

Any thoughts on when you may be able to have a few 60 series motors (I know it is not a quick thing)?

Matt

 

[MitchJi]

Hi,

One thing to remember about motor noise;

Much of the noise made by RC outrunners is related to the PWM sent to the motor from the controller. Outrunners require a relatively low PWM frequency to operate. I have tried various frequencies on my Plettenberg (the HV85 and HV110 controllers have this function). The only frequency I have found that works well on outrunners is the low 8khz setting. This is, however, in the audible range. So, no matter how hard you try to make the motor silent, there will always be some sound.

My Plettenberg and the AXI I used to use make some sound, but not enough to matter. They make just a light muffled whine, very turbo-charger like.

Matt

So if David can design an outrunner that runs well with a PMW frequency outside the audible range it would be virtually silent. It might be an impossible or impractical request but since he is soliciting requests and ideas a silent outrunner would be great.

David,


Any thoughts on when you may be able to have a few 60 series motors (I know it is not a quick thing)?

Matt

Depends how well my 40 series sell. If I have some cash on hand I can get things done A LOT faster. Right now I'm on a shoestring budget, but I hope that changes soon. In all seriousness it looks like I could have a prototype going sometime around christmas.

If I go with a standard outrunner I may dump the blower idea. If I do a slotless motor it would be eaiser to integrate the blower.

I think I prefer no blower. Quieter plus a blower would tend to suck dust and dirt through the motor.

Sure I can add bell support bearing, but the additional hassle/wear/maintenance/cost/noise of a giant ring bearing may be better spent by just using a thicker bell. If anyone has documents on the stability of spinning tubes...that would be a huge help. It could be as simple as adding some sort of damper system to keep oscillations down?? Our airgap will be large enough in this motor to keep the magnets from colliding with the stator, but if there are any severe vibrations I'll have to go back to the drawing board.

Good. Its not the bearing I want. Its the necessary structural integrity.

 

[CNCAddict]

Had another idea guys. Rust is a big issue on my scooters/bikes. How about stainless shaft, bearings, and fasteners?? That would keep things looking shiny for a long time and add only a small amount to the final cost.

 

[recumpence]

Hmm, spiffy!

How about titanium shaft and fasteners? I know I would be willing to pay more for those.

Matt

 

[CNCAddict]

How about titanium shaft and fasteners? I know I would be willing to pay more for those.

Hmm, yeah so I'm not sure many other people would pay $50 extra for a titanium shaft to save a few oz Once we get the ebike craze to the same level of insanity as the high end mountain bikes, etc...then I'll make a motor from solid carbon fiber with bits of unobtainable all over and "250W max" written on the front in diamonds.

I'm really really seeing a lot of potential for the controller/motor on the bike and the batteries in the backpack. This makes the bike total weight probably identical to it's pedal counterpart since even my huge motor would weight about the same as the cranks/chainrings/shifters that are on a normal bike. Makes carrying it up stairs at universities all the easier. I would have killed for something like that when I was in school.

Yeah, so I've decided to go with scaled up version of the X-era 40 series. I've started the new design so there is no turning back now. I may do some things to reduce cogging, but there are 24 cogging pulses/rev of the motor. So in any deep gearing situation, this shouldn't be a big deal since things will smooth out at only a few mph. Also, it will keep the bike from rolling around at a stop which may be helpful...or a PITA depending on how you look at it. Also, the motor should work at any PWM you give it, and should produce a really clean BEMF signal unlike some of the other motors out there, so if you don't like the squealing just crank it up to 24khz. The OD will be a tad over 75mm, so I hope this won't be a big problem. Overall though, this should be an excellent motor and very efficient compared to many out there.

I will start making parts in the next month or so and will give some updates on my progress. The first test vehicle will be my 15s3p A123 scooter with the SHV250 controller (should be at my doorstep in a few weeks). I better start looking into a good set of riding gear. Anyone know the best deals on that sort of thing???

 

[MitchJi]

Had another idea guys. Rust is a big issue on my scooters/bikes. How about stainless shaft, bearings, and fasteners?? That would keep things looking shiny for a long time and add only a small amount to the final cost.

Sounds good to me.

Might be better to start a dedicated X-era 60 Series Thread in Ebikes Gen or Ebikes Tech.

 

[recumpence]

I just got off the phone with David (almost an hour).

We covered the majority of what is needed for a RC/E-bike motor and drive system. I think we have it pretty well ironed out.

I think it would be a good idea to start a new thread regarding David's motor and my modular drive system specifically. This thread can be left for general RC questions and what-not.

Here is the new thread http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=7180&start=0&st=0&sk=t&sd=a

Bear in mind, David does not have a completed motor to show you, nor do I have a completed drive unit to show. However, the new thread should be devoted to what everyone wants to know about our system/s and suggestions they have.

It looks like we will be able to "Work together" so to speak on this. David is more than willing to make the 60 series "The way I/we want it" for bike use and compatibility with bikes. That is truely good news! Now I can build a drive unit without the compromises I would normally have using existing motors.

Matt

 

[fechter]

But this thread is only 75 pages long... (an ES record I think)

I think I might need to create a whole forum category for RC stuff.
What do you think?

 

[MitchJi]

But this thread is only 75 pages long... (an ES record I think)

I think I might need to create a whole forum category for RC stuff.
What do you think?

Hi Richard,

I suggested that about 20 pages ago:
http://www.endless-sphere.com/forums/viewtopic.php?f=1&t=5616&p=84795#p84795

I think Miles had a better idea:

Mitch,

If we are going to have a further sub-division, I would prefer it to be between hub motor designs and non hub motor designs.

And so did Matt:

Good call.

There are so few non-hub driven bike compared to hub motored bike that it would be good (for now) to lump them together.

Matt

I think a non-hub driven forum would be a big improvement. I didn't know why it hasn't happened sooner (maybe because nobody [me for example ] called the issue to your attention).

Or maybe because there were almost as many opinions as there were responses to the suggestion :lol:

Thanks!

Mitch

 

[recumpence]

I think it is a good idea to make a sub-catagory too. I think it would be welcomed by hub guys as well because the RC and other non-hub style systems will not push the hub drive threads off the front page.

At any rate, I also feel like I am kind of to blame for alot of the forum clogging with these RC threads. I hate to muddy up the waters for any newbies who are simply looking for info on their WE system or Clyte motor, etc.

There are a few of us that can scout the non-hub (or RC) sub-group answering questions. I know there are a number of us familiar with RC systems who can do this. Heck, John is a mod. He can do the moderating for that sub-group.

Matt

 

[Miles]

Yes, now seems to be a good time to make the division. We could transfer/copy a few of the seminal threads over to the new section.

 

[paultrafalgar]

At any rate, I also feel like I am kind of to blame for alot of the forum clogging with these RC threads. I hate to muddy up the waters for any newbies who are simply looking for info on their WE system or Clyte motor, etc.
Matt

...forum clogging! FORUM CLOGGING!!!
Don't you dare stop your "forum clogging". Cyberspace is limitless - that's why it's call endless-sphere! Or is there a shortage of disc space?! At £80 per terabyte I DON'T THINK SO! Your contribution is one of the most valued here, Matt.
:lol:

 

[TylerDurden]

RC adaptations are the future of small EV's... Hub motors are not likely to evolve much from this point. IHMO

I was surprised to see this section split from tech, as the tech here is advancing more than hubbie tech.

Regardless, keep up the good work; we are reading with great interest.