Using RC motors on E-bikes [Archive]

[swbluto]

There's going to be "should be negligible" unaccounted for errors like motor overheating and magnetic field saturation from too much current. :wink:

Armature temperature is certainly something you need to account for.....

Hehe. I guess someone as uneducated as I shouldn't be developing this.

(I'm not really knowledgeable about all of the "inner workings" of motors which seems kind of ironic. How does armature heating affect the motor? I suspect it'd increase the resistance of the "armature" which I suspect carries the current to the windings which decreases the drawn amount of current? Oh well, if you have a mathematical formula of some sort, I could integrate it. It'll probably make the program more complex, but default values can be used for those additional parameters which shouldn't bother the majority of "default users".)

 

[Miles]

Temperature coefficient of copper is 0.4% (0.393%) per degree C. So, for a 30 degree rise in winding temperature, the resistance will go up 12%.

Most of the motor calc. programs have an input for the weight of the motor and use a nominal power dissipation per unit weight figure, I think.

I certainly support the idea of a combined motor/bike performance calculator

You could play around with these ones:

http://www.drivecalc.de/

http://www.micronradiocontrol.co.uk/scorpion_calc.html

http://www.endless-sphere.com/forums/viewtopic.php?f=11&t=538&start=2

http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=1062&p=16691#p16691

 

[swbluto]

Ok, thanks. I'll look more into that.

For now, I got the "beta" version programmed and it's now running(It's mostly imperial units but adding on metric-friendly units shouldn't be difficult: It just takes time to implement which should take about... 2-4 hours if I get around to it.)! It's a java applet so it can be used directly from the browser. For now, I just need to find a server to start a website and snatch a domain name(any suggestions, anyone?)! And... I'll use this website for many different things which I could present to my future employers/professors/whomever, which will make a nice addition to my "portfolio.".

Once I get it hosted and everything, I'll start my own official thread on e-Bike Technical looking for "beta testers", so to say(haha.) and I'll also ask for feature requests. For now, it just finds the final velocity, but I could output a variety of things like final power, battery current, efficiency, etc. I could perhaps graph things if I can somehow integrate graphs into Java Applets.

 

[paultrafalgar]

Well done, Bluto, keep it up!

 

[TylerDurden]

Some charts are scripted in flash:
http://finance.yahoo.com/charts?s=G...=on;ohlcvalues=0;logscale=on;source=undefined
(cut and paste... BBcode don't like the parameters)

It looks like Justin is using a custom external .js for the simulator:
http://www.ebikes.ca/simulator/

		<title>ebikes.ca Hub Motor Simulator</title> 
		<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 
		<script type="text/javascript" src="local/webfxlayout.js"></script> 
	    <script type="text/javascript" src="includes/excanvas.js"></script> 
   	 	<script type="text/javascript" src="includes/wz_jsgraphics.js"></script> 
		<script type="text/javascript" src="includes/chart.js"></script> 
		<script type="text/javascript" src="includes/canvaschartpainter.js"></script> 
		<script type="text/javaScript" src="includes/aesthetics.js"></script> 
		<script type="text/javascript" src="includes/motor_sim.js"></script> 
		<script type="text/javascript" src="includes/motor_specifics.js"></script> 
		<script type="text/javascript" src="mybic.js"></script> 
		<script type="text/javascript"> 
		<!--

 

[MitchJi]

Hi,

For those who haven't seen it Matt posted a nice comparison of the issue of outrunners versus inrunners here (well worth reading):
http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=6475&st=0&sk=t&sd=a&start=60#p102335

One thing he said was:

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 emailed Hacker tech support and asked about this issue with the A60L:

Please take a look at our A60 motor mount
http://www.aero-model.com/mmdetails.aspx?id=A60-MM

We suggest all A60 motors be used with this motor mount ($24.99). This will eliminate the vibrations and flex.

I'm not sure if that solves the issue or not. If there is an inner bearing at each end of the motor I think it will. If anyone is sure one way or the other please post a response.

BTW he also said:

Max watts for the A60L motor is 2600W for 15 second bursts.

The continuous will be around 1800Watts. We rate these motors pretty conservative so when using an amp meter the motor may produce more power.

Would it be possible (and affordable) to use a Plettenberg EVO on an Ebike by using a similar mount? Maybe a modified version of the Hacker Mount?

The back of the Plettenberg could be bolted to the front of the Hacker Mount and the bearing on the Hacker Mount could be changed to a bearing that fits the Plettenberg prop shaft. Would this work?

A $275 Plettenberg with peak power range up to 3.5kW seems like an attractive proposition if it can be made to work well on an Ebike.
http://www.icare-rc.com/plettenberg_xtra30evo.htm

Thanks!

Mitch

 

[recumpence]

That mount does not address the skirt flex issue at all. It is just a shaft flex reducer.

How about one of these new motors?

http://www.rcgroups.com/forums/showthread.php?t=929348

Matt

 

[MitchJi]

That mount does not address the skirt flex issue at all. It is just a shaft flex reducer.

How about one of these new motors?

http://www.rcgroups.com/forums/showthread.php?t=929348

Matt

Hi Matt,

I thought the mount might not address that issue. Thanks!

I don't know enough about RC motors to know if its a good choice or not. The weight, power and price look excellent. If you recommend it and if it fits your "simple belt drive" I am very interested.

Two potential show stoppers:

• Kv :: 500
  also with this heli, most of the motor sound is from the hacker A30 on the tail.

Watching the beginning of the movie it looks like most of the noise is coming from the tail. I hope so because it sounds pretty loud.

Posted by Matt on ES:

The only issue (problem) with high RPM RC inrunners is the high pitch whine they emit. The planetary gearbox adds a bit to this.

The noise you mentioned was the main factor in deciding to skip the Neu. The X-era you are suggesting has comparable Kv.

Posted by Matt on the RC Forums:

So, how about a motor in the 400 KV range (maybe even lower)?

I am looking for 20,000 RPM or under on 12S. I run a belt drive and belt drives require sub 20,000 RPM to operate at low drag.

Matt

My preliminary calculations are that with the 149Kv Hacker I would need about 16.5:1 (I plan to post my figures to see if I'm correct when I get a little further along). If my figure is correct with the Hacker with the X-era you are suggesting I would need 55.3:1

Might require a planetary in front of the belt?

Its definitely an interesting possibility.

Reducing the above to one sentence if you recommend it, if it fits your drive, if it isn't too noisy and I can deal with the required reduction I want one.

Thanks for the information!

Mitch

 

[recumpence]

I am currently in communication with David (the motor importer) about this. He is also an EV guy and has read this thread. He mentioned wanting to make a 60 series motor like the one in the RC Groups thread. That would be excellent!

I will keep you posted.

Oh, most noise in that video is not the motor, but the gear drive.

Matt

 

[Jason]

I'm currently in the works on finishing my rc motor giant mountain bike setup. The motor is a Turnigy sk 380kv 50-65 with a castle hv85A controller. The batteries arrived last week and unfortunately ups must have been throwing them around because one of the cells had chipped off a corner leaking lithium goo into the box. Anyhow my replacement batts should be arriving tomorrow so I can see where I'm at with 29 Volts and 40AH (The thundersky bike package). Currently I've been doing some testing on the motor and speed controller with a 12 Volt car battery. I'm actually pretty surprised with the power of the motor using a 20/1 reduction through belt drive (Golden eagle HTD pulley with 12 tooth on motor). The first time trying it actually wheelied and ran into the wall pulling out my connections as I tried to hold it with my free hand while the other was on the servotest/wattmeter. So far the motor seems rather quiet and smooth with almost no whining. I ran the motor for sometime while pulling the hand brake for drag to load the motor at around 600watts. It pulled fine and the temperature never got more than slightly warm to the touch. I look forward to finishing it up this weekend and seeing how it handles myself at 275lbs. I also noticed that hobby city now has a turnigy sk 170kv 63-74 rated at 3250 watts for $83.00 seems like a steal and a great possibility for an ebike project maybe even my own if I find that I want some more torque. Anyhow I'll update with more after I get a chance to ride it this weekend.

 

[voicecoils]

.

Awesome! There are a few things I'm curious about if you get the chance:

How many amps can you pull from the thundersky batteries?

Where did you get the large pulley that attaches to your spokes?

Can you post some detailed pictures of it and describe the material it's made of and how much power/torque you think it could handle?

 

[Miles]

Where did you get the large pulley that attaches to your spokes?

http://www.bikeengines.com/orderpage2.htm

 

[voicecoils]

Where did you get the large pulley that attaches to your spokes?

http://www.bikeengines.com/orderpage2.htm

Cool. Are they the only ones that have made such a product?

 

[Miles]

Cool. Are they the only ones that have made such a product?

http://whizzermotorbike.catalog.com/browseGroup.cfm?item_group_id=48792

 

[paultrafalgar]

Miles, is there a freewheel mechanism attached to the motor of these systems? Otherwise, you have to pedal the motor round when you are not using it? Is that the case? And would it be feasible to make a 20" wheel version (say 16" drive rim)?

 

[Miles]

Paul,

You could certainly use a one-way clutch bearing on the drive pulley - you'd still have the losses from the drive itself, though...

Yes, you could use a smaller rim as a toothless pulley - it used to be a common method.

 

[Jason]

I recieved the battery today, but unfortunately have to go to school tonight. I am using a one way drawn cup roller bearing for free wheel, but it seems to be unable to hold up to the torque of the motor (slips on take off and heavy load). I may just end up taking it out and buying a new pulley that will fit the shaft directly. Since I have a spring loaded belt tensioner if I really just want to ride I can easilly remove the belt from the pulley and tie it up away from the wheel.

 

[Jason]

I did some load testing on the batteries tonight to see how they would do. I could only get to 55 amps before my one way bearing would start slipping, but under that load I was seeing a drop of around 1.5volts. I had no cut outs and the system ran pretty well. The pack sits at 27.4Volts fully charged. As far as the motor goes I'm even more impressed with higher voltage going to it; however the higher voltage has made the ringing and noise a bit more apparent. The belt drive didn't slip at 55 amps, but I'm going to have to order a regulaur htd pulley for the motor shaft and ditch the one way pulley if I ever want to ride it.

 

[skydog]

This may not be the right place to post this or you may have already discussed it but...

http://www.carbondrivesystems.com/

Finally a factory produced high torque drive system for bikes. I think this would be particularly cool with RC type motor and one of the internal hubs.

 

[MitchJi]

Hi,

I did some load testing on the batteries tonight to see how they would do. I could only get to 55 amps before my one way bearing would start slipping, but under that load I was seeing a drop of around 1.5volts.

The belt drive didn't slip at 55 amps, but I'm going to have to order a regular htd pulley for the motor shaft and ditch the one way pulley if I ever want to ride it.

Are you sure there isn't a one way or freewheel that will take the torque? Scott Clarke used a one way on an RC system with peak watts of about 2.8kW (your A40 is rated for 1100 peak watts) and didn't report a problem.
http://endless-sphere.com/forums/viewtopic.php?f=3&t=5156
http://endless-sphere.com/forums/viewtopic.php?f=6&t=5168

This may not be the right place to post this or you may have already discussed it but...

http://www.carbondrivesystems.com/

Finally a factory produced high torque drive system for bikes. I think this would be particularly cool with RC type motor and one of the internal hubs.

If you want to use it between the pedals and rear sprocket it might be fine. For use with an RC Motor there are at least three issues:

• 
  Very limited selection of sprocket sizes
  
  Very limited selection of chain lengths
  
  A belt drive system designed for about 100 RPM probably won't handle the high RPM of RC Motors.

 

[recumpence]

I have used oneways in helis before with good success.

Much depends on the shaft material and diameter.

Matt

 

[Jason]

The bearing I used was probably for RC helicopters since I got it from the same hobby store I bought the motor from. I think my biggest issue is the 6 mm shaft of the motor I don't think it allows for enough surface area for the amount of rollers needed to deal with the torque. I did some reworking of the motor mount and tensioner system this weekend. I moved the tensioner lower to get more belt contact and added a different front and rear bearing support with some oversized abec 5 bearings I had sitting around.

 

[MitchJi]

Hi Jason,

It might be best to start a build thread.

Can you use two oneways fastened together?

 

[CNCAddict]

Hey guys, I designed the X-era motor and I'll be working on something for extremely fast EV's. If you all have any suggestions as to what is necessary for this motor, I would love to hear it. 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). 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. Again, I haven't designed anything on this motor yet...so now would be the time to pile on what you want this motor to be. Things like shaft size, shaft length, material, bearing type, max OD, max motor length, hall sensors or no, etc. is up in the air at the moment. Also, my target price range is ~$400, so it can't get too fancy

P.S. I'll be targeting the Castle SHV250 control since I love Castle products and it will include data logging, and direct hall interface (on the industrial version)

David B.

 

[voicecoils]

Hey guys, I designed the X-era motor and I'll be working on something for extremely fast small EV's. If you all have any suggestions as to what is necessary for this motor, I would love to hear it. 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). 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. Again, I haven't designed anything on this motor yet...so now would be the time to pile on what you want this motor to be. Things like shaft size, shaft length, material, bearing type, max OD, max motor length, hall sensors or no, etc. is up in the air at the moment. Also, my target price range is ~$400, so it can't get too fancy

P.S. I'll be targeting the Castle SHV250 control since I love Castle products and it will include data logging, and direct hall interface (on the industrial version)

David B.

I'm totally stoked to hear this.

Having a motor that can handle the current in those situations you mentioned is KEY. Having a high RPM opens up the opportunity for a high top speed too. Your target weight sound very good. 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. It's nearly 12kg in a finished rear wheel Check my "DH Team build thread" to see where I'm at.

I'll think more about this and see what motor design/characteristic suggestions I can come up with.

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