Ebike Controller on Outrunner Friction Drive

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DeamEyes

100 µW
Joined
Jun 30, 2015
Messages
8
Location
Kenosha, WI
I previously bought an ebike kit with a direct drive hub. I have since made the change from a freewheel to cassette system and 6 to 9 speeds on my bike and am no longer able to use the motorized hub I had. I know I can get a motorized hub from ebikes.ca that is 9 speed compatible, but as I use my bike usually as just a bike I am curious about building a friction drive system like the commuter booster and eboost, or EVTodd's. My goal is the system could reach 25-30 mph.

I have 2 24V 10ah starkpower deep-cycle batteries I would like to use in this project. I also have a 48V 1000 watt controller that runs without the hall senors connected I would like to use on this project. Can I use this controller on an outrunner, and If this so any idea what outrunner motor(s) would be best suited? I know to look for low kv. Is it right to assume I should look for similar voltage and wattage that is higher than my controller is able to produce?
 
Well I've done quite a bit of reading on here (and much more remains). I've read both of EVTodd's builds, Spinning Magnets build, Most of the way through Keplers', and although I've perused it, I'll be reading Adrians' commuter booster thread next.

I decided to buy a Turnigy Aerodrive SK3 6374 192KV motor. From posts I've read (http://endless-sphere.com/forums/viewtopic.php?f=2&t=23882) it seems using an ebike controller is feasible, but one way to find out for sure. My plan is to essentially build a rubbee, but with more range/hopefully higher speeds. Depending on whether the drag from the motor is unbearable or not will dictate whether I borrow the swinging design Adrian and Kepler have demonstrated.
 
Good to see someone understanding how cheap it can be to build a friction drive and not paying the insane prices these companies are trying to charge.

I've been wanting to try a cheap sensorless controller myself but I haven't figured out if they can handle the high rpms you need with a friction drive and an outrunner. I've had great luck putting thousands of miles on Castle escs on my bike and the super cheap Mystery esc on my wife's. I will say that it's nice to have such a small controller you can hide anywhere.

As for your voltage and motor choices... If you plan on using the can of the motor, which it sounds like you do since you mentioned Rubbee; at 48 volts you'll have a no-load top speed of 63 mph (at 9216 rpms) with that motor! Actually, it would be higher if you make a roller to go over the can like Rubbee has. I would look for something with a much smaller can or much lower kv. Well, actually, I would run a separate roller but don't get me started on that. :lol:

You'll want to make sure your sla batteries can handle the amp draw these little outrunners can pull too.
 
I'm glad to see replies from the friction drive experts. Thanks for the advice so far.

63 miles (~53 going by the 85% estimate for no-load) does sound a bit much. I went with the larger motor as it was the closest to the max voltage of my controller and hopefully won't smoke it testing this out. Depending on initial tests I may implement a roller, but will stick with either a stationary or swing arm rig. I have nothing against the sliding mechanism; swing arm just looks a bit easier to construct/copy (even after reading Spinning Magnets' tutorial on building a sliding rig.)

The batteries are Lithium, but designed to replace SLA batts

My setup will be 2 24 volt batteries connected in series and according to the specs has a max draw of 15 amps. According to an online calculator I would need ~21 amps for 1000 watts at 48v. I'm not sure if this will just limit my max torque or the battery management system will just cut the power (I'll find out eventually).

The controller has a pedelec option and I'm planning on using that rather than the throttle once initial testing is complete.

I'll more post once the motor arrives.
 
You won't see anywhere near that speed on a real world setup and you shouldn't anyway, it is a bicycle after all. 15 amps will be nowhere near enough for this combo, especially if you use the can of the motor as the roller. I would reconsider that voltage and battery choice. It just doesn't match up to what you're trying to do. I also doubt that motor will last long at that voltage which is higher than it's rated for. Outrunners get pretty hot even when using them as intended. At 48 volts you'll probably have a lot of problems with magnets getting loose.

As for a swinging or sliding mount. You can get by without it but you'll need to have quite a bit of pressure on the roller all the time so it doesn't slip. It doesn't seem like a little outrunner would be that noticable but it's really annoying after a while if you ever want to pedal it like a normal bike.
 
Well you are best suited for advice as your setup is what most closely matches my specs. As I stated in my original post I'm hoping for a drive that can achieve 25-30 mph max speed.

On the old commuter booster page Turnigy Brushless ESC 85A is listed. Does this seem suitable for my purposes, or would it be safer to look at something with higher(100) amps? I do intend to use this drive once the bike is in motion, so based on what I've read so far the 85 seems right, but I am an RC motor novice. Are there any other data points I should look at for an ESC aside from amps?

If I remember correctly, you used powertool batteries on your setup. Do you know what your battery setup was in volts/amps/Lipo S equivalent is?
 
DeamEyes said:
Well you are best suited for advice as your setup is what most closely matches my specs. As I stated in my original post I'm hoping for a drive that can achieve 25-30 mph max speed.

On the old commuter booster page Turnigy Brushless ESC 85A is listed. Does this seem suitable for my purposes, or would it be safer to look at something with higher(100) amps? I do intend to use this drive once the bike is in motion, so based on what I've read so far the 85 seems right, but I am an RC motor novice. Are there any other data points I should look at for an ESC aside from amps?

If I remember correctly, you used powertool batteries on your setup. Do you know what your battery setup was in volts/amps/Lipo S equivalent is?
Click to expand...

You probably already read my thread but my bike is currently running 10s lipo (previously used 36v Bosch Fatpacks) and a TowerPro 5330 motor (no long made) and a 1.25" roller. That gives me a no-pedal top speed of 28+ mph or around there.

You might be able to get by with 48 volts if you use a small roller. Maybe... I just don't think most of these outrunners can go much over their rated voltage. My big concern is using the can of the motor on a setup like this. Commuter Booster and all of the "drive off the can" motors are a much different beast. Most of those are running or 6s lipo if I recall. Truely an assist only drive which is fine but just different. And nope, that esc won't work for your batteries. It's only rated at 6s max.

The esc I use is a Castle Creations HV85. I've had great luck with it. I did finally let the magic smoke out of one a couple of years ago when I was beating the hell out of it and paid the price. lol. There are starting to be some less expensive "HV" esc's out there that I want to try once I pop my current esc but without trying them I can't recommend them. My wife has been using a super cheap "mystery" controller on her 6s friction drive for several years.

I would personally try a 1" roller with the setup you currently have. That would get you around the speed you want. It might be interesting to find out how many amps that would draw. It might not be that bad at that voltage. I really don't know about the sensorless controller. I can't seem to find anyone on here that knows if they can handle the high rpms.

I will say though that there is a bit of a safety concern when you have a roller spinning that fast. Make damn sure it's secure. I wouldn't want to see a roller flying out of a bike at that speed. I think that's something people don't consider with friction drive. Especially the people trying to market them.
 
Yeah, after my post I realized I'm mixing apples with oranges. Perhaps creating a rig that uses a roller, but engages on a pivot is the middle ground for this project.

I'm not against investing in a RC ESC and some 10s lipos (it'll cost less than the batts I have); its just a shame I don't have any use for the batteries I already have. I could try selling my hub kit with batteries, but thats another topic. How many 10s do you have in your setup and do you have an estimated range?

I did find this controller. It comes with a rpm sensor, which may come in handy for detecting slippage when I get to the stage of making a semi-sophisticated throttle still need to read thisthread. High voltage and 100 amps. Obviously everything done is at my own risk, but any obvious reasons this setup would not work?
 
I finally got the cables soldered together to try the ebike controller on the outrunner. The motor runs in a very jerky fashion, but as its a motor the controller was never meant for I can't bee too surprised.

I assembled a pivot mount that I'll be loctite-ing all the bolts on, waiting for the parts to assemble the roller.
Moving forward I'll get a RC ESC capable of 100 amps just to be on the safe side.

As for 10S batteries would 25C be enough?
Also EVTodd, what adhesive did you use on your outrunner magnets?
 
DeamEyes said:
I finally got the cables soldered together to try the ebike controller on the outrunner. The motor runs in a very jerky fashion, but as its a motor the controller was never meant for I can't bee too surprised.

I assembled a pivot mount that I'll be loctite-ing all the bolts on, waiting for the parts to assemble the roller.
Moving forward I'll get a RC ESC capable of 100 amps just to be on the safe side.

As for 10S batteries would 25C be enough?
Also EVTodd, what adhesive did you use on your outrunner magnets?
Click to expand...

I use a 2 part epoxy. Look at the packaging and find the one that has the highest temperature rating at your local hardware store. It seems like the slower the cure rate the higher the temp rating. I would say about once every two to three years I have to re-glue one magnet. I've seen a lot of talk about using super glue. I just don't see that holding up very well.
 
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