Commuter Booster - <1kg Friction Drive

[hillzofvalp]

I'm willing to give it a shot cause I don't care about rain. There looks to be a safe 75mm down there. Please make recommendations on motor model (63-74 vs smaller). I will start on my road bike and probably use Lyen's sensorless controller should I choose a hub motor down the road.

Recommendations for mounting to bb axles? (square taper might work well. I know on conventional bottom brackets there is a little gap between the crank and bb cup.I would need to make an insert for a bearing to allow square taper, I guess.

If I were to have the motor mounted and ride in the rain with no motor power, would the motor sustain damage even if let to dry out?

 

[Hillhater]

If I were to have the motor mounted and ride in the rain with no motor power, would the motor sustain damage even if let to dry out?

Yes.. rust & grit in the bearings, rust on the shaft, magnets, can etc . Pretty much a death sentence.
Why would you want to mount it down there ?.. it would collect all the crap from the front tire as well as the rear, even in the dry.

 

[adrian_sm]

Update: Modify Watt Meter

Success. I now have the watt meter limiting current, and it appears to be controlling it fast enough. So no more ugly surging.

So many things to now test. I'll prove it further on the 6374 first to iron out of the bugs.
Then see if I can get the 50mm motor playing nice.

Pity I have used all of the available programming space. If I want to implement anything else, I will have to start removing other features, or optimising the existing code.

Oh well. It was only meant to be a short term solution, or one for the hackers out there. But I am pretty darned happy that it can do what it does.

- Adrian

 

[umejopa]

Nice you get it running Adrian
What was the problem with current signal to the uP ? Ok read that you have shunt back in place.
Latter cade i have update current evry 40mS . Did you still have slow down the code to get the LCD working ?
I waiting still for part from HK but they was in Sweden now so soon I can get it running again.

//Jonas

 

[adrian_sm]

Thanks Jonas. I couldn't have done it without you.

I still have the uC speed back to normal, not sped up like your code. From memory it was also affecting the PWM signal, not just the communication with the display. So I have left it alone since it is all working.

Funny. Just seeing it say "Commuter Booster" on startup rather than "Turnigy" or "GT-Power" still makes me smile for some reason.

- Adrian

P.S. Don't forget to PM me your mailing address so I can send you a thank you.

 

[adrian_sm]

Throttles & Interfaces

I had a PM asking about kepler's interface vs my hacked my watt meter. And thought I would share my reply for others to understand what the options are for controlling the friction drive.

The alternatives I can think of are:
1) servo tester throttle
- not advised
2) modified servo tester throttle
- for hall or button throttle
3) modified servo tester throttle + ramp control
- my minimum useable system
4) modified servo tester throttle + ramp control + CA throttle override
- tried and failed to get it to work, but should in theory with a standalone CA
5) modified watt meter
- shows promise for hackers, but may not be smooth enough, and still doesn't enforce a minimum speed
5) kepler's interface
- the mythical all-singing, all-dancing interface

John's interface will be awesome, but it is still in developement. I have ridden his bikes a couple of times with the interface, and I'll definitely be grabbing one when I can. The good news is that when he does release it it will be a fairly mature product, with a lot of testing and development behind it.

My Watt meter hacks, are hacks at best. Since I am a Mechancial Engieer, not a elec or software.
Having said that it does do a few key things:
- can suit a button, hall or pot throttle
- creates the necessary PWM signal for the ESC, without hacking a servo tester
- can perform ramp control of the throttle to allow smooth engage & disengage of the drive
- can now limit current. Hopefully this will help with protecting tire and motor
- gives basic battery and power readings.

The key new thing this does over the old servo tester & ramp control is limitting the current. But it is a crude current limit, and I haven't done much testing yet to see how usable it is. Only a couple of test rides around the block in the middle of the night.

Kepler's I believe do all of the above plus a whole lot more, in a refined and developed package. But you will have to pay for it. And rightly so after all the time & money he has spent on it. Key ones for me are :
- enforcing a minimum speed before you can use the drive.
- power profile settings
- nice display interface
- new button throttle logic
- plus a bunch of nice to have features, like powering lights, fuel guage etc.

If you are strapped for cash, can't wait or don't mind driving around some of the quirks of the friction drive there are cheap alternatives. But if you have the cash, and want a polished solution, Kepler's interface should be the best option for friction drives.

Hope that helps.

- Adrian

 

[umejopa]

Whats glue are you using to glue the grit belt sander material ?
/Jonas

 

[adrian_sm]

I used a contact adhesive. Selleys Kwik Grip

It is easy to apply, good shear strength, can be cleaned up relatively easily if the grip needs to be replaced.

I like it.

 

[rj7855]

I used a contact adhesive. Selleys Kwik Grip

It is easy to apply, good shear strength, can be cleaned up relatively easily if the grip needs to be replaced.

I like it.

Which is ofcourse not available here :-(
What about UGLU? ( http://www.youtube.com/watch?v=e7vJHWDhiXo ) I think it was mentioned here in this thread... but not going to dig thru 50 pages

 

[Kepler]

Yes, thats the stuff I use. I like it because the job is done without waiting and it is much stronger and thinner then double sided tape.

Kwik grip is just contact adhesive though. I am sure you can get another brand locally.

 

[adrian_sm]

Which is ofcourse not available here :-(
What about UGLU? ( http://www.youtube.com/watch?v=e7vJHWDhiXo ) I think it was mentioned here in this thread... but not going to dig thru 50 pages

I wouldn't recommend the uglu stuff. It is not the right shape, not very good in shear, and expensive.

You should be able to find a suitable locally available contact adhesive. I just went to the local hardware store, and looked for one that was suitable for metal, wood, rubber, laminates etc. and water resistant.

The contact adhesive are also easy to apply where you want them, and much more economical.

- Adrian

 

[adrian_sm]

Other news. I just put a hobby king order in, and bought all the available variants of 50mm and 63mm motors they had in stock around the right kV, a different ESC that has data logging, and a bunch of other odds and ends.

TGY AerodriveXp 160 SK Series 63-64 230Kv
TGY AerodriveXp SK Series 63-74 170Kv
TGY 63-54-A 250Kv Brushless Outrunner
TURNIGY 50-65D 270kv Outrunner
Turnigy Super Brain 80A Brushless ESC
Turnigy USB Linker for AquaStar/SuperBrain

This should allow me try out a few things.

Next will probably be LiPo of various voltages. Would be interesting to try out 6s again with current limitting, and 3or4s just for the simplicity of being closer to legal speed/power limits for ebikes in this part of the world. But I think it is cheaper to buy this from the Aussie warehouse. It will also get me closer to building a few full kits I can loan to mates.

The main reason I like 5s, is it gives a nice 43kph cruise for the 63-74, 200kV motor, and 4x5s5000mah packs fit perfectly in the Large Topeak Aero wedge bag I use.

- Adrian

 

[Hillhater]

Looks like you plan on having some fun adrian ! :wink:
but you should have saved your money on the 63-54 Turnigy... when you do the maths, it has a lot less torque than the 170kv motors and i have had a lot of sync issues with it also ..Pity, because it is a nice compact little motor.

 

[Kepler]

Which is ofcourse not available here :-(
What about UGLU? ( http://www.youtube.com/watch?v=e7vJHWDhiXo ) I think it was mentioned here in this thread... but not going to dig thru 50 pages

I wouldn't recommend the uglu stuff. It is not the right shape, not very good in shear, and expensive.

You should be able to find a suitable locally available contact adhesive. I just went to the local hardware store, and looked for one that was suitable for metal, wood, rubber, laminates etc. and water resistant.

The contact adhesive are also easy to apply where you want them, and much more economical.

- Adrian

I dont know what you did with the uglu Adrian but I have found it to be a great. Never had it fail. The belt sander material would wear out first. Bit on the expensive side. Works out about $1.70 per drive. Typically I want to apply the friction material and go out and test rather then wait over night for glue to dry.

 

[Kepler]

Other news. I just put a hobby king order in, and bought all the available variants of 50mm and 63mm motors they had in stock around the right kV, a different ESC that has data logging, and a bunch of other odds and ends.

TGY AerodriveXp 160 SK Series 63-64 230Kv
TGY AerodriveXp SK Series 63-74 170Kv
TGY 63-54-A 250Kv Brushless Outrunner
TURNIGY 50-65D 270kv Outrunner
Turnigy Super Brain 80A Brushless ESC
Turnigy USB Linker for AquaStar/SuperBrain

This should allow me try out a few things.

Next will probably be LiPo of various voltages. Would be interesting to try out 6s again with current limitting, and 3or4s just for the simplicity of being closer to legal speed/power limits for ebikes in this part of the world. But I think it is cheaper to buy this from the Aussie warehouse. It will also get me closer to building a few full kits I can loan to mates.

The main reason I like 5s, is it gives a nice 43kph cruise for the 63-74, 200kV motor, and 4x5s5000mah packs fit perfectly in the Large Topeak Aero wedge bag I use.

- Adrian

Plenty of testing to be done. Look forward to your reported findings. Do any of those motors have skirt bearings?

 

[adrian_sm]

Nope, don't think so. Will be interesting to see how long they last. Shorter stack should help reduce the moment, controlled maximum engagement will help, but I am sure most people will say they will never last.

They are only $40-50 each so no big loss, even if I just learn a bit about running at different kv's.

 

[ferias77]

Hi,

I am continuing to take information about friction drive, and there is an element I don't understand : the top speed.

If I don't make a mistake, with the 200 kV 63mm motor, the top idle speed under 5S is approximately 20V x 200kv x 63 mm / 1000 x pi / 30 x 3.6 = 95 km/h.
It is approximately the same with the 270 kv 50mm motor : 20V x 270kv x 50 mm / 1000 x pi / 30 x 3.6 = 102 km/h.

How is it possible that there is a ratio of 2 between the top idle speed and the top speed (43km/h)?

 

[adrian_sm]

Hmm. They way I calculate it is something like this.

Revs = Voltage * kV = 20v * 200kV = 4000rpm = 240,000 rev/hour
Circumference = Diam * Pi = 0.063m * 3.14159 = 0.198 m = 0.000198 km
Speed = Revs * Circumference = 0.000198 * 240,000 = 47.5 kph

 

[gtadmin]

Hi,

I am continuing to take information about friction drive, and there is an element I don't understand : the top speed.

If I don't make a mistake, with the 200 kV 63mm motor, the top idle speed under 5S is approximately 20V x 200kv x 63 mm / 1000 x pi / 30 x 3.6 = 95 km/h.
It is approximately the same with the 270 kv 50mm motor : 20V x 270kv x 50 mm / 1000 x pi / 30 x 3.6 = 102 km/h.

How is it possible that there is a ratio of 2 between the top idle speed and the top speed (43km/h)?

Shouldn't the 30 be 60 (circ = pi x D, not 2pi x D)?

 

[adrian_sm]

Updated Installation Template:

- Fixed seat tube diameters, msallest seat tube diameter to 28.6mm.
- added 100mm reference scale.

Please ensure when you print to force your printer to not scale the PDF. Most printers will try to scale to the print margins of you printer.
Commuter Booster - Installation Template.pdf

- Adrian

 

[ferias77]

Hmm. They way I calculate it is something like this.
Revs = Voltage * kV = 20v * 200kV = 4000rpm = 240,000 rev/hour
Circumference = Diam * Pi = 0.063m * 3.14159 = 0.198 m = 0.000198 km
Speed = Revs * Circumference = 0.000198 * 240,000 = 47.5 kph

Shouldn't the 30 be 60 (circ = pi x D, not 2pi x D)?

Oups, you are right... Thanks for the correction.

 

[rj7855]

Hmm. They way I calculate it is something like this.

Revs = Voltage * kV = 20v * 200kV = 4000rpm = 240,000 rev/hour
Circumference = Diam * Pi = 0.063m * 3.14159 = 0.198 m = 0.000198 km
Speed = Revs * Circumference = 0.000198 * 240,000 = 47.5 kph

So the 170kV motor you order should max out at 40.4 kmh.... that sounds perfect for me

 

[adrian_sm]

Remember these are the no-load speed calculations. So this is where the motor is not providing any useable power.

If you want to just go full throttle and cruise at about 40-43 kph, I would still stick with the 63mm 200kV motor, on 5s of LiPo.

- Adrian

 

[adrian_sm]

A few of the Alpha testers are wanting to mount the drives on bikes with different seat tube sizes. So I thought I would mention that I have happily mounted a 34.9mm CB on a 31.8mm seat tube, using a section of an old inner tube as a "shim". Worked really well.

- Adrian

 

[adrian_sm]

Reprogramming an ESC ???

A forum member asked me via PM if I planned to try reprogramming the Turnigy SuperBrain 80AESC I recently ordered. Wow, I never even thougth about it. Most of the basic functions I want don't need a display, so if I could do it that would be one hell of a neat solution.

It already has the ability to upgrade the firmware built in. But would require a fair bit of work to write new code, or reverse engineer the old, and add new functions.

I haven't received the ESC yet, but apparently it has the Silabs C8051F310 uC. I am not familiar with it, but looking at the spec sheet it looks pretty good. Heaps of memory space, lots of IOs. Well compared to the watt meter anyway.

Anyone with some skills to help out please raise your hand. I might just provide you with a CB Alpha kit for your troubles.

Actually I wonder if this is possible, or if people have already done it, for other higher quality controllers like a Castle Creations Phoenix Ice 100.... Hmmm.

- Adrian