friction drive ebike r/c motor

[willywatts]

hi everyone! im new to this so id really appreciate any help I can get! im trying to make a friction drive bicycle with an rc motor. here are the parts I am using below.

270 kv motor http://www.ebay.ca/itm/N5065-B-KV270-outrunner-brushless-motor-RC-airplane-Free-Shipping-/170880208162?pt=Radio_Control_Parts_Accessories&hash=item27c9410d22

100A ESC
(2x) 11.1v 5000mAh 20C lipo. used in series to create 22.2v 5000mAh pack
servo tester as throttle

in total with my bike the weight is only about 180 lbs and for some reason its not pushing me I haven't programmed the esc yet could that possibly be it? also to create more friction I wrapped the motor in skateboard grip tape. if anyone has any suggestions at all please let me know I could really use some help to get this project rolling thanks!

 

[spinningmagnets]

Does the motor spin the wheel when its in the air and unloaded?

The 50mm diameter motors have worked well for some builders with relatively flat land, but if you try to tackle any hills, you have to watch the motor heat, they can get very hot quickly. The larger 63mm motors have more copper mass, but the larger diameter means you need a lower kV to keep it from bogging down. I seem to remember Aeolian having a 63mm motor in a 170-kV, if the smaller motor doesn't work out. If the 50mm works for you, don't worry about it.

The 100A ESC is the right size.

Whats your commute like?

 

[rearengine]

Willy...We need A little more info ... You say it doesn't push you .. Just what does it do , what kind of noise do you hear.. ? is it slipping on the tire ? .. It's a good idea to peddle to about 8 mph before using the motor... Should program the ESC.... I'm useing a 6364 280 kv set up kind of like yours ... Bill

 

[willywatts]

the motor is not slipping at all. its making an inconsistant motor speed noise if that makes sense. i pedal before i start the motor, what would i program the esc to? i have an esc program card to make it easier

 

[willywatts]

my commute is fairly flat with a few low grade hills. would you reccommend that i make a roller for the shaft of the motor and use that?

 

[rearengine]

Willy ... Sounds like the motor is out of sync ... have you used the card to sync yet ? Could help if you ran on a roller I guess... It would have more low end toque & run at higher rpm, RC's like that ... Also a little slip on the tire when powering up is not all bad...You can loose a lot of efficiency if to tight on the tire... Hope you get things worked out.. Good luck with it ...


Hi to Spinner on post above... How's things??

 

[def215]

its nice to see more friction drives popping up.

one question, what brand of esc are you using? what you are describing does sound like sync issues as rearengine said. ive always used mystery brand esc's and they worked fine. then i switched it up to a dynam and i had sync issues, which caused a crash for me.

 

[spinningmagnets]

Hey Bill...the last two months my life has gotten a complete makeover, pretty much all good news! A far cry from renting a room on the cheap side of town for $200 a month a couple years ago.

willywatts, If an RC motor starts to bog down, it can "lose its place". Its called "losing sync", and it makes an ugly noise while you are sensing a sudden loss of power. The motor is brushless, so the ESC determines precisely where each magnet is located (while its spinning) by sensing the magnetic pulses. I've heard it called "back EMF" but I don't really understand the physics of it. I'll bet getting a Castle Creations ICE-100 ESC will fix it.

You can raise the volts to get more power so it will bog down less (which may require getting a motor with a lower kV), or get a motor with a larger diameter (which will give the rotor more leverage). You will never find a friction drive as small and light as a motor-shell drive like Kepler and Adrian (and your build). If you are content with 22-MPH, I believe the Aeolian 63mm diameter motor with a low 170-kV using 6S LiPo (22V) has a lot of satisfied customers.

If you use a separate roller (like I do) you have a lot of options. My generic Chinese 120A ESC had a loss of sync often. The Hobbywing 70A had a loss of sync under hard acceleration at 22V but not at 37V, and my Castle Creations ESC never had a loss of sync at any voltage under any conditions. The Castle ESC has a more sophisticated electronics filtering capability using high-quality components, but it is more expensive.

I experimented with differently priced ESCs to see what is the cheapest that would work for my application, since I wanted to sell a few (no longer trying to sell any). If you only want one friction drive build, save a few bucks up and just buy the Castle ESC. For a motor-shell drive, get a 100A model, if the roller is separate from the motor a 60A is adequate.

If you have the roller as a separate part from the motor, the drive will be larger, and more complex, but...a one-inch roller with a 63mm motor has a dozen different options (kV from 170-295), and is a great hill climber at 37V.

If you are interested, you could mail me your kit and $150 (I want to buy a CycleAnalyst), and I'll send you my prototype (I'm keeping the V2 in the build-log), it has a 1-1/4 inch roller and a Castle Creations ESC that will run 18V (5S) up to 28V (8S). It would also include a throttle cable, a servo-tester to use as a throttle, and extra input capacitors. I have a spare 63mm 250-kV motor to go with it that should provide 15-MPH at 22V...and maybe 22-MPH at 28V.

If you buy a 295-kV 63mm motor (like the one I have from Exceed), 28V should get you 24-MPH. If you want to go to 37V-44V, you'll need a different ESC.

 

[HumboldtRc]

Here is my friction drive Bmx. I fried 3 or 4 motors, the sk 6374 190kv's and 149kv's. I never got much sync loss, unless I tried to get on the throttle really fast. I've tried an HK150 esc on it and it worked fine. Then I tried a 160A HV dlux esc and the Bmx went 47mph top speed but you could only do one full throttle pass before the motor would be 300 F, and about to fry. I was pumping 5400 watts in to the esc about 120amps 45volts. I could hold the throttle about 2/3 open and go 42mph at around 2800watts, I could then give it full throttle and watch the watts go up to over 5000, and barely accelerate any faster. Which means about 2600 watts were going into making heat and not torque.

 

[Hillhater]

You have not said which ESC you are using, so we cannot suggest any program settings other than generic, such as set a slow throttle ramp up, and a sensible max current ( <75A maybe to start).
Also, get a proper throttle as using a ST is not helping.

 

[rearengine]

Willywats ... I am using the HK 100-120A DLUK ESC , works fine at 18-20 volts ... Thier is a 160A , or maybe it's 180A... They are very easy to program, and the price isn't bad... Hope your up and running... Bill

 

[willywatts]

http://www.ebay.ca/itm/TJET-100A-Brushless-Motor-Speed-Controller-RC-ESC-w-BEC-/261007505208?pt=Radio_Control_Parts_Accessories&hash=item3cc5427738 this this the esc I am using. would you suggest another one. and what would I need to program it to to make it work for me?

 

[Hillhater]

I doubt that anyone has run the same combo of motor/ ESC/ pack voltage, so finding a proven ESC program setting is unlikely..beyond the generics i already mentioned...low throttle ramp, & max current limit. PWM setting is anybodys guess.
Also, most Ebiks using ESC's fit a bunch more caps to prevent early failure.

 

[spinningmagnets]

Heres a $2 capacitor that most around here are happy with, perhaps add one or two as cheap insurance to save your ESC from high voltage ripple?...

http://www.digikey.com/product-detail/en/EEU-FM1H102/P12393-ND/613754?cur=USD

 

[willywatts]

what does this capacitor do? and how/where do I install it? im kinda new to this sorry lol

 

[willywatts]

and can I/ should I use a higher rated esc for my motor? why?

 

[spinningmagnets]

The Castle Creations ESCs have data logging, so the various kits have had their personalities recorded. An ESC was designed to run a motor at a fairly constant RPM, lots of airflow, and the RC lanes are fairly light so they accelerate quickly. A motor shell drive needs about a 100-amp capability (that means it has around 130A peak survivabilty)

On an E-Bike, they bog down a little, and they don't have the airflow because we run them sideways and usually behind the body of the rider. On an RC plane they are lengthwise and out at the nose. When they bog down two bad things happen. The ESC sends more amps to try and get the motor up to speed, and since it takes a long time for a bike to finally get up to speed, its sending high amps for much longer than it was designed to take. Amps = heat.

The other bad thing is when its struggling to get up to speed on an E-Bike (normally RC planes accelerate very fast) the amp-flow is being chopped and its kind of "springy"? leading to voltage spikes (I'm certain I'm explaining this wrong). Adding one or two capacitors helps.

A capacitor has two bare wire leads coming out of it, one will be marked as positive, and the other negative. Simply solder the leads to the red/black inputs to the ESC, somewhat near the ESC body. It acts as a voltage sponge and smooths out the pulses. Heres a pic of how Castle adds 4 extra caps to their RC helicopter ESCs. (also, skim the pics in this thread: http://endless-sphere.com/forums/viewtopic.php?f=30&t=22194)

http://www.castlecreations.com/images/gfx-cccappack/images/cccappack227_06.jpg

 

[willywatts]

so does anyone recommend I get a different esc? so that I can program it easier