New Friction Drive Project

[PhiloWaddell]

Hi I have posted before but didn't really have any clue what I was doing. Now I have a bit more of an idea so was wondering if you could help or point me in the right direction on the forum.

Okay, so I'm palnning on building a friction drive. Lots of 3D printed parts and stuff and these are the four motors I am looking at:
- http://tinyurl.com/turnigy243w
- http://tinyurl.com/turnigy336w
- http://tinyurl.com/turnigy575w
- http://tinyurl.com/turnigy830w

I know some of the seem a little underpowered but the law in the UK states that the maximum continous output for the electric motor must be less than 200W so my hands are tied there. If you think I'll be unable to get any 'umph' out of the puny 200W I'm allowed then I guess I'll just have to go for a bigger motor.

Also, I know I need an ESC but I dont want it to be radio controlled at all, I understand that the ESC will depend on the motor but what would you reccomend if i wanted to automate the throttle though some sort of IC chip?

UPDATE

Do I need a servo tester to run the ESC?

Thanks

 

[windtrader]

Friction drives are a niche here but there is solid past projects that have created some great outcomes. FD need a RC motor, ESC, throttle, and batteries. Servo testers basically server as the throttle. Search around and you can find stuff that works, most pretty similar. The way the motor drives the tire is more interesting as there are a few different ways to do this. Again, start researching and you will find the bulk of work done in this area from 4-5 years ago here on ES.

 

[PhiloWaddell]

Okay, so some of you may be aware Im trying to build a friction drive and I was wondering, if I decided to deactivate the motor but it was still engaged with the wheel and I continued to pedal (essentially turning the motor when it was powered down) would that damage the brushless motor or the ESC?

Thanks

 

[Hillhater]

That would depend on the controller you are using.
Some would let out smoke, but the right controller could act as a generator or even a Ebrake.
It would certainly make pedalling harder. ,!

 

[spinningmagnets]

Its my understanding that RC ESC's have not done well with this, but...I don't know about the drives that added hall sensors to the RC outrunner and used the common 6-FET E-bike controller.

 

[fechter]

It won't be a problem with most controllers. It's the same thing as coasing with the throttle off.

 

[kolby]

One of my ESCs has some resistance, the other can actively freewheel, so the motor spins without resistance (Heli ESCs seem to have freewheeling settings).

 

[PhiloWaddell]

Okay, thanks to all of you for your help. Kolby, which of your ESC's lets the motor actively free wheel and what RC model feature is it that allows it to do that? (for example would it be 'throttle signal loss protection' that allows it to do this?)

Thanks again for all your help!

 

[kolby]

This one has a setting called active freewheeling:
https://www.hobbyking.com/hobbyking/store/__42763__Hobbyking_YEP_120A_HV_4_14S_Brushless_Speed_Controller_OPTO_EU_Warehouse_.html

 

[amberwolf]

The only issue I can foresee is that if you begin riding or coasting fast enough that the motor speed is so high that it genrates a voltage higher than the FETS or caps can take, it could blow them up.

This has happened to at least one skateboarder here on ES; there's a thread from last month or two about it.

 

[fechter]

I remember one setup where they used a freewheel between the motor shaft and the drive roller. This would solve the problem for sure.

 

[PhiloWaddell]

Okay, so I have scrapped the free wheeling idea and have gone and ordered some kit.

This Motor: http://tinyurl.com/turnigymotor
This ESC: http://tinyurl.com/hobbykingesc60a
This Servo Tester: http://tinyurl.com/turnigyservotester

I'm looking at this to power it all: http://www.batteryspace.com/lifepo438120pbattery32v40ah128wh100arate.aspx

Would that be okay? Or is the voltage too low? Bearing in mind I'm only ever running this motor upto 3500rpm beacause thats the relative mps I need from the bike.

Thanks