Help me with a friction motor to choose

PLS help me to buy a good friction motor.

I'm brand new in this field, and would like to make a nice friction design.
I would like to have as much power as possible (since there are BIG hills around me), but most of the time I would use the motor for cruisin' in the city (mostly flat), but I like speed as well

My possible motors are:
http://hobbyking.com/hobbyking/store/__678__673__Electric_Motors-50mm.html
I know if the Kv is higher it spins faster, so I can get a higher max speed.
But the 580 Kv is probably too high (NTM Prop Drive 50-50 580KV).
The 2665 W (NTM Prop Drive 50-60 Series 380KV) could be reached on 30 Volts and the above one have the 2000W on 22.2 Volt, the same as this one on 22.2 Volts
Or this one(NTM Prop Drive 50-60 270KV / 2400W) is good also?

Not a big difference in price, but I got no idea how to make a good calculation ot the max speed related to the max power draw and max milage (if I would buy 1 or 2 decent battery for the system).

Or I should get an even higher Kv or lower Kv motor? There are so many on the market, I got no idea which would be the best to use...
PLS help me out to get the best!

Do a search on this forum for "Friction Drive" and spend some time reading the many threads.
It will help you understand which motors and controllers are best suited and also give you a lot of ideas on how best to put together a friction drive.

Well done ,Hillhater..i'd have never translated Fraction Motor = Friction Drive ? , assuming you are correct in your guess of course.

Here is a thread that has a variety of friction-drives featured. You may find some useful ideas there.

http://endless-sphere.com/forums/viewtopic.php?f=28&t=14403

I've read pretty nice amount of treads since I made my firs post.

But I still don't know which motor would be the best.
I would like to use it as adrian_sm uses it at his comutter booster.
As I read it he was using a 192 Kv motor (but larger diameter)

I would like to use a 270 or a 380 Kv motor, both rated at 2000 Watts (on 6s) or 2400 (8s)

What would be the differences if I use one or the other (with the same battery setup)?
I would need less power on the higher Kv model, or anything else (pros and cons please if anyone have experience with different KV's )

I would also like to set is as a constant contact, so it recharges the batteries in DH.
What electronics would I need (as a plus) compared to the 'simple' version?

THX in advance.

Hi,

Got your PM but will answer here. Hope you are cool with that.

My tips for selecting a friction drive motor (based on my style of friction drive, ie. direct drive on the wheel)
1) pick the biggest diameter that will fit
2) pick the longest motor

Why? The bigger the motor the more continuous torque it will be able to supply without over heating.

3) pick a low kv motor
Why? You want to select the motor diameter, battery voltage and motor KV to give a no load speed slightly above the cruise speed you would like to sustain. I typically gear it for 40-50kph. If your kv or battery voltage is too high the motor will not be running efficiently, and your controller will have a harder time limitting power. Leading to overheating. Plus generally it is better to go for a higher voltage and lower kv if you have the option. If you plan on using RC style ESC controllers I preferred using the cheaper 6s max controllers, and 170-200kv motor in the 59-63m diameter. If you can get an ebike controller to work, then if you can get or make a lower kv motor, then you could run 36v.

4) Power limitting
- to protect your motor, you need some way to limit the power. So if your controller can't do it (eg. RC ESC style controllers) then get a Cycle Analyst or something that can reduce the throttle if amps go to high.

As a rule of thumb I run 59/63mm motors upto 1000w reliably, but would not push the 50mm motors above 500w. In fact I don't bother with the 50mm motors any more, they only save a couple of hundred grams, but just don't have the surface area to shed the waste heat, so are much less reliable. Plus they haver smaller bearings.

5) Bearings
- I only use motors that have a skirt bearings. As these resolve the tire contact force in the bearings better.

As for the motors you linked to I would always pick the lowest kv first.

What is the better to choose?
http://hobbyking.com/hobbyking/store/__22036__NTM_Prop_Drive_50_60_270KV_2400W.html
http://hobbyking.com/hobbyking/store/__23521__NTM_Prop_Drive_50_60_Series_380KV_2665W.html
http://hobbyking.com/hobbyking/store/__22035__NTM_Prop_Drive_50_50_580KV_2000W.html

Click to expand...

But if you can fit the 59mm or 63mm motor, do it.
The SK3 series have been good.
http://hobbyking.com/hobbyking/store/__672__663__Electric_Motors-63mm.html

Hope that helps.


- Adrian

Do you want the type of friction drive that uses the motor-shell as the roller? Or, the type that uses a separate roller? that is the first vital question to narrowing down the selections.

I have a used Turnigy 63-74 (63mm diameter, 74mm long) RC motor with a Kv of 200 that I could sell you (I live in Kansas, central USA). the 149-Kv motors are what is best for a roller drive, but 200-Kv is useful.

spinningmagnets said:

Do you want the type of friction drive that uses the motor-shell as the roller? Or, the type that uses a separate roller? that is the first vital question to narrowing down the selections.

I have a used Turnigy 63-74 (63mm diameter, 74mm long) RC motor with a Kv of 200 that I could sell you (I live in Kansas, central USA). the 149-Kv motors are what is best for a roller drive, but 200-Kv is useful.

Click to expand...

THX for your offer, but I try to solve it with 50 mm motors, if I can (I live in Transylvania {Romania}, Europe).

Yes, I would like to use the shell as a roller.
The motors I've seen are about 35 USD and all in the range of 2000 W max.
My big question: What is more efficient to use? Low voltage and high current or the opposite.
I know it is way more expensive to get the high current (Battery, 'brains', controller cableing ect) but is we put the economic issue aside... which is better?
I know high amps make components HOT, but I ask it from the 'experience' way.... which 'feels' better?

Another one, if I should use the 'slowest' version, can I over volt it to get higher max speed (not always, only if I have to hurry)?
With a care (amp limiting) not to burn the stuff, of course!

Is there a way to make the electric setup 'dual' way: Like 5s for power saver (for crusing in city) and 8-10 s for fast(er) ride?
Would be nice to do it.
With normal batteries it is not too complicated, a swich and a few wires and it is easy to convert 2p (5s) into 10s, but I'm not shure if it is as easy with the Lipo batteries as well (not to mention I would need 2 controllers and so on)
Maybe there are advanced contollers as well, which can handle (with ease) the double voltage also.
This is just an idea... and I'm not in a hurry (the winter in my country is coooold, so I will make it only in the spring time)

I've read that the 63 mm wide motors are better. The posts was made a few years ago.
Is this still true, or the motors I would like to use would be good?

Does a lot changed since than, or still the 63 mm motors would be better?

I should use as low Kv motor as possible and use it as high voltage (with as low Ampers) as possibe to get the best result?

THX