Simple Ebike friction drive build?

[WelshGriff]

Hi guys

not sure if this is the correct part of the forum as most of the threads are of peoples actual builds, but I would really like to get into building a simple friction drive ebike to dip my toe in the ebike world water.

I have had a look into the basic but what i'm really looking for is a type of outrunner style similar to Keplars, I have a mini milling machine and lathe in my garage so I can build the housing ( this interests me the most)

The main question really is, is there a simple way to connect all this together? can I buy a battery, throttle and wiring and is essentially click together and go? There seems so much information out there it is mind boggling!

 

[dustNbone]

The wiring will be the easy part, there are lots of ways to go about it, all of which will work basically the same. The mechanics of a friction drive are by far more complicated than the wiring.

 

[WelshGriff]

Thanks dust, do you know of how I can just get a battery, throttle, and outrunner motor that can all work together?

Kepler advised this motor

https://hobbyking.com/en_us/kd-53-20-brushless-outrunner-195kv.html

And a 6s battery

Another thing I'm not sure about is the battery management, if I'm writing this correct? Does it control how the battery works? I just thought a throttle would regulate the power going to the motor?

All beginner questions I know!

 

[DanGT86]

Battery management systems manage the battery while charging and discharging. The throttle and controller do regulate the power going to the motor.

Think of it like this: The throttle and controller are requesting energy from the battery as per the settings of the controller. If they ask for too much then the battery management will interrupt the circuit to prevent overdrawing the batteries.

The simplest way to understand it is that a battery management system will monitor and protect individual cells. The RC motor controller (ESC) will monitor the bulk or sum voltage of all cells and cut power if the total voltage becomes too low. If your pack is well balanced then you can trust that the total voltage divided by the number of cells equals the individual cell voltages. As cells become unbalanced then the sum voltage of the whole pack becomes unreliable as an indicator of individual cell voltages. This same theory applies to bulk charging with a non balance charger. You can have one cell at 5v and another at 3v but the total will be 8v. This would look like 2 cells at 4v and you might think everything was fine. A BMS prevents this situation automatically.

A simple 6s battery will likely be an RC Lipo setup. In that case you can use an RC charger to manage and balance the batteries while charging and some cheap lipo alarms to keep you from overdrawing any of the cells. In this case you will be the management system meaning that you release the throttle when you hear the alarm. That is the simplest method for a beginner especially if you need to buy a charger anyway.


I hope that clears it up a little.

 

[WelshGriff]

Great post dan! That's for clearing a few things up for me! For trying to build a simple set up there doesn't seem to be much out there such as a bulk kit for battery controller throttle and a list of motors for example, I suppose that is the fun of it for some!

 

[spinningmagnets]

Start here:

Zibbys friction drive (this thread has become a friction drive index)
https://endless-sphere.com/forums/viewtopic.php?f=28&t=14403#p214997

 

[WelshGriff]

I've done a little reading (actually a lot), more unsure of everything now than before haha

How does this motor, ESC, and battery look for starters?

Turnigy AE100A Brushless ESC - https://hobbyking.com/en_us/turnigy-ae-100a-brushless-esc.html

Keda 56-63 195kV Brushless Outrunner 6S 1500W - https://hobbyking.com/en_us/kd-53-20-brushless-outrunner-195kv.html

Turnigy 4000mAh 6S Lipo pack - https://hobbyking.com/en_us/turnigy-4000mah-6s-30c-lipo-pack.html

 

[ScooterMan101]

What bike do you have to convert to electric ?

Do you have Hills or Mountains to go up ?

I ask because you are listing a motor that is suited to the Road , Light weight Road Bike .
Kepler has done allot of testing, and looks like he will have a whole kit available soon.

 

[WelshGriff]

Yeah it's an old simple road bike, nothing special really and I only plan on cruising the local bike paths, mostly flat with a little hills here and there.

This will be my first attempt at it so I don't want anything special really, (or too expensive) I'm more interested in the mechanics and machining the housing and stuff, this electrical side of things seems to be the biggest hurdle however!

Do you thing these components will work together? I'm also trying to find a throttle system, would a half twist handle bar system from eBay work? Or are there better out there?

 

[Chalo]

Here's a related but tangential question: Does it work to hook up an outrunner model airplane motor to a sensorless e-bike controller? I know that model ESCs don't like e-bike load profiles, but I don't know if there's any sort of deal breaker using a sensorless e-bike controller on an airplane motor that lacks Hall sensors.

 

[WelshGriff]

Sorry chalo, your question highlights my weakness on the whole ebike electrical field, I'm not sure I really understand what hall sensors are (I've seen them mentioned on here a few times but only by people who know what they are)!

 

[amberwolf]

It would probably work fine...as long as it's like Kepler's where the motor starts without a load on it, then the spin kicks it onto the tire and holds it there.

If it has to start while loaded it might not, from a stop.

As long as the motor is unloaded and/or is already spinning in the right direction, the sensorless ebike controller can work.

Another caveat is that if the motor is very high RPM, the "eRPM" may be too high for most ebike controllers, sensorless or not. Probably not the case for a friction drive, but has been a problem on some other high speed-with-large-reductions drives.



As for what hall sensors are and how they work, there is info on that and other things you'll probably want to know in the Motor Technology subforum Sticky Index thread, and the "how motors work" thread.

 

[WelshGriff]

Cheers amber, I'll check out that info!

Yes it will start without a load, then kick onto the tyre! I've seen a few designs so I'll use the bits I think would work on my bike and design it to fit

 

[WelshGriff]

Can anyone explain what a BEC is? I've emailed hobby kind for a list of parts and he advised this

https://hobbyking.com/en_us/hobbyking-yep-20a-hv-2-12s-sbec-w-selectable-voltage-output.html

But I'm not sure what is does or where it is supposed to go?

 

[amberwolf]

I dunno what it stands for, but there's a lot of builds that use or mention one; I'm sure someone explains it well enough to infer everything else:
https://endless-sphere.com/forums/search.php?keywords=BEC&terms=all&author=&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search