# Building Electric Scooter - Need Help with Motor

#### wteele

Joined Feb 8, 2019
6
Hey guys, I'm building an electric scooter and have all the parts necessary to make the motor work. Everything is wired up, and the motor should be running, but it's not. Am I making any mistakes?

As a motor, I am using a VW generator. Supposedly, this motor can handle 12V in the field coils (stator) with 8 amps capacity, and 48v on the armature (rotor) with much higher amps capacity. Below is the link to the file that has a picture of the motor and the wirings (explained below).

Below are the components I'm using:

Battery pack - 78 x LG HG2 18650 batteries and the respective BMS with 20A continous current, for a 48v, 20A battery.
DC to DC converter - takes in the 48V directly from the Battery BMS, and converts it into 12V with 10A max current. I'm using this to power the field coils (stator) in the motor.
Motor speed controller (1000W) - connects to the Battery BMS (in parallel to the DC to DC converter) and outputs the power directly to the armature (rotor) in the motor. The power is regulated via a throttle connected to the speed controller as well.
VW Generator as motor - this motor is supposed to work as a typical shunt motor.

Below is my super basic wiring (forgive my lack of diagram knowledge). Hope it helps.

Desired diagram (full power on both parts of the motor, slide 2) - This does not work, and is where I need your precious help

Test diagram (just 12V with both parts on closed circuit, slide 3) - This does work, check the closed circuit connection (red line)

THANK YOU VERY MUCH!

Joined Feb 20, 2016
3,190
Just upload the JPG imges directly to here.
Is the VW "generator" actually an alternator? If so, it will not run as a motor without a controller similar to a BLDC .

Have you tried the "motor" straight on a battery?

#### wteele

Joined Feb 8, 2019
6
Just upload the JPG imges directly to here.
Is the VW "generator" actually an alternator? If so, it will not run as a motor without a controller similar to a BLDC .

Have you tried the "motor" straight on a battery?
Sorry for that! You're right! You can try the links again, they should work. I set public access.

Regarding your question, I don't want to run the full power to the motor because the field coils might fry... Should I anyways?

Joined Feb 20, 2016
3,190
A lot will depend on the circuit of your speed controller.
I don't think you can run it as you require if the speed controller is sinking current. You may have to get to both ends of the windings, not have them commoned to chassis.

Like this.

Last edited:

#### wteele

Joined Feb 8, 2019
6
A lot will depend on the circuit of your speed controller.
I don't think you can run it as you require if the speed controller is sinking current. You may have to get to both ends of the windings, not have them commoned to chassis.
View attachment 169802
Like this.
Dendad, thanks for your response. Could you mind sending me the picture to my email <snip>, the resolution here makes it impossible to see. Appreciate your time.

Joined Feb 20, 2016
3,190

#### wteele

Joined Feb 8, 2019
6
Awesome, I'll give it a try.

I did run it direct from the speed controller (as you suggested earlier) and wired it as a closed circuit (stator + rotor) and runs beautifully. The throttle works flawlessly and the torque and rpm are great. Problem is, it does heat up a bit. Maybe the field coils have a lot of resistance and waste heat as power.

Any thoughts?

Joined Feb 20, 2016
3,190
You could try backing off the field current. It mat not need the full 12V on the field windings.

#### wteele

Joined Feb 8, 2019
6
You could try backing off the field current. It mat not need the full 12V on the field windings.

Roger that! Thank you.

#### djsfantasi

Joined Apr 11, 2010
5,853
Dendad, thanks for your response. Could you mind sending me the picture to my email <snip>, the resolution here makes it impossible to see. Appreciate your time.
Wicked bad idea! Never, never, ever post your email address. I expect a moderator to come along and remove it. I’m not being an a$$, it’s for your own protection! Peace Thread Starter #### wteele Joined Feb 8, 2019 6 Wicked bad idea! Never, never, ever post your email address. I expect a moderator to come along and remove it. I’m not being an a$$, it’s for your own protection! Peace
Crap, guess you're right. Hope they remove it.

#### djsfantasi

Joined Apr 11, 2010
5,853
Crap, guess you're right. Hope they remove it.
You can remove it yourself. There is an Edit button beneath any of your posts. Click it and change the post.