Electric Gokart for thesis

[mckutzy]

Why no pics, Are you not aloud to take pics in your school?

 

[Flurky123]

Why no pics, Are you not aloud to take pics in your school?

There will be pics. But nothing about the chassis, the gokart I use is an old gokart for kids. I'll throw off the the pedals, then I'll put the motor on

Flurky123

 

[Flurky123]

This week I'd like to build the plans. I'll show them here at first, but I will need some help. If I'm right I have to attach the motor to the controller, attach a potentiometer (throttle), then attach the motor each taking up 2 pins.

Then I'd still have to use something to brake, maybe just cut of tension and current at all. I won't use the regenerative brake, it'll save some forces to the shaft and I don't think the benefits will be great. I'll probably use a hydraulic system. That same pedal should asswell cut off power in one way. In between components I might have to use some circuit breakers.

I don't think it'll be the most sophisticated circuit, but I'll have to think about all components. Otherwise I might warm up things a bit too hot

Flurky123

 

[itsid]

This week I'd like to build the plans. I'll show them here at first, but I will need some help. If I'm right I have to attach the motor to the controller, attach a potentiometer (throttle), then attach the motor each taking up 2 pins.

Then I'd still have to use something to brake, maybe just cut of tension and current at all. I won't use the regenerative brake, it'll save some forces to the shaft and I don't think the benefits will be great. I'll probably use a hydraulic system. That same pedal should asswell cut off power in one way. In between components I might have to use some circuit breakers.

I don't think it'll be the most sophisticated circuit, but I'll have to think about all components. Otherwise I might warm up things a bit too hot

Flurky123

Almost..

first:
please DO NOT refer to the throttle as a potentiometer until you are sure it IS a potentiometer!
(It most likely isn't a potentiometer but a hall effect sensor)
But I haven't checked.

it can be connected with 2, 3 or even 5 wires, search the parts you intend to use and check the diagrams;
do not just assume things if it's getting serious.

Do some research, this is YOUR thesis, not ours; you need to stand up against questioning, so you better know your stuff.

Batteries in series up to your needed voltage, and the sequenz of serial batteries in parallel for more charge (Ah) for a bigger range;
keep in mind that this increases weight..

Then One cable to the controller, the other one to a FUSE, then to the controller.
You won't connect a battery array 1:1 to a controller, especially not if we talk about serious currents; better blow a fuse than your candle, right

The controller is also connected to the motor,
sometimes directly, sometimes NOT (depends on wattage, controller and if you want to use back E.M.F. or not)
there might be contactors, H-bridges etc. to take into consideration.

And the controller also is connected to the throttle,
wich can be either a hall effect sensor or a potentiometer or anything else that can provide the correct signal for the controller.
Check that with your controller manual!

Most throttles are 5V so it's safe to just add a tiny switch to the brake pedal that cuts the throttle if the brake pedal is pushed.

regenerative braking isn't to much hassle most of the times, and it's an "eco friendly" improvement you can set up...
I don't know but I think it's a good idea
(saving a little energy is better than wasting all of it )
Anyways, you will need some electronics to make it work, no big deal but a good amount of research again.

Last but not least, you will need a good braking system, mechanical is okay, hydraulic is better, you must get the kart to stop at any time within "no time"!
Try to find an old motorbike and salvage the brake but make sure it's working.

Sooo.

Here's what to do:
first: find the controller you will be using on the internet, get as many information you can, BEST: find the wiring diagram!
(manual of the original device for example)
second: check all the original parts for prices and availability, note down original part numbers etc. again find all the info you can. (what type of throttle, how many wires, which ones on the controller.. everything!)
and finally: find the parts you want to include (pedal throttle instead of grip for example) check that they're compatible, make sure youhave a source, and the datasheets in case you need them first.
And get some more switches (a killswitch is always a good idea)
maybe a keyed switch to prevent others from using the kart in the first place, things like that.

Okay, good luck, let us know if you get stuck somewhere;
we're here to help; but you need to do the work

'sid

 

[Flurky123]

I've been searching around for some information. I'll be using the my1020 36V/1000W motor. It's a brush motor, so I have to use a controller for this kind of motor. I was looking around and I found this controller. I can't really find a lot of information. The site provides some specifications although I don't need the brake lights and things like that. I think it'll do but I'm not quite sure though. If these 2 components are compatible, I can go and search for switches, sources, circuit-breakers and wiring. I still have to find a way to deal with the current-peaks, or won't this be a problem?

Hope to get the plans ready after exams
Hope you can help me out.

Flurky123

 

[itsid]

Look closely at the watermark of the image of the controller.. see it?

Go and ask for a specsheet or documents of said controller (CT09)
at
http://chinatmax.com/message.html
(the url in the watermark and maker of the controller)


'sid

 

[Flurky123]

I've send a mail, since the site given is Chinese . I hope to get a response quickly, although I doubt it.

But what do you think. It seems like a decent controller to me. I don't think it will cause any problems if I would leave the pins for the braking lights open (since it is on most controllers).

There's just one thing bothering me: it's suitable for 30A. Since the motor is 1000W/36V, this comes with 27.77A. Within this simple calculation I didn't count on the efficiency of the motor, and peak currents. This might leave the controller broken, maybe the answer is in the datasheets, I don't really know.

This is the hardest part I came to right now. At first I didn't know what a controller was. Now I have to decide which one to use. But I will get there eventually

Flurky123

 

[itsid]

It is a cheap chinese controller, and I would expect anything fancy;
but I've seen this controller on many different scooters and they all do fine.
It's simple, most likely not the best quality, but it will do for the my1020 motor
(that's exactly the motor in the scooters.. that's why I recommended it in the first place)
and it's cheap

You can leave the brake light slot empty, but it'll be a perfect spot if you -one day- want to trigger a regenerative braking system, that's where you want to trigger the relais.

I think the controller is rated at 30A with a hidden peak of maybe 45Amps or something to make sure you will neither burn the controller nor the motor.
And you can always use the so called turbo trigger to reduce the current to 23 Amps (800W)

the my1020 is made by unite motors (http://www.unitemotor.com/) there you'll find the spec sheet for most my1020s,
I think the controller is a clone of their bcx36 series (but I don't know for sure)

You cannot break the controller with a 'bigger' motor, you will simply underpower the motor, not overpower the controller

Oh, and acording to the little info there is on the site, it's a hall effect throttle.
So until you have the documents, you have time to find a hall throttle pedal (or grip if you prefere)
0-5V is most likely the one you want.
should be below 20 USD; I've seen one that's over 100.. but that's just plain stupid.

'sid

 

[Flurky123]

I've had a conversation with a teacher today, and searched around for some information. I'm getting to the point right now. Really going where I want to go

At first: I'll use the my1020 36V/1kW. It's a motor I can find a lot on the internet. It seems to be decent, since it has been used on other electric gokarts. Asswell I can find a nice amount of specifications on this motor. I'll take the 36V version since this takes up one less 12V battery and I don't want to use a converter or anything. This might take up the current, but I think I can deal with it. I'll buy it from tncscooters.

Secondly: I've been looking around for a nice controller. According to the fact it's quite hard to find a decent controller with a good amount of specs, I had to spend a lot of time on this one. I found someone's blog and he did app. the same project and used the CT-660B9. I looked it up and saw a (cheap) controller with wiring details, etc. I'll buy this controller from tncscooters asswell.

At last: I have to find some more components.

I'm taking care off the batteries right now. I'll supply the motor with 3 batteries (12V/+-30Ah) in serial. This will increase weight, but I'll use the weight in a good way (since I have to get some weight up front to cancel out the gokart falling over) .

I'll try to find other components like the hall effect throttle, circuit-breakers and switches from tncscooters asswell to combine them into 1 shipping.

For now, I think I can go on my own (for a while). I'll have to thank you a lot, you really helped me a lot further in my project. My aim is to make anything fit in februari, I hope not to get any unsuspected problems (although I have one already: there's limited space between the axis and the chassis, not enought to get a 60 tooth sprocket inbetween) I'll probably increase the height of the chassis in one way.

I'll keep in touch by regularly posting photos/ videos.

Flurky123

 

[Flurky123]

Hey again

Since I finished the exams I'm have some time to work on my project again. I have still got a bit work to do, but I need to find some batteries first. I already have a bit of information about these batteries. I Know I have to use tractionbatteries (3x12V serial). This certainly isn't cheap and I'd like to ask if you know a nice place to buy these things. I've been looking around and all I can find is about €75 for one battery (+-40Ah).

Do you know any places where this could be cheaper?

Thanks in advance
Flurky123

 

[Flurky123]

Hello,

It's been a while since you all heard of me. But I'm back. I did some buying and waiting and finally I can start.

So I ordered the MY1020 36V/1000W motor. In combination with 3 cyclic batteries of 18Ah and the CT660B9 controller, I want to control speed.

Today I just connected the electrical part of my thesis and let the motor run on free mode.

This is the result: (Talking in the video is in Dutch)
Video

I hope to do all the mechanical work in the next 2 weeks. Take in mind that I'll use an old children-gokart.

Flurky123

 

[itsid]

nice torque, isn't it

We have another belgian user wanting to build an electric gokart with a my1020...
Fenrir
Maybe you can share some experience with him

You both have asimilar weight to carry, so I like to add another advice
-or better- word of caution.
I know the my1020 come with a #25 sprocket,
And I totally would try that if you already have the parts.
But be prepared to switch to a #35 chain,
I think a bigger jolt can just break the smaller chain,
and even more with a 1kW motor than with the 500W Fenrir ordered.
So when you buy the axle sprocket and it's cheap enough, get a #35 as well, to save the shipping fees


'sid

 

[Flurky123]

Hello,

Well, I actually ordered the sprocket already. I used tncscooters to order all parts except for the motor and batteries. So the sprocket is already here.

There is some nice ammount of torque on that motor, you can especially see that if I let go off the brake and go full throttle . So my plans are to push the the throttle nice and easy to start. After I'm ready with my project I might play around with the gokart

And about that person you told me about: I will contact him

Flurky123

 

[Flurky123]

Hello again,

This afternoon I stripped my gokart from the pedals. I wanted to post a video about what it looks like, but remember it's an old pre-built gokart for children. It's rather small and definitely not strong enough.

My plans were to put the motor in the back (although there is limited space to put it), put the batteries up front (to divide weight), and to attach the controller somewhere close to the pedals.

What I was planning to to is to attach the sprocket (T8F) to a kind of plate with the correct diameters, so I can attach one to the other, and weld it together. My other idea was to make a regular (mechanical friction) brake to the other side of that cylindric plate.

I still dont know off a good system to attach the motor to the back. I have to be able to make something reasonably strong, where I can change the position of the motor (in a limited amount) just to put tension on the chain. Any ideas?

Video

Don't mind the little spocket that's already attached, it was welded already and I can't see a reason to remove it.

 

[Flurky123]

Hello,

I've got a question.

Could someone explain me how the hall effect throttle exactly works? I know you have got 2 wires for the tension, and an output signal. Can someone tell me how the output signal is adjusted, what kind of signal it is (DC, pulse DC, PWM,...) and how the controller would adjust the bigger voltage (Opamp, duty cycle, ...)

All I know for the moment is that the signal sent to the motor is PWM.

Thanks in advance
Flurky123

 

[itsid]

It's basically a magnetic field sensor.

The closer "a magnet" comes close to the sensor, the less restrictive the module is to the applied voltage.

Most throttle lines are 0-5V, that is the controller applies 5V and expects anything from 0V up to 5V on the signal line. (I think pure DC.. no pulse)

A throttle can be close to anything in between, some go down to no less than 0.9V, others only up to 4.3V or something,
depends on the actual sensor and the relative position of the magnet.

Most programmable controllers are self adjusting to those values, so you always have a 0-100% range.

How the controller adjusts the motor power according to throttle position depends on the controller;
Most likely it's a single microprocessor that does the pulse wave conversion.
4V in -> 80% of the time full power applied...

'sid

 

[Flurky123]

Hello,

So far I get it

I just don't really understand how the magnetic force changes the electrical voltage output. Does this have anything to do with the force of the magnet of does the sensor just measure the magnetic force at that time?

Flurky123

 

[itsid]

Well..
if I understand your question correctly both

every electric conductive material 'senses' it's surrounding magnetic field.
(hence electromagnetic force. )
Due to the Lorentz-force, more electrons are attracted to one side of the material.
A Hall effect sensor now makes use of the indifference between it's two sides
which act like some sort of capacitor.
Say your current flows north south in the conductive material,
said difference is measured east west.
the bigger the indifference, the bigger the voltage.
(really, think of it as a capacitor here )

And the indifference is based on the voltage, the current and the magnetic force.
Or more precise the densitiy of the magnetic field. (I don't know the correct english term for "magnetische Flussdichte")

So if you use a bigger or stronger magnet, it can be further away from the sensor to produce the same amount of output.
If you use a weaker magnet, it needs to be closer.

'sid

 

[Flurky123]

Allright, I think I get it now.

Thanks a lot!
Flurky123

 

[Flurky123]

Hello everyone

You haven't heard me in a while, but I'm back. I took some pictures of the project until now. Still waiting to receive 2 sprockets and a chain. I ordered a sprocket (T8F) from tncscooters.com but it's, for some reason, not compatible with an 8mm chain. Now I can get a motor sprocket 9 teeth, a axle sprocket 52 teeth and a chain (8mm) for about €25. Hope it'll go soon. I need to get it finished till friday 20th of june

In the pics you'll see the motor holder, the motor, the battery pack, the controller and some welding to get the frame higher. I hope you appreciate me coming back