Another electric dirtbike...But with surprise!

rsnoiser

1 mW
Joined
Feb 3, 2017
Messages
16
Location
Oise (France)
Hello everyone, here is the presentation of my first try to convert a small ICE dirtbike to electric one.

I apology in advance for my bad english, I'll try to do my best for writing correctly.

This project started in 2017. I bought some parts:

- a Kelly controller (KBL48151X) with some accessories: throttle, contactor, harness, charge-meter
- a Turnigy Outrunner C80-100 motor (48V, 6500W, KV:180rpm/V)
- 2 Lithium batteries 6S 16Ah 10C from HobbyKing
- a small turnigy lithium charger

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The first step was to run the motor with the controller but the kelly's not a sensorless controller so I put some hall sensors inside the stator with a KTY temperature sensor.

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I also change all the bearings. You know, chinese quality...
It was good and I managed to test this motor about the torque with a scale.
At 50% of current motor, the scale give 1.2kg so I think a 20Nm torque was a good estimation for mecanic design.

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but I stopped it some weeks after to finish an old project who started in 2008:
a supermono motorbike racer with a Ducati motor (1098 for who knows) but with only one cylinder.
This was my biggest project so far. It took me 10 years to finish it but now the bike is racing in National championship but I think it's not the right place to speak about it!

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So, with this project closed, I resume my work about my electric little monster...
Next time, the frame...

To be continued...
 
Hello everyone, this time the frame.

At the begining, I wanted to put this motor inside a racing pocket bike.
But my wife's dad gave me this dirtbike frame:

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A Conti RX 650 Basic.

Even Google don't have an picture of this, so if someone have some informations, he's wellcome!

So, a bigger frame to work with and more space for all the parts.
I planned to do a belt stage reduction (12/60) to give more torque.
I did the output shaft with a KTM 50SX 10 teeth sprocket

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With CAD software, I designed a small housing for the output shaft to CNC mill it. But time is money, I did it with my 3D printer just to see if it was OK and also some part for the motor.

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At this moment, I was not sure how to put this outrunner inside the frame so I make a jig with my 3D printer, just to see the overall placement.

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3D printing is awesome for this kind of things, just CAD and print it to test, it's fast.
3D printed parts are OK for static but is it OK for real usable mecanic parts?

Ok, let's do it! I will make a complete housing for output shaft and motor, 60 teeth pulley and battery holder in 3D print, for the science!

Some time to design and many hours of printing:

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Next time, the controller and electric integration.

And yes, I made a plastic 12 teeth pulley just to see...(spoiler, pulley life time: 5mn!).

To be continued...
 
Hello everyone, this time electric integration and some parts.

I try many place but the kelly controller is big and the batteries are at the good place for me so where can I put this thing?
The kelly is big but not thick so left side was OK and the other side, I can put all the electric stuff: main contactor and fuse.
I made a plate in 3D print and it was perfect!

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Some wires, XT90 Y link and all is working.

For the settings, I've put the current motor and battery current at the minimum (20%) with a slope of 10s for the acceleration.
It's low but all is made in plastic, even the pulleys!

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My kids was using it with smile, not very fast (about 17 km/h) but a fun toy.
For me, I could hear the plastic screaming to stop!

LIke I said in last post, the 12 teeth motor pulley was dead in about 5mn.
Anyway, I made the same part in CNC milling but I made a mistake and the pulley was not very centered on the motor shaft (~0.8mm).

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It worked but the other pulley explosed with me on the bike in 1 meter on a little climb.

3D prints works but when you have some serious loads, it's another story...

I decided to make an adapter and 60 tooth aluminum pulley for the output shaft.
I changed the motot pulley for a 26 teeth that I cnc milled for the screws.

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A new plate was made to link together the motor shaft and the output shaft so the motor cannot move backward when loaded and also the belt tensioner.

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I set the current motor at 80%, battery current at 20% and slope rate at 1: it was a beast, battery current at the minimum!

The acceleration was very good for this small bike but too dangerous for my kids.
I play a lot with it but I made a mistake and the output shaft broke its plastic housing.

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What a dumb!! But anyway, 3D printing is here and I re-print it with some adjustments to make a better part, more robust.

I pushed the current motor to 90%, the battery current at 50% and it was explosive!
On every WOT (Wide Open Throttle) I've made, It did wheeling a lot. I record a 38 km/h speed on flat but with a massive acceleration for this small dirtbike.

I was not sure about the 3D printed part with a lot of loads but it works well. And for me, it's a real surprise to see this.
Obviously, I prefer to make part in "real" material (aluminium, steel) and do welds, use CNC mill and lathe but for a kid toy, 3D print is OK and can be a time saver for some tricky parts.

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Now, dirtbike is almost finished, I would like to make some fairing in fiber glass to cover dangerous parts, a better way to lock the batteries and find a way to select the limit of output power like some bike like a key switch or something else.
It will be great to set some parameters of the kelly controller without a PC.
Now, I must setting down the power and let the kids play with it!

I think it's time to do my own dirtbike and be ready to test it in real outdoor conditions.

To be continued...
 
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