New Electric Bicycle. MKIII

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Finally I found the time to write about my new electric bicycle!

This is my latest build and my best build so far.

As you can see from the photo, the bike has a small back wheel (20 inches), front suspensions, disk brakes and a central battery box that contains the battery (obviously), the controller and all the other connections (e-bike computer for example).

Here below I describe the process and all the modifications:

I started by buying a bicycle a few months back. I wanted something light and with front forks and disk brakes.

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I bought the above bike for 250$, used and in excellent condition.

In the meantime I also got an used motor, a 9C9807. Originally the motor was laced in a 26-inches rim and had the hall sensors burnt.

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I decided to use a sensorless controller, so I decided not to replace the hall sensors, but I replaced the original phase wires with 14AWG copper stranded wire as shown below.

Original wires (thin) vs new ones:

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I decided to use a cheap sensorless controller, KU123 from BMSbattery. I upgraded the controller with 100V capacitors and IRFB4110 high quality mosfets to support battery voltages up to 100v. I also “beefed-up” the main power traces on the controller board to improve current flow on the traces.

Original controller:

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High quality IRFB4110 mosfets:

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Controller modified with new capacitors and mosfets. Please note that the capacitor legs do not touch and they are quite apart, it’s just a camera angle “optical illusion”.

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Original board traces:

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Traces “beefed-up”:

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Then I got to work on the battery box. I wanted something better and larger than my previous bike, so I used a 11.5cm wide wooden board  and built it. Photos are pretty much self explanatory.

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Side covers:

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I attached the battery box to the frame using zip ties. It holds really well.

Lastly I decided to lace the motor into a 20 inches rim,spokes in a radial pattern, which turned out to be a pretty good choice. The bike has very good torque and can handle steep hills without overheating the motor.

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I also added an e-bike computer based on arduino to complete the job, so I have real time data on battery usage, speed, range left and so on:

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One thought on “New Electric Bicycle. MKIII

  1. I’m happy to see your last so nice upgrade….
    I think you should be pride of your creation, I certainly would be. I can’t imagine how much work had required, but the results are so good. As far as I can see, you have replaced almost every pieces with something original.
    Compliments one more time

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