First testrun of the E-Puch

Today I’ve made the first test-run of the E-Puch. As I’ve written about before it is an old ICE moped that I’ve removed the engine and replaced with an electric BLDC outrunner.

Today, me and my brother threw everything together for a quick testrun just to see that everything works, and try out the performance.

E-Puch ready for testrun
E-Puch ready for testrun

I will soon write a post about the motor controller which I ordered from a guy named Lyen on the Endless Sphere forum. It is currently set to limit battery current around 40 A, but I think I could increase the current limit by 50% without any modifications. Which would give 50% more torque.

Controller temporarily mounted to the frame
Controller temporarily mounted to the frame

The motor is mounted on two 5 mm aluminum sheets that are bolted in the original motor holes in the frame.

Motor and motor mount
Motor and motor mount, I think I'll remove the axle on this side.

Except for the motor and motor sprocket the drivetrain is original.

Original chain with 10 tooth front sprocket and 43 tooth rear sprocket
Original chain with 10 tooth front sprocket and 43 tooth rear sprocket

I use 4 bricks of 6S 5 Ah Turnigy 20C batteries mounted in 12S2P configuration. For now these are in a plastic box on the rear end of the moped.

Temporary battery box
Temporary battery box

And at last a video of my father trying the moped.

6 thoughts on “First testrun of the E-Puch”

  1. Hey cool toy! I’m looking to do the same exact thing, help me out? Man that thing flies to. So what are specs like amp draw , battery mah? How many miles per charge? I’m ready to build one and would live some advice


    1. Thanks!

      I’m not sure about the amp draw while riding, or the Wh/km figures. I just got this to work for a couple of days before I managed to fry the motor. The controller limits the battery current to 65 A and the phase current to 160 A but for a second or two on startup the current is unlimited. With the batteries fully charged at 50 V, 65 A will result in a continous power around 3 kW. I’ve been told that this should result in around 8 kW at startup which is what fried the motor. We did several hard accelerations during a short period of time, for normal use the motor was barely warm.

      While testing the moped I used 4 bricks of 22.2 V 5 Ah batteries 450 Wh, this is not enough for any practical use, my E-bike use around 12 Wh/km with some pedaling and I would estimate that the moped use around 25 Wh/km since it’s both heavier, faster and do not allow any pedaling. 15 km range with some battery margin is not enough I would say.

      I would be happy to give you advice or have general discussions with you if you want to build something similar, either as comments here or by e-mail.

  2. Hey

    great project! im doing starting a similar project for my final in school, which will hopefully get me into engineering school afterwards, since i never had anything to do with RC cars, i spend a couple days reading up on how to make a controller.
    I would appreciate if you could give me some details about it, or even the price you paid from Lyen.

    keep up to good work!


    1. Making a controller is definitely doable but would require a lot of work. for a first project I would recommend that you buy one instead.

      I used this one: but with other MOSFETs. If you look at the “Items for sale – New” ( at endless sphere you can find both larger and smaller controllers from him. The are all based on the infineon controller chip that can be programmed from a computer if you would like to change the power output.

      Just ask if you have any more questions.


      1. I just bought the lyen controller and waiting for it to arrive, however i told him to program it for 10s 37V and i hope thats good enough, the reason why is because the engine we got only supports max 10s 37v so im planning on running 10s2p.
        i just was wondering how you do it when youre rolling? I dont really know how the technical term is but when you are idling down a hill, how do you make the engine stop turning or do you just let the motor rotate? because in the pictures i just see that the chain is directly on the motor/back wheel.


        ps. happy new year from switzerland.

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