Electric propulsion design process

Discussion in 'Electric Propulsion' started by Will Fraser, May 17, 2019.

  1. Will Fraser
    Joined: Feb 2014
    Posts: 146
    Likes: 10, Points: 18, Legacy Rep: 11
    Location: South Africa

    Will Fraser Senior Member

    I am in the process of creating a video series on the design process that I followed for my solar kayak. It will also include investigations into batteries, motor controllers etc. I hope the test demonstrations and discussions will be a useful design guide for other diy enthusiasts.

     
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  2. Will Fraser
    Joined: Feb 2014
    Posts: 146
    Likes: 10, Points: 18, Legacy Rep: 11
    Location: South Africa

    Will Fraser Senior Member

    To make testing easier, I am using the small toy motor and a 3W panel.
    The torque measurements need refinement but I am very pleased with how well the simple optical tachometer works.
    The results nevertheless clearly show the mismatch between the motor and panel. Best motor efficiency corresponds with an under-utilised panel and maximum panel power corresponds with an overloaded motor. In a follow-up video I will show how to calculate this motor-panel compatibility without the need for tests as well as options to remedy a mismatch.

     
  3. Dejay
    Joined: Mar 2018
    Posts: 315
    Likes: 42, Points: 28
    Location: Europe

    Dejay Senior Newbie

    Wow, amazing video! Finally got around to watching it :) I roughly understood the steps before but this lays it out very nicely. Thank you very much.

    Looking forward to your followup video on motor efficiency, that is the area where I understand the least so far.
     

  4. Will Fraser
    Joined: Feb 2014
    Posts: 146
    Likes: 10, Points: 18, Legacy Rep: 11
    Location: South Africa

    Will Fraser Senior Member

    The motor instalment.
    I did do a constant voltage test on the little 7V toy motor and got better results, including running torque at various loads.
    The efficiency is very low and as such the little motor does not lend itself to the simplified analysis described in the video.
    Fortunately, almost any motor powerful enough to be practical as a boat motor would be of high enough efficiency to use these simplified equations and ratios.

    I have since also built a bench-top "dyno" to test slightly larger motors, and there is a shiny new 2hp brushless motor waiting its turn. I am looking forward to doing some first-hand efficiency comparisons between brushed and brushless motors.

     
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