Results 1 to 4 of 4

Thread: Control unit for electric cycle

  1. #1
    Gold Member Martinco's Avatar
    Join Date
    Oct 2008
    Location
    Rustenburg
    Posts
    927
    Thanks
    175
    Thanked 136 Times in 108 Posts

    Control unit for electric cycle

    Hi Guys,

    Can somebody please help me ?

    I am busy fixing an electric motor cycle. ( one of these small jobs that fold up and fits into the boot of a car. )
    This belongs to a friend of mine that stays in Toti and has recently been diagnosed with cancer. He wants to lug this thing along in his motor home and then to enable him to drive to the cafe or shop in the park.
    Ok, to get back to the problem.......... It seems as though the control unit box that regulates the current to the drive motor has been fried. This unit controls other things like the flashers. hooter and light as well. All these functions work 100%. Just the motor part stopped working.
    So I was thinking that if I fit a completely separate control box for the motor, that should solve the problem.
    Here are the specs: 36 volt battery system with a 36 volt motor and peak current at 18 amp. Also shows 500 watt on the motor.
    However what I have not seen before is the twist grip potentiometer. It has 3 wires running into the unit but does not use the conventional carbon slide and brass/copper trace like that of an older type radio.
    This unit has a magnet connected to the twist grip and only moves between two metal stops very close to the back plate which I assume has some sort of coil or other gizimo imbedded in the bakelite back plate.
    If need be and with a lot of effort I can change this to a conventional potentiometer but obviously would like to get the existing twist grip working.
    Now.......can anybody help me with a circuit diagram that can a) use the existing pot or b) a diagram that can use a standard pot with an indication of the components and values needed.?
    Martin Coetzee
    Supplier of Stainless Steel Band and Buckle and various fastening systems. Steel, Plastic, Galvanized, PET and Poly woven.
    We solve your fastening problems.
    www.straptite.com

    You may never know what results will come from your actions, but if you do nothing, there will be no results... Rudy Malan 05/03/2011

  2. #2
    Diamond Member Justloadit's Avatar
    Join Date
    Nov 2010
    Location
    Johannesburg
    Posts
    2,671
    Thanks
    88
    Thanked 544 Times in 460 Posts
    Blog Entries
    1
    Hi Martin,

    the device in the hand grip is a hall effect device, which changes an output voltage according to the gaus of the magnet. It runs off 5V, and has a range of 0 to 5V for a north to south transition. In your case there is only a north or a south transition, so the voltage will vary from 2.5 to zero or 2.5V to 5V. In the past, what I have found with the units is that the unit has fried, because the bad quality motor cause it to fail due to the demagnetization of the motor rotor.

    Before doing anything on this unit, check out the motor first.connect them o tor directly to the battery with no load, and the current should be a couple of hundred milli amps. If the magnetics has decreased, you will note that the current is a couple of amps. The problem is to find a replacement motor. In the case that the motor is fine then, a simple PWM circuit using a FET will do the job. A typical chip could be a SG3525. All components available from Mantech, who have a branch in Durban
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar and LED lighting solutions - www.microsolve.co.za

  3. Thanks given for this post:

    Martinco (14-Feb-11)

  4. #3
    Gold Member Martinco's Avatar
    Join Date
    Oct 2008
    Location
    Rustenburg
    Posts
    927
    Thanks
    175
    Thanked 136 Times in 108 Posts
    Thanks !!!!

    I have checked the motor.........seems fine. Is there a way I can check the hall effect device with a meter ? In the meantime I am going to open the present controller box and replace all the ICs and see what happens but if the trouble is in the grip then this will not help, however, thinking about it, the trouble must be in the control box because the motor runs flatout without the hall sensor being connected. Or have I lost it ?
    Martin Coetzee
    Supplier of Stainless Steel Band and Buckle and various fastening systems. Steel, Plastic, Galvanized, PET and Poly woven.
    We solve your fastening problems.
    www.straptite.com

    You may never know what results will come from your actions, but if you do nothing, there will be no results... Rudy Malan 05/03/2011

  5. #4
    Diamond Member Justloadit's Avatar
    Join Date
    Nov 2010
    Location
    Johannesburg
    Posts
    2,671
    Thanks
    88
    Thanked 544 Times in 460 Posts
    Blog Entries
    1
    Very simple to test the hand grip hall effect device. Check the PCB connection, and look for the power connections. One must be ground, one must be 5V, and the third will be the control voltage. Using a multimeter, simply measure the control signal, while twisting the grip backwards and forwards. The voltage should change in sync with the twist. In my experience, it is very rare these devices fail. Usually the FET fails, not due to over current, but rather temperature, and the junction becomes a short circuit. In all probability, the FET is damaged, and requires replacement. Use the www.mantech.co.za web site to do your component search, it is a comprehensive site.
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar and LED lighting solutions - www.microsolve.co.za

  6. Thanks given for this post:

    Martinco (15-Feb-11)

Similar Threads

  1. 14 year old killed during a cycle race
    By murdock in forum General Chat Forum
    Replies: 7
    Last Post: 09-Feb-11, 07:12 PM
  2. Document Development Life Cycle - DDLC
    By Cream in forum Technology Forum
    Replies: 0
    Last Post: 28-Sep-10, 06:32 PM
  3. [Article] Portable electric lights
    By Master Electrician in forum Electrical Contracting Industry Forum
    Replies: 1
    Last Post: 17-Sep-10, 09:54 PM
  4. Electric fences
    By mikilianis in forum Electrical Contracting Industry Forum
    Replies: 2
    Last Post: 10-Mar-09, 02:18 PM
  5. Registration of unit standards and qualifications.
    By Dave A in forum Pest Control Industry Forum
    Replies: 5
    Last Post: 16-Jul-08, 04:12 PM

Did you like this article? Share it with your favourite social network.

Did you like this article? Share it with your favourite social network.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •