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Solar cell power

Discussion in 'General Electronics Discussion' started by colum, Mar 7, 2021.

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  1. colum

    colum

    155
    4
    Jul 25, 2013
    I have 2 x 7v Solar cells in driving a small 6v DC motor at 7v it will not start until I push the shaft and then it runs with good speed and powers a music box easily
    Without using a relay capacitor booster is there anyway a capacitor would work on a 2 wire DC motor or is there another way...Thanks..colum
     
  2. bertus

    bertus Moderator

    2,051
    773
    Nov 8, 2019
    Hello,

    It sounds as if the solar cells can not manage the inrush current of the motor.
    The inrush current can be much higher as the running current.
    From the wiki:
    Motors
    When an electric motor, AC or DC, is first energized, the rotor is not moving, and a current equivalent to the stalled current will flow, reducing as the motor picks up speed and develops a back EMF to oppose the supply. AC induction motors behave as transformers with a shorted secondary until the rotor begins to move, while brushed motors present essentially the winding resistance. The duration of the starting transient is less if the mechanical load on the motor is relieved until it has picked up speed.

    For high-power motors, the winding configuration may be changed (wye at start and then delta) during start-up to reduce the current drawn.

    https://en.wikipedia.org/wiki/Inrush_current

    bertus
     
  3. Audioguru

    Audioguru

    3,393
    733
    Sep 24, 2016
    Are your soar cells connected in series (wrong) or in parallel (correct)?
    Are the solar cells in bright sunlight (correct) or in the shade (wrong)?
     
  4. colum

    colum

    155
    4
    Jul 25, 2013
     
  5. colum

    colum

    155
    4
    Jul 25, 2013
    Thanks bertus its back to the drawing board...colum
     
  6. Bluejets

    Bluejets

    5,025
    1,048
    Oct 5, 2014
    An option here might be to run the motor from say 4 or 5 NiMh rechargable cells in series and then use the panels in series to charge the battery.
    Some form of regulator or isolating diode may be necessary betweem the panel and battery.
     
  7. colum

    colum

    155
    4
    Jul 25, 2013
    Thanks Bluejets Thats probably my best option and one I would never have thought of...colum
     
  8. colum

    colum

    155
    4
    Jul 25, 2013
    The battery system will not work, the voltage applied to the motor goes to zero on startup
    I think it will need a timer and relay to give the rechargable battery time to powerup...colum
     
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