12v fan and 7v solar???

Discussion in 'General Electronics Chat' started by Terminaloverload, Mar 15, 2014.

  1. Terminaloverload

    Thread Starter New Member

    Mar 15, 2014
    1
    0
    New here and know little so just need a simple answer.
    I have a Gelid 12 silent pc fan rated at 12v 0.08a.
    I have a mini solar panel rated at 7v 0.14a.
    The fan has a molex connector with red, yellow and black wire. I believe the black is earth, red 12v and yellow 5v (May be incorrect?).

    Will the solar panel run the fan reliably and safely if connected directly. It only needs to run optimally in strong sunlight.

    Thanks in advance.

    Please move thread if in wrong place etc.
     
  2. spinnaker

    AAC Fanatic!

    Oct 29, 2009
    4,887
    1,014
    The fan will run at half speed. Get two panels and wire them in series.
     
  3. spinnaker

    AAC Fanatic!

    Oct 29, 2009
    4,887
    1,014
    Red and black power the fan. Yellow is sense and you won't need it.
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,392
    1,605
    Motors and solar cells make a particularly poor combination.

    When a motor starts it usually needs an extra jolt of current. Solar cells simply cannot give this jolt; when you draw a lot of current their voltage falls back to near zero as they put out their max of current.

    What is worse is the devices sitting there as the sun comes up: the motor is stalled as the sun increases, the current builds up but the voltage remains low so all that happens is the motor gets a little warm.

    I've seen solar powered fans on hats so there is some combination that works... but you can always spin the hat to start it.

    It's not dangerous so try it and see. Experiment some but don't be disappointed if it doesn't work. (Be happy if it does.)
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,173
    397
    ErnieM is right, but the problem can be overcome by adding a Mini-Maximiser or Solar Gleaner which just adds a capacitor across solar panel,SP, & electronically switches the load across the cap when charged to desired value. If SP outpui is sufficient to run load, no further action is required, but if SP V falls, the switching repeats.
     
  6. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,173
    397
    Should work fine with what you have; tried 12 V, 90 mA " Superred" fan with 4.2 V OC, 80 mA SC solar cell. Self starts with about 2/3 full sun. With 1000 uF, can start & run with about 1/3 full sun - but will not blow out a candle.
     
Loading...