Solar cpu fan help

Discussion in 'The Projects Forum' started by MarkS, Jan 28, 2014.

  1. MarkS

    Thread Starter New Member

    Jan 28, 2014
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    I am building a solar collector out of drink cans, and have a 12v 1.6A fan that I would like to run for ventilation. When I hook it up to a car battery, it runs fine. When I hook it up to a 12v 1.5 watt battery charger, it does nothing.

    What size (watt?) solar panel do I need to run the fan? Should I get a different fan that requires less power? I see these on you tube all the time and they all seem to run on really small solar cells? Help!
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Measure the actual voltage when using the charger, some need to see a battery connected.
    Max.
     
  3. wayneh

    Expert

    Sep 9, 2010
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    So you expect a 19W fan to run off a 1.5W supply, and you're surprised it doesn't work? C'mon.
     
    MarkS likes this.
  4. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    That better by an awfully large and / or efficient collector to compensate for the energy lose from a 1.6A fan.

    or you are adding an additional solar panel to run the fan?

    Just do your math: P=I*E

    That is assuming you will get a panel that is really at it's power rating and you have it under ideal conditions. You might want to up size a bit.
     
  5. MarkS

    Thread Starter New Member

    Jan 28, 2014
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    I didn't know it was a 19 watt fan! So, what would be a good combination for a small solar panel and a small fan? The CPU fan was given to me; I didn't realize it was 19 watts...I don't know much about electricity. As far as the 12v 1.5 watt panel that I have, what size fan could it run? Again, I only want it to run when the sun is out and don't mind if it runs at half speeds when partly sunny. Thanks again for your advice.
     
  6. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    I would start with air flow required. With battery operated fan, was there any excess air flow? If 19 W fan is needed, I would aim for a 30 W panel, & if necessary add a soft start ckt. I gather that the main purpose is to collect heat and distribute it with a fan.
     
  7. wayneh

    Expert

    Sep 9, 2010
    12,126
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    Well then here's an important fact: The power consumed by a component is the product of the voltage across it and the current flowing thru it, volts x amps, as spinnaker noted earlier (E=voltage in his post). Using Ohms law, you can also show that it is I^2•R.

    Pay attention to the comments on air flow. Moving air requires work, so the work done by the fan is determined by how much air you need to move. Many computer fans are 12V and use MUCH less current than 1.6A. Many are 0.1-0.3A and might be fine for your application.
     
  8. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    P = I * E every time. :)
     
  9. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    P = (12 volts)(1.6 amperes) = 19.2 watts
     
  10. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Or if you do not need much air, I have a 12 V, DC, .06 A fan available. Runs well on 1/2 of a 2 W solar panel.
     
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