12v dc axial fan problem

Discussion in 'The Projects Forum' started by jkozacki, Mar 26, 2013.

  1. jkozacki

    Thread Starter New Member

    Mar 26, 2013
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    I am having a problem with a 12V DC axial fan cutting out under load. By load i mean blocking air flow. I am using this fan as a test bed of free air in different panels. I am under the assumption that the increased load on the fan causes it to draw to much current at start up. Once the fan reaches max rpm with no back pressure on it, it runs fine when you put the panels in place.

    equipment: 12V DC fan 2660 mamps 32 watts. 12V / 3.5 amp/hr sealed LA Battery. (when tha battery is fully charged its output is 13.5V)

    Is it as easy as putting a resistor in line? If so what size and power resistor should I use?

    Thanks in advance
     
  2. JohnInTX

    Moderator

    Jun 26, 2012
    2,346
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    It kind of sounds like your battery/wiring can't hack the 2.66A full load current. 3.5AH is not a really big battery to drive your load. If the battery is tired, it likely won't hold up for long. As they age, sealed LA batteries get to the point where they will drive light loads OK but can't hack their rated load, even when 'fully' charged.

    If the battery and wiring are really OK, then I'm not sure what your problem is. I haven't seen a 12V fan that won't run all day in free air.

    If you want to solve your LA battery problems for good, use an Odyssey. They are incredible. Actually, this site will have a better fit for what you are doing. Same technology, smaller packages.

    BTW Don't post the same question in more than one forum. We're not deaf.
     
    Last edited: Mar 26, 2013
  3. jkozacki

    Thread Starter New Member

    Mar 26, 2013
    3
    0
    thanks for looking at this,

    The battery i am using is from WERKER and is new and produces 13.5V at full charge. I am using 18 awg wire same as the fan leads. The problem isnt when the fan is pushing free air, it is when the airflow is restricted from start up. I have attached photos of the device so you could see how it is being used.

    thanks,
     
  4. JohnInTX

    Moderator

    Jun 26, 2012
    2,346
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    I don' see no stinkin' photos.

    Might help because otherwise, I don't know.. Have you measured the volts at the fan terminals when the problem occurs?
     
  5. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    In most cases cutting off airflow actually reduces the load a fan is driving. Put your hand over the pipe on a vacuum cleaner and the motor speeds UP because of reduced load when no air is fed to it. Pushing the air is the work the fan has to do.

    Not sure exactly what you mean. I do know most DC fans have internal ICs that regulate speed and limit current so that may be cutting in.
     
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