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Heating element

Discussion in 'General Electronics Discussion' started by Buddhalogic, May 11, 2014.

  1. Buddhalogic

    Buddhalogic

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    May 11, 2014
    I have 8aa batteries hooked up to

    http://m.ebay.com/itm/231216889753

    With potentiometer set to 9 volts
    My meter reads to specs
    I add several different pieces of steel filteres mini to mid size

    Everytime voltage drops to .501 at 2.5 amps. What am i missing.




    Im thinking power is going back to the board. Is there a something that i need to add to neg side?
     
    Last edited by a moderator: May 11, 2014
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    I think you are attempting to draw too much power from the AA batteries and the voltage is collapsing.

    Having said that, I'm unsure of what you're trying to do and what these steel filters are.
     
  3. Buddhalogic

    Buddhalogic

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    May 11, 2014
    I just to make hot air in a small space my later design imply this part with coles to this voltage load. Thing is i adde aanother pack of batteries and up the potentiometer same results. So that 16 aa.

    Do i need a power up instead of a dowstepper. N then have a regulator on that?

    When attached to my voltage machine at work itheat element at these voltages and amps had no provlem
     
    Last edited by a moderator: May 11, 2014
  4. davenn

    davenn Moderator

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    Sep 5, 2009
    all great looking power supplies, but I don't think you read or understood what Steve said to you

    AA batteries are not going to supply the sort of current requirements you need

    look to a 12V sealed lead acid/gel battery say one of at least 7.2A /hr

    cheers
    Dave
     
  5. Buddhalogic

    Buddhalogic

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    May 11, 2014
    Okay would you know a distributer that sells something like that in bulk?
     
  6. Buddhalogic

    Buddhalogic

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    0
    May 11, 2014
    I need someone who sells single cells so i can link muriple
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    I still really have no idea what you're trying to do, or why a battery is not as good as single cells.
     
  8. Buddhalogic

    Buddhalogic

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    May 11, 2014
    The purpose is a portable device that i can heat the steel screen so it over 300-400 degrees which is just under red.

    I was planning on using the large A batteries that we usr in movie industry portable ionac bateries from each pach had 10 of these and last 6 hours with 12 v 1 am load an can handle way above 36v output at 5 volts.
    I only wana use 4-6 in my product
    But i dono who makes these as cells i have are blank. My engineer has a batterie person but i wont hear back for a week there on vacation.
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    OK, so we've gone from aa to A.

    DO you know the resistance of this steel screen and the current you need to pass through it to get it to the required temperature?
     
  10. Buddhalogic

    Buddhalogic

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    May 11, 2014
  11. Buddhalogic

    Buddhalogic

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    May 11, 2014
    Had a problem with the screen getting some more clean ones.

    So cant test till tomorro but question. Is There a way to not have voltage collapse. Or will switchin to the A batteries work. The thing is effectevly heated to what tempature i need at 12 v 3 amps.


    And yes it seems to want to try an pull as much as it can
     
  12. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    ok, lets assume you need 12V at 3A.

    That means the resistance of the screen is 4 ohms. 4 ohms sounds huge to me, but you are the one who measured it, right?

    Now lets assume that each AA cell is capable of 500mA whilst maintaining a voltage of 1.2 volts.

    This means you will need 10 AA batteries in series to maintain 12V at 500mA. But you need 3A, so you'll need 6 of these in parallel.

    The simple answer is that you will need 60 AA batteries to drive this load.

    No form of step up or step down SMPS is going to change the amount of power you require or change the amount of power you can get from an AA battery.

    If that sounds outlandish then look at the information you have supplied. I can do no more than go on what you have said.

    I am most dubious about the figures you have given us for the screen. However, I also don't know how long this device must operate on a set of batteries, and if that operation is continuous or intermittent. I also don't know whether you would want this to depend on using a high energy (expensive) battery technology or if you want it to run from cheap supermarket brand cells.

    Anyway, I hope this gives you something to think about.

    Oh, and also, many of the specifications you haven't stated will affect the allowed current from the batteries. Once you have been more specific you can look up some battery datasheets to give you more exact answers.
     
  13. Buddhalogic

    Buddhalogic

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    May 11, 2014
    Thank you very much now i understand clearly whats going on an how to most likly adress. Going to order some better batteries bossibly change heat element design and ull be back if i get stuck again. Thank you soo soso much



    Ye this may be a high load but this is only on for 8-15 sec max



    These are what we use at our work i think that it should be sufficiant
    http://www.wickedlasers.com/image/wicked/pdf/SANYO-UR18650A-2.2Ah Specifications.pdf
    3.5v at 2400mA
     
    Last edited: May 13, 2014
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,171
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    Jan 21, 2010
    I'm not sure where you get 3.5V at 2400mA. But great job on the datasheet. This makes things much easier.

    If you look at the datasheet, the normal current is 2.15A and the max is 4.3A. Since you're only operating intermittently, I think that 3A would be fine for short periods.

    Looking further into the datasheet, you're looking at between 3.25V and 3.75V per cell for the majority of the discharge curve.

    The question you need to ask yourself is: Is it acceptable to operate at a voltage which might be 15V when the batteries are fully charged, dropping to 13 when they're close to discharge (that's 4 cells). If that's too high, is 11.25V dropping to 9.75V too low? If either of these is acceptable then you're OK to go without any form of regulator.

    If you need to test, I would recommend placing a 6A fuse in series with the batteries... Just in case.
     
  15. Buddhalogic

    Buddhalogic

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    May 11, 2014
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