Heating 800 watts nichrome wire with a battery.

  1. hi guys.. i'm new here and this is my first post.. my friends told me that the title of this post is impossible and i need a car battery to heat the 800W nichrome wire, and i believe them.. they also said that AC will solve the problem.. but i need to use DC so i came up with using diodes.. the problem is the setup.. i'm not familiar on how to connect those stuffs so anyone here who have a heart to help a dumb like me.. just a simple diagram using a 800 watts nichrome wire, a plug, and diodes.. i'm afraid i might create a bomb so please do help me.. thank you in advance..
     
  2. jcsd
  3. jim hardy

    jim hardy 4,820
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    Yes the wall plug can electrocute you.

    A car battey can explode which will spray battery acid in your face.

    A red hot nichrome wire near upholstery or plastic underhood parts can start a fire,

    what is it you are trying to accomplish? Maybe someone can help.
     
  4. sophiecentaur

    sophiecentaur 13,705
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    What do you need 800W of hot wire for? Sounds a bit 'industrial'.
     
  5. i just want to heat the nichrome wire using direct current to compute the temperature it can produce and not to heat something.. my problem is a safe setup of heating the 800watts nihrome wire using DC..
     
  6. Integral

    Integral 7,345
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    The wattage developed by your wire will depend upon the voltage applied. At what voltage does it generate 800W? What you really need to know is the resistance of the wire. Given that we could tell you more.
     
  7. NascentOxygen

    Staff: Mentor

    Why not buy a factory-made one which is connected up and ready to go? That way you don't need to risk safety with dodgy wiring. It's a simple electric toaster. :biggrin:
     
  8. sophiecentaur

    sophiecentaur 13,705
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    For a lab experiment you can get excellent results with 24W from a 12V source. Easier and safer. 1kg of water is about right.

    if you just want to get the wire hot then you really don't want to have a damned great lethal coil of red hot wire to deal with. Do it with a short length and a low voltage (C cell), briefly. How would you plan to measure the temperature? In air it should get red hot - what temperature would that represent?
     
    Last edited: Mar 18, 2012
  9. power: P = V*V/R
    resistivity: p = R*A/L

    measure your wire's diameter, and look up it's resistivity, and you'll be set

    also, doesn't PF not deal with dangerous topics? shouldn't this topic be locked?
     
  10. sophiecentaur

    sophiecentaur 13,705
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    I'm inclined to agree with you. (Do as I say, not as I did?)
     
  11. it's not a matter of "do as I say not as i did" so much as "do it the right way"
    there is a right way for amateurs to experiment with high voltage, high temperature, highly acidic compounds, etc. they first need to do research- in books!
    a forum is NOT the place to learn things; the internet barely is.
     
  12. sophiecentaur

    sophiecentaur 13,705
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    You are right of course. You certainly can't believe what you see with experiments on YouTube and any idiot could be giving advice in a forum.

    (I'm glad that you were so well behaved in your youth. Wot, not a single scar?)
     
  13. thanks for the replies..
    @Integral- i bought the nichrome wire with its wattage already set..
    @sophiecentaur- i can't find a 24W nichrome wire.. suppose i cut the 800W nichrome wire, will that reduce the wattage?..
     
  14. NascentOxygen

    Staff: Mentor

    Is this a roll of uninsulated wire? How many metres long? Can you unwind a few metres and determine its resistance/metre? If not, why not? :smile:
     
  15. sophiecentaur

    sophiecentaur 13,705
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    I think he understands so little about this that it is clearly dangerous for him to continue with it. He appears not to have a clue. Steer clear.
     
  16. There is no fixed value of 'temperature' given the specification of a "800W Nichrome wire". A stable temperature is achieved once power in (800W, assuming you set the voltage correctly) equals power out (heat flow). So, the answer depends on what is surrounding the wire (vacuum, still air, flowing air, copper tube, etc. etc.) and their steady state temperatures. The hottest would be in a vacuum, where the wire will turn red to white hot before it melts. In still air, red hot is likely to be the upper limit. As noted, this can be dangerous, and your lack of knowledge of basic electronics has people concerned for your safety. Just because the wire says '800W' does not mean that is the limit of the wire. Choosing the wrong voltage could exceed this greatly. Note also that the resistance of Nichrome varies with its temperature (like all metals), but you can search for this variation on the web. Do not assume a measured resistance at room temp is going to be the same when its red hot.
     
  17. mfb

    Staff: Mentor

    This is maximal value, the actual value depends on your setup.

    You clearly do not have the required knowledge to do this safely. We won't help you to kill yourself here.
     
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