How to get +12 and -12 from car battery.

Discussion in 'General Electronics Chat' started by Metalica, Aug 1, 2010.

  1. Metalica

    Thread Starter New Member

    Aug 1, 2010
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    I have an audio amp and it requires +12VDC , 0(ground), and -12V DC to power it.
    So is it possible to get the above voltages from a cars battery.
    Is it possible to get these with out transformers(I.e inverters).



    Thanx


    [​IMG]
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    If you used two 12v sealed lead acid batteries in series, that would work.

    Don't use automotive or marine battery inside a dwelling, as they will emit hydrogen and osxygen gases.

    If you're planning on using it in an automobile, then you will need an inverter (negative DC-DC converter) to supply the negative portion.
     
  3. Metalica

    Thread Starter New Member

    Aug 1, 2010
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    Yeh so i guess their is not other option then to use an inverter, since the car has only one battery supplying +12 with reference to the cars body.
    Could their be some other way to get -12 v and +12v from the cars batter to power the above diagram......?
    No inverters plz..................
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    Nope, you're out of luck then.
     
  5. tom66

    Senior Member

    May 9, 2009
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  6. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    How much current do you need for the -12V? If it is only a few mA, then there are devices, such as the ICL7660A, that will do that. You could also consider carrying a separate, smaller battery for the -12V.

    On the topic of safety, I think the risk of using a lead-acid battery, particularly a sealed lead-acid battery, in a dwelling is a bit overstated. Certainly, an explosion in a garage would be serious, and it is quite common to have batteries and to charge them there. Explosions are rare and almost always result from doing a dumb thing. In addition, less than 1% of hydrogen produced by a sealed battery is released (http://www.vonwentzel.net/Battery/00.Glossary/). Production of relatively tiny amounts of hydrogen in a home is not dangerous. All homes are ventilated. Moreover, humans produce on average about 1.2 L of hydrogen per day per person*, and there has never been a home explosion related to that -- even in homes filled with people and pets.

    John

    *Calculation:
    1) 361 mL of hydrogen per day in our flatus (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1378885/ ; and http://www.heptune.com/farts.html)

    2) Roughly 850 mL of hydrogen per day in our breath (http://www.ncbi.nlm.nih.gov/pubmed/9925135 ; and http://www.arb.ca.gov/research/resnotes/notes/94-11.htm)
     
  7. Metalica

    Thread Starter New Member

    Aug 1, 2010
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    0
    OK thanx for all of your inputs.
    the page about SMPS were very interesting.
    And the thanx jpanhalt" for the links of hydrogen gas emitions.
    I resolved the above issue by buying another 12 V audio amp kit.
    thanx
     
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