9 to 12 volt or 18 to 12 volt

Discussion in 'General Electronics Chat' started by nick_12, Jul 24, 2011.

  1. nick_12

    Thread Starter New Member

    Jul 23, 2011
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    Hi everyone, I know this is probably a dumb question but I'm a n00b.
    What would be more efficient and last longer: using a 9-volt battery and using a step up regulator to step it up to 12 volts; or have two 9-volts wired in series to produce 18 volts and then use a step down regulator to lower it to 12 volts.
     
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    Well, assuming a similar efficiency for a small step-up / step-down converter 2 batteries will last longer of course.
    If you have the space available why not buy a single 12V battery, like this one? ;)
     
  3. nick_12

    Thread Starter New Member

    Jul 23, 2011
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    ya tht would work to lol i didnt even think of tht. thank u
     
  4. Audioguru

    New Member

    Dec 20, 2007
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    The Energizer A27 12V alkaline battery is tiny so its capacity is only 18.9mAh when its load is 20k ohms (0.6mA to start) and its voltage drops to 9V.

    An Energizer 522 9V alkaline battery has much more capacity of 625mAh when its load is 270 ohms (33.3mA to start) and its voltage drops to 6.75V.

    A difference of 33 times the capacity. The 9V battery weighs 10.4 times more than the tiny 12V battery.
     
  5. iONic

    AAC Fanatic!

    Nov 16, 2007
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    Without knowing your power requirements or anything about your project it's difficult saying which choice will work best. The single 12V battery needs no regulation, but may not last long enough for your demands. Which is more efficient, stepping up or stepping down, I'm guessing but I think stepping down. And lastly, yes, if you can deal with 2 9V batteries in series and step down, you will have the longest lasting functional project.
     
    Last edited: Jul 24, 2011
  6. nick_12

    Thread Starter New Member

    Jul 23, 2011
    3
    0
    thank you for the replies. i got my answers
     
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