Series-Parallel Battery

Discussion in 'The Projects Forum' started by Lightfire, Apr 24, 2011.

  1. Lightfire

    Thread Starter Well-Known Member

    Oct 5, 2010
    690
    21
    Hello,

    Okay, here I am again. :)

    Okay, as 2 batteries in parallel is not sufficient is not enough to make these two bulbs to light fairly, okay I made now a parallel-series batteries.

    Materials

    -Four batteries AA (2700 maH, right?:p)
    -Two bulbs and their own sockets (bulbs specs: 2.5V/0.3A)

    Okay,

    Firstly, is my connection of series-parallel batteries correct?
    Secondly, will the bulbs brightness will be fairly to each other if I will make that connection battery?

    Thanks.

    Lightfire

    I forgot to post the attachmetn! O_O
     
    Last edited: Apr 24, 2011
  2. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Two batteries in parallel will only double the amount of current. Batteries in series will increase the voltage, which is what will make the bulb glow more brightly.
     
  3. Lightfire

    Thread Starter Well-Known Member

    Oct 5, 2010
    690
    21
    Great!

    But my series-parallel connection is correct?

    Thank you!
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Your series-parallel connection is wrong!

    You have two cells on the left side in parallel making 1.2V and you have two cells on the right side in series making 2.4V. If you connect the two groups in parallel then you will probably have a fire!

    The two cells on the left side are supposed to be in series like the other two cells, not in parallel. Then you can safely connect the two groups in parallel.

    2700mAh AA cells are Ni-MH. They can supply 2500mA to 2700mA for 1 hour. Two cells in series can supply 600mA to light both light bulbs for 4.5 hours. Two series groups in parallel can light both light bulbs for 9 hours.
     
  5. Adjuster

    Well-Known Member

    Dec 26, 2010
    2,147
    300
    @ Lightfire: Take note of what Audioguru has said. These small rechargeable cells can deliver quite a lot of current in the short term. Certainly enough to do damage.

    Actually, putting any batteries in parallel carries some risk. Even if they have the same nominal voltage, unless they are all charged to the same extent there can still be trouble. The general problem is called "circulating current".
     
  6. DigitalReaper

    Member

    Aug 7, 2010
    70
    2
    You could just connect everything in series, bulbs and batteries. That would give you 6v split between both bulbs, the only (probably minor) issue being if one bulb blows both will go out.
     
  7. Audioguru

    New Member

    Dec 20, 2007
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    2700mAh AA cells are Ni-MH which are 1.2V to 1.25V nominally each. Then four in series make 4.8V to 5.0V, not 6V.

    I think high power LEDs should be used, not incandescent "heaters" that waste a lot of battery power by making heat instead of light.
     
  8. Lightfire

    Thread Starter Well-Known Member

    Oct 5, 2010
    690
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    O_O

    Haha, I forgot that. :)

    OK, first, it's not an recheargable battery. It's an LR6/ALKALINE battery. :)

    second, here's my new battery!
     
  9. Lightfire

    Thread Starter Well-Known Member

    Oct 5, 2010
    690
    21
    Is my new battery correct?
     
  10. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Lightfire, I don't see much of a difference. The batteries are still in a parallel-series configuration. You should NOT have any batteries in parallel--only series.
     
  11. Audioguru

    New Member

    Dec 20, 2007
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    The batteries are now wired correctly and produce 3V at 5400mAh when the cells are new.
    It is fine to connect brand new battery cells in parallel.

    Your series-parallel cells will power two 300mA light bulbs for about 4 hours when the 6V battery voltage will drop to 4.8V and the lights will be dim.
     
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  12. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Really? Oh, I'm sorry. I guess I've been wrong about that all these years :confused::p
    Thank you for clearing that up.
     
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  13. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
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    Batteries is parallel can be isolated from each other using diode isolators. The marine industry uses them. The drawback is obvious, as you will drop a minimum of .7V across the diodes, which is meaningful when working with 1.5V cells.
     
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  14. Audioguru

    New Member

    Dec 20, 2007
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    I measured 16 brand new Duracell AA (LR6) alkaline cells. Their voltages were mostly 1.596V but ranged from 1.593V to 1.599V. They will be fine when connected in parallel.
     
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  15. Lightfire

    Thread Starter Well-Known Member

    Oct 5, 2010
    690
    21
    Okay.

    Thank all of you.
     
  16. ddurgin

    New Member

    Mar 2, 2011
    4
    1
    2-parallel - 2-series should be OK as long as the parallel pairs are close in voltage when paired. 1 - 2 tenths of a volt diff is OK, 0.5V diff may cause some heat (the lower one will look like a fairly low impedence load to the higher cell). That config will have twice the current capacity though if that's what you need.

    Good luck, & Be careful! even small batteries can produce enough power to burn you.

    DD
     
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