Two parallel voltage sources? What happens?

Discussion in 'General Electronics Chat' started by John5788, Jul 8, 2009.

  1. John5788

    Thread Starter Active Member

    Apr 2, 2009
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    0
    I am curious what happens in a circuit like this:

    [​IMG]

    PSpice wont let me simulate it, gives me an error.

    What would happen if I built a small circuit like this? Does the 12V just end up charging the 5V battery?
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    There will be a large current from the 12 Volts battery to the 5 Volts battery,
    that is only limited by the internal resistance of the batteries.

    Greetings,
    Bertus
     
  3. Jony130

    AAC Fanatic!

    Feb 17, 2009
    3,957
    1,097
    Added a small resistance in series with both voltage sources.
    Then PSpice will simulate this circuit
     
  4. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    Have you done any network theorems?

    You can solve this using superposition, Kirchoff or Thevenin.
     
  5. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    I doono about charging the battery but it will definitely blow it up in practice :D

    Rifaa
     
  6. viip

    Member

    Apr 16, 2009
    23
    0
    practically due to internal resistances current will flow in to 5v battery....but still i think am gonna try it....lets see how will it smell during blowing job [:D]
     
  7. millwood

    Guest

    I would put a resistor in serial with one of the batteries, like 10ohm 10w, or something like that.

    batteries have very low internal resistance (from a few mohm to 30-50mohm, depending on the type). a 5v voltage drop over this kind of resistance will cause massive amount of current.

    I see sparks, :).
     
  8. hobbyist

    Distinguished Member

    Aug 10, 2008
    764
    56
    1.) Who knows, since it's 2 electrodes seperated by a electrolyte, maybe initially it would act like a capacitor??? Before overheating......

    2) .But then again when you do dc analysis (superposition) on it you replace it with a short.
    So it would be a low value resistor in parrallel with the 1 K.

    I say, # 2. is my final answer...
     
    Last edited: Jul 8, 2009
  9. Von

    Active Member

    Oct 29, 2008
    65
    0
    Batteries are not equivalent to electrical "shorts".

    Why do you expect it to ACT like (or simulate) one?

    Do it outside!
     
  10. millwood

    Guest

    they are, at least during a short burst.

    if you were to parallel two batteries, the current going from the high voltaged one to the low voltaged one will just be the voltage differential / total internal resistance of the two amps.

    in this case, the total internal resistance is likely in the .1ohm range, and the voltage differential is 5v. so you are talking about a 50amp current flow.

    spark!
     
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