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Discharge time of 2 capacitors in parallel

Discussion in 'General Electronics Discussion' started by Ping, Feb 9, 2016.

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  1. Ping

    Ping

    4
    0
    Feb 3, 2016
    Hi,
    Can someone please tell me if this is correct?

    If I put 2 capacitors in parallel in a DC circuit, the capacitance adds and the total ESR is the inverse of the two ESR's added, just like any other resistance. Therefore to get the quickest possible discharge rate I need 2 capacitors with the highest possible ESR.

    Is that right? If not, someone correct me!
     
  2. Ratch

    Ratch

    1,073
    327
    Mar 10, 2013
    You need to get your understanding of ESR checked and calibrated. ESR is an AC phenomena, and is a measure of the lossiness of capacitor. You need to read and understand the mat4rial in this link. http://my.ece.ucsb.edu/York/Bobsclass/194/References/General/ESR of Capacitors.pdf

    Ratch
     
  3. Ping

    Ping

    4
    0
    Feb 3, 2016
    Good article Ratch. Thanks - although much of it is beyond what I'm trying to do.
    So you mean that all the dissipation factors will slow the discharge?
    And if I put 2 capacitors in parallel will the total resistance still be the sum of the inverses? Will that make the discharge faster?
     
  4. Ratch

    Ratch

    1,073
    327
    Mar 10, 2013
    Are you talking about the RC time constant? Depending on what kind of capacitor you have, the physical resistance should not be more than a few ohms. How does that compare with the other resistance in the circuit? Is it worth worrying about? If necessary, I can calculate the response of two capacitors and their physical resistors in parallel, or one double value capacitor and resistor in series. I think probably the additional resistance in the circuit will swamp out any of the capacitor physical resistance no matter how you configure them..

    By the way, you mentioned capacitor discharge. What is the capacitor discharging? Before the capacitor discharges, it has to charge with something. What is that something? Anyone?

    Ratch
     
  5. AnalogKid

    AnalogKid

    2,349
    658
    Jun 10, 2015
    Since your question are not clear, can you post your schematic? It will save a lot of time.

    ak
     
  6. supertech007

    supertech007

    5
    1
    Feb 28, 2014
    A capacitor of a lower uf rating will discharge faster if the voltage remains the same
     
  7. Ratch

    Ratch

    1,073
    327
    Mar 10, 2013
    Voltage is its rating. Value in microfarads is its capacitance value, not rating. What is the capacitor "discharging"?

    Ratch
     
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