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Why battery’s internal resistance decreases with temperature?

  1. Aug 23, 2012 #1
    Hi,

    Does battery internal resistance obey the general resistance-temperature rule?

    For metal, resistance usually increases with temperature (see wikipedia).

    For batteries however, its internal resistance decreases with temperature (also see wikipedia).

    Could anyone explain the contradiction?


    Bob
     
  2. jcsd
  3. Aug 23, 2012 #2

    trollcast

    User Avatar
    Gold Member

    The resistance of any galvanic cell such as a battery decreases as temperature increases due to increased electron mobility at higher temps.

    The increased electron mobility means that the electrochemical reactions inside the cell can happen faster or easier (not sure which one it is, someone else might know) which means the internal resistance is effectively reduced.
     
    Last edited: Aug 23, 2012
  4. Aug 23, 2012 #3
    Then they are consistent. Thank you!

    Bob
     
  5. Aug 23, 2012 #4
    Batteries are chemical devices that rely on chemical reactions to produce their 'electricity'.

    Chemical reactions mostly obey the Arrhenius equation which says that the rate of reaction increases with temperature.

    http://en.wikipedia.org/wiki/Arrhenius_equation

    So the faster the reactions the better the current transport and the lower the effective resistance.

    Note that the cell voltage is only weakly dependent on temperature.
     
    Last edited: Aug 23, 2012
  6. Aug 23, 2012 #5
    Studiot,

    I just read the wiki article and got a better understanding. Thanks!

    Bob
     
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