1. toolman911965

    Thread Starter New Member

    Apr 8, 2010
    12
    0
    Hello all, I have a simple circuit using a cr2032 3v 225mAh battery and a 5mm red LED rated at 20mA with a potentiometer up to 10k ohm. I am trying to figure out how long the battery would last at full power (basically without the potentiometer in the circuit) and my electronics is very rusty. Can anyone give me some idea as to how long I can expect this battery, assuming full charge, would last. Thanks in advance.
     
  2. #12

    Expert

    Nov 30, 2010
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    It depends on the internal resistance of the battery, as that's the only limit that is happening. Watch for smoke.
     
  3. bertus

    Administrator

    Apr 5, 2008
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    #12 likes this.
  4. #12

    Expert

    Nov 30, 2010
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    Beg to question. That pdf doesn't say the battery has 1k of internal resistance. It says the maximum happy current is 3ma.
     
  5. Tealc

    Member

    Jun 30, 2011
    140
    10
    The battery will actually discharge at a current larger than 3mA. It's probable that it'll damage the battery and reduce it's capacity dramatically if you exceed the stated max though. I've only held LEDs on them for a couple of minutes at most and they drive them seemingly greater than 20mA but not enough to create a lot of heat and damage the LEDs.

    Makes me wonder though how long the battery would last too.
     
    #12 likes this.
  6. #12

    Expert

    Nov 30, 2010
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    What's that signature line I saw? One real data point is worth a thousand expert opinions?

    Thank you, Tealc.
     
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