About Battery

Discussion in 'General Electronics Chat' started by chuyenle, Jun 18, 2013.

  1. chuyenle

    Thread Starter New Member

    Jun 5, 2013
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    My circuit using batteries to power the 555 timer. I measure the voltage across the batteries before pressing the button is 11V and after pressing the button, when the LED is on is 10.5V. I want to know what value should I look at to know when the batteries get close to be fully discharged: before the button is pressed or after, when the system is running.
     
  2. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    You'll need to tell us what size and chemistry of the battery. For example, size AA chemistry alkaline. Also, you can easily find discharge charts in the internet for almost any battery. If I were going to answer your question, that's the first thing I would do.
     
  3. chuyenle

    Thread Starter New Member

    Jun 5, 2013
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    It's 8 D size battery, alkaline. The discharge chart I found shows one battery discharge rate. But because I'm using 8 of them, I don't know if that chart can be applied. Also, my system has sleep mode that still drain the batteries (although very little). The load takes about 250mA.
     
  4. Shagas

    Active Member

    May 13, 2013
    802
    74
    Well if you found that chart for 1 battery and you have them connected in series then you just multiply by 8 . So if they are dead at 0.9 volts then 8 in series would be dead at 7.2
     
  5. Brownout

    Well-Known Member

    Jan 10, 2012
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    I agree, if all the batteries started out new.
     
  6. chuyenle

    Thread Starter New Member

    Jun 5, 2013
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    Thank you very much for all the help:)
     
  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,395
    1,607
    Well they certainly all end up old.
     
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