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    It is an ideal solution to protect rechargeable batteries from deep discharge. It gives an LED indication when the voltage level in the battery drops below 5.1 volt.
    CA 3140 Op Amp is used as a comparator with a zener to fix voltage in its non inverting input. Preset VR1 set the voltage level just below 5.1 volt at the inverting input. When the battery voltage is above 5.1 volt, zener provides regulated 5.1 volt to pin3 of IC and its output goes high to light LED. It indicates that battery is full. If the voltage in the battery drops below 5.1 volt, output of IC turns low to switch off LED.

    Battery Indication circuit diagram

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    6 Responses to "Low Battery Indicator Circuit"

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    1. yarra vijay says: on July 15, 2010 at 5:54 pm

      i want know about ca3140 applications

    2. I will Post the details of CA3130

    3. Thank u sir for giving an idea.

    4. i have a doubt can i replace opamp ca3140 with IC 741 for this application. I stimulate this circuit in multisim by using opamp 741. it shows result our requrement. is there any practical problems by using 741.

    5. djzohn says: on August 28, 2012 at 12:06 pm
        member

      hello sir, can i add this circuit to my inverter circuit to indicate low battery? Because i think this particular one is designed for 6v battery, if not kindly post that which can be used for 12v, and possibly one that can automaticaly cut off, once the voltage is bellow 10v. Thanks

    6. Dear mohankumar,
      iwant automatic(auto cutoff if battery full charged using relay and led indicator) charger circuit.and low battery indication.
      kindly sent to my email.

      thanks…

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