[HELP] LED indicator for battery charging [HELP]

Discussion in 'The Projects Forum' started by pr1111, Nov 25, 2011.

  1. pr1111

    Thread Starter Member

    Jul 8, 2010
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    I have a nokia charger and a battery. I want to charge the battery when it is not connected to the phone, just the battery itself. Can somebody help me on how can I put 2 indicating LED when it is charging and full charged.
    Thanks in advance for those who are willing to help.

    [​IMG]
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Better buy a standalone charger than trying to build one, it will be cheaper
     
  3. pr1111

    Thread Starter Member

    Jul 8, 2010
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    i am going to connect it to a project... I will use the nokia battery as a source for the project and use the nokia charger to charge our project.
     
  4. Audioguru

    New Member

    Dec 20, 2007
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    You forgot to tell us any important details:
    1) Is the battery chemistry lead-acid, Ni-Cad, Ni-MH or lithium?
    2) What is the mAh capacity of the battery?
    3) How long does the charger take to fully charge a dead battery?
    4) Do you have a circuit that senses the battery voltage then disconnects the load when the voltage becomes low?
     
  5. pr1111

    Thread Starter Member

    Jul 8, 2010
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    It is a Nokia Battery BL-5c, Li-Ion battery with a 1020mAh of power.
    It can be full charge for 2 hours when inside the phone. I have no idea for the circuit. I just want to have two LED that indicates if the battery is charging and when full charged. The circuit will be connected where the charger supply the input and the output goes to the battery.
     
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Li-on charging is tricky.
    U will need a good working schema for it if you don't wanna kill ur battery
     
  7. pr1111

    Thread Starter Member

    Jul 8, 2010
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    is charging the battery directly from the charger bad??
     
  8. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Not from charger but making an off the shelf one is tricky.

    Using charging voltage to light LED's is tricky too since we dunno the exact charging current at any given time, this is bad since LED's is an additional load
     
  9. Audioguru

    New Member

    Dec 20, 2007
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    The old Nokia BL-5C is a single-cell Lithium battery. Yours might be so old that it works poorly.
    Its nominal voltage is 3.7V and is 4.2V when fully charged and is about 3.0V when the charger circuit in the phone should disconnect its load.

    You don't have a charger, instead you have a power supply for the charger circuit that is inside the phone.

    If you attempt to charge the battery without using the proper charging circuit then the battery will probably explode or catch on fire!

    Go to www.batteryuniversity.com to learn about charging a lithium battery cell. They have a graph that shows its voltage slowly increasing to 4.2V while its current is limited then a long time occurs at 4.2V when the battery is still charging. So you cannot use a simple voltmeter to determine when the cell is fully charged. The charger circuit disconnects the charger when the battery cell is fully charged.
     
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