Device that knows when a battery is charged?

Discussion in 'General Electronics Chat' started by Shoester, Apr 21, 2011.

  1. Shoester

    Thread Starter New Member

    Apr 21, 2011
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    Alright, quick question for you guys....

    Does such a device exist that knows when a battery is fully charged, and can then do "work" when that happens?

    IE, a device that closes a circuit when it detects that the battery has reached full capacity?
    Say, a regulator charges a battery, and once the battery has been fully charged up, this "device" closes the circuit and the regulator can no longer send power to the battery.

    Does such a device exist?

    Thanks guys!
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Yes.

    It is commonly called a 'worker'. They are usually paid very little money for performing such important work..

    :)
     
  3. Shoester

    Thread Starter New Member

    Apr 21, 2011
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    Ha! Touche....
     
  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    A voltage comparator could do this, if you could build the circuit. You might need some trial and error runs before you find the proper voltage level that represents a fully charged cell.
     
  5. Shoester

    Thread Starter New Member

    Apr 21, 2011
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    Excellent idea! Another idea also just dawned on me...I'd like some input on it as well.

    If I were to hook up a multi-LED battery level indicator, with the last LED signifying a fully-charged battery, and run a circuit back to a relay in the charging wire that when recieving power from the FULL POWER LED would shut the relay, cutting off flow to the battery.

    Does this make any sense?
     
  6. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    You would need some kind of signal 'conditioning', to make the LED drive voltage compatible with a relay coil. This might be easier than building your own comparator.
     
  7. Audioguru

    New Member

    Dec 20, 2007
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    Not a single hint about whether the battery type is lead-acid, Ni-cad, Ni-MH, Lithium-Ion, Li-Po, alkaline or a few more types that I don't remember. The charger circuits are all different.

    Most semiconductor manufacturers make battery charger ICs that do everything and you set the type of battery with a few pins. If it is set wrong or if you use the wrong charger then you might have a fire.
     
  8. designnut

    Member

    Apr 21, 2011
    33
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    lead acid cells are cuttoff when a voltage is reached. wet cell nicadsare charrged at a set voltage and cutoff when the charging current drops, then the charginng voltage must be lowered. Smart chargers like the La Crosse read the Nimh or solid Nicad cell voltage and when it decreases insteead of increasing stops charging.
     
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