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Blue Wire Laptop Charger.. Help!

Discussion in 'General Electronics Discussion' started by Moh001, May 24, 2017.

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  1. Moh001

    Moh001

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    May 4, 2017
    i have laptop charger caple with three wires black blue white, i cut off the blue one and use the black and white to charge the laptop from 12v acid battery using boost converter 19.5v, the problem is the current is too high 3 to 4 amps!!! how can i reduce the current to 0.5 amp??? the blue wire for information i dont know how to use it with the boost converter.. when adding resisors the charging stops i think due to voltage drop.. help!
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Which current is to high? 2A to 3A to a laptop while charging it's battery seems reasonable. With the boost converter that could easily be 3A to 4A or even higher.

    If you remove the laptop's battery the current may be lower.
     
  3. Audioguru

    Audioguru

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    Sep 24, 2016
    The laptop or its battery has either a circuit to measure charging current then feed a signal on the blue wire to reduce the charger current or the blue wire connects to a thermistor in the battery that feeds the charger to tell it to reduce the current because the battery is getting too hot. That is why you should always use a charger that is designed for the product.
     
  4. Moh001

    Moh001

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    May 4, 2017
    when i measure the Amp whith the AC Adapter the current is 0.5 amp so i assume 3 amps is high, the boost converter gets very hot and even starts to smoke, i want the current to be 0.5 to 1, how?
     
  5. Moh001

    Moh001

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    May 4, 2017
    thank you,but i want to use acid battery to charge it, do you know how? i just know boost converter circuit but i have problem with current as u see
     
  6. davenn

    davenn Moderator

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    Sep 5, 2009
    you already have another thread on this subject

    this thread is closed
     
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