Phone Charging

Discussion in 'General Electronics Chat' started by Michael Nusair, Oct 27, 2015.

  1. Michael Nusair

    Thread Starter New Member

    Oct 21, 2015
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    is there any way to make a usb cable that cuts the power when the phone gets to 100%?
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Doesn't your phone do that internally? Every one I have owned since ~ 1980 does.
     
  3. Michael Nusair

    Thread Starter New Member

    Oct 21, 2015
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    i want to do it in the cable. so that the phone will fell disconnected
     
  4. MikeML

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    Oct 2, 2009
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    How will the external circuitry determine the state-of-charge of the internal battery when the battery terminals are not accessable without cutting holes in the cell phone?
     
  5. Michael Nusair

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    Oct 21, 2015
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  6. ian field

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    Oct 27, 2012
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    Many phones flash up a battery full indication - a photo cell could detect that and trip a breaker circuit.

    It would be unwise to tamper with the battery circuitry in any way - most phones use lithium cells, and those can catch fire if the charge control goes wrong.
     
  7. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Sounds like a microprocessor (powered continuously by the USB) monitoring an inline current-sensing resistor and a MOSFET to disconnect the power when the charge current level drops.

    Ken
     
  8. MikeML

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    It is totally unnecessary. Wonder if it is a scam?
     
  9. KMoffett

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    Agree!

    kEN
     
  10. AnalogKid

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    Aug 1, 2013
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    Or a comparator (no microcode).

    Or the standard current shunt plus transistor base-emitter junction current sensor driving the series pass transistor. Two transistors, 3 resistors, and one cap, but 0.6 V drop across the sensor. Germanium?

    ak
     
  11. #12

    Expert

    Nov 30, 2010
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    This makes about as much sense as adding a hose designed to turn the gas station pump off when my gas tank is full, and attach it to the gas station hose that already does that.o_O
     
    Sinus23 likes this.
  12. recklessrog

    Member

    May 23, 2013
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    ha ha! so true!
     
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