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What makes a good high current micro-usb cable?

Discussion in 'General Electronics Discussion' started by Kenneth Tan, May 22, 2015.

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  1. Kenneth Tan

    Kenneth Tan

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    May 22, 2015
    I've recently bought 10 micro-usb cables. Tested them and all charged my Galaxy S4 @ 920mA. (Very nice)

    The cables had two problems. After a while the cable broke, just a centimeter from the microusb connector.
    I have ordered some new solder micro-usb connectors from China through ebay.
    After replacing them on the cable, the charge current decreased to 460mA. (Almost exactly half)

    Only two wires (black & Red) were connected in my replacement, in the original setup all 4 were connected.

    Any idea why the charging current is halved?
     
  2. Gryd3

    Gryd3

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    Jun 25, 2014
    USB charging specifications dictate how much current is drawn by a device.
    Because the replacement only has the power wires and not the data wires, your device and charger cannot communicate to be able to allow charging with more current. It's imperative that any high current charging applications use the signal wire pair to communicate with the charger to be able to take more than 500mA.
     
  3. Kenneth Tan

    Kenneth Tan

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    May 22, 2015
    Thanks for the quick reply.
    A Google search for 'USB charging specifications" got me the result I needed.
    http://www.maximintegrated.com/en/app-notes/index.mvp/id/4803

    if I'm correct in interpreting the text, I should short D+ and D- for maximum charge current.
    The USB interface in the phone should test this circuit (resistance to short) to what chargestate it should function.
    I will make a short in the connector and report the results.
     
  4. Gryd3

    Gryd3

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    Jun 25, 2014
    That is not always a 'standard' that is followed.
    If not a short, some devices require a resistor, or voltage divider to be in place on the D+ and D- lines.
    You seem resourceful though finishing up the answer by doing your own research, so I thank you for that and wish you the best of luck in making it work for you.
     
  5. Kenneth Tan

    Kenneth Tan

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    May 22, 2015
    Gryd3 likes this.
  6. Gryd3

    Gryd3

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    Jun 25, 2014
  7. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    We like that here at Electronics Point!
     
    Arouse1973 likes this.
  8. Kenneth Tan

    Kenneth Tan

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    6
    May 22, 2015
    And here are my results:
    Only Vcc and Gnd to Galaxy S4: 460mA
    As above, but with D+ & D- shorted (on phone side) : 1100 mA
    As above, but with 2x 100K resistors between Vcc an GND + D-Short to the middle of the resistors: 1100mA (I did not have 82K resistors)

    Current ratings are averages.

    So in the end it only needed a short between the data points on the connector. Thats good, because it would have been a heck of a job to squeeze two 1/4W resistors into that small connector housing.

    Case closed.
     
  9. Gryd3

    Gryd3

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    Jun 25, 2014
    Thank you for the update, and welcome to Electronics Point!
    I hope to see you around here more often.
     
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