1. AZ_Mike's Avatar
    I was testing the actual charging ability of 3 brands of Li-Ion boost mode chargers.

    I used a 12v to 5v buck mode switching power source (3A) as the reference. I found that none of these boost mode chargers live up to claimed currents (did it with and without data pins connected). I used both a current measuring app and a mechanical amp meter so you could see the phone trying different draws out with the flick of the needle.

    Faced with 5V and D+ connected to D-, the S4 will start drawing ~1A (about 1.05A) and then work it's way up to 1.2A testing voltage along the way. It does not look like it will try to any higher than 1.2A. If voltage is too low, it drops to about 460mA and starts testing upward in increments until it settles on a draw (about 660-800 for these various 1-2A rated boost converters). 2 were single port, one claiming 1A and the other claiming 2A, One was dual port and may be an honest total number because the Samsung found an increment it liked at about 660 mA (750mAx2=1.5A claim?)

    The price of this knowledge was high. I slipped and briefly expose the USB port to 12v on the +5v line. Now I have a phone that will charge standard charge (app says 460mA) but will not fast charge and will not make a USB data connection.

    Is there a circuit breaker, fuse, or replaceable USB module? I'm guess I am lucky that I can use my phone and charge at all.

    My second G4 (work phone) still fast charges and connects to USB so I know I damaged my personal phone.

    05-06-2015 07:20 PM
  2. AZ_Mike's Avatar
    I think this is the part I need: does anyone have any feedback?

    05-07-2015 03:24 PM
  3. Green_Laser's Avatar
    As for being able to go back to charging, the solution below may be of use to you, however for connecting the phone to a pc for quickly transferring files you may be out of luck and might have to send through a cloud service or Bluetooth etc.
    For going back to being able to charge your phone:

    Have you tried swapping out the back panel for a wireless charging one and charge it wireless?

    I think they sell them on the AC store, I recommended it once to my brother who also has an S4
    05-11-2015 03:02 PM

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