Find all your DIY electronics in the MakerShed. 3D Printing, Kits, Arduino, Raspberry Pi, Books & more!

2619837795 42E1812426 O
2620661734 06Fb96188D O
Some nice iPhone charge up hacking

Phillip Torrone

Editor at large – Make magazine. Creative director – Adafruit Industries, contributing editor – Popular Science. Previously: Founded – Hack-a-Day, how-to editor – Engadget, Director of product development – Fallon Worldwide, Technology Director – Braincraft.



  1. man says:

    i need this charger urgently…….what should i do

  2. Ben White says:

    I want to know how to get hold of that charger app!

  3. samurai1200 says:

    this is just voltage division, no? what happens when the iphone stops accepting current? resistors melt?

  4. xun says:

    Thanks! I just modified my 3600mAh USB UPS battery charger to make it work with my iphone 3g, and it’s working great!

  5. PsRon says:

    It doesn’t take 4 resistors to make a 2-tap voltage divider.

    3 resistors in series, from +5 to Ground:
    +5 to “D-” = 47k
    “D-” to “D+” = 10k
    “D+” to Ground = 39k

    I found that my USB charger actually put out 5.25V (not exactly 5.0V) – but it worked anyway… I got 2.7V and 2.2V measured on my unit, and it went into charge mode fine.

    With 5.0V, these values calculate to give 2.44V and 2.03V output. I imagine many of these chargers are in reality a little over 5.0 V output anyway.

    YMMV :-)