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Quick DIY Portable iPhone 3g Charger

Posted on Friday 22 August 2008

I’m going to the desert for a week and wanted a way to recharge my iPhone. I bought a zap rx4-c, which works with most of my other devices, only to learn that it’s not compatible with the iPhone. Zap’s customer service was friendly but they should change their description in two ways: One, you can use regular AA batteries with it for living out in the field for a long time (yay!), and two, it’s not compatible with the iPhone or iPod Touch (boo.). The iPhone requires a 2.4V and 2.8V reference signal on the data pins for it to charge…Crafty Apple! Zap is coming out with a cheap adapter for the Rx4 but I needed something right away.

There are circuits out there for converting the 5V to the proper data pins and voltage, but I already had a 12V car adapter that would supply them. So instead, the goal was to supply 12V to my car adapter with batteries.

The solution:

2 6V lantern batteries
Alligator Clips
Female Car Adapter
iPhone Car Adapter
Cardboard Box

If you wire the batteries in series you get 12V. It works fine, though the adapter whines pretty loudly which worries me a little. Also, I am aware that batteries encased in paper and cardboard are a slight fire hazard. I’m only going to charge this outside while I’m watching it. (Any advice is appreciated, this isn’t much different than how the iPhone charges in a car is it?)

Thanks to Fred for his help conceptualizing this.

1 Comment for 'Quick DIY Portable iPhone 3g Charger'

    August 22, 2008 | 4:31 pm

    that is awesome.
    you are awesome.
    *pushes glasses up nose*

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