Saturday, April 11, 2009

DIY IPOD Battery Pack

So my IPOD Nano 1st G internal battery is dying. I can barely squeeze out a few minutes of play time using the normal Apple firmware. IPOD Linux and Rockbox are awesome; by setting the backlight brightness to a minimum, I can get a whole lot more playtime. One option is to buy a battery and installation kit (they’re pretty inexpensive). However, this method requires you to open up your IPOD (which is really not that big of a deal), but there must be a simpler way of getting the job done – using components you can find around the house.

What I’m talking about is an external power supply/battery pack that can fit onto any IPOD (through the USB cable) -

But we can make one ourselves – a more versatile one.

The IPOD cable consists of one end that plugs into the device and the other end is a standard USB male connector. The USB connector consists of 4 pins - V+, GND, D+, D-. To supply power to the IPOD, we need to supply exactly 5 volts through the V+/GND pins. The D+ and D- should be tied to V+ via 100k resistors (I think – more on this later). And there you have it – your own power ipod power supply.

The actual circuit, however, can get a bit complicated. What regulator do we chose? The design I’m thinking of will be able to be powered from as little as 2 AA batteries to the 12 V output from your car. We need a regulator that can accept this high range of voltages. Obviously it needs to be a boost/buck (step up/step down) regulator. These tend to get a bit annoying as we need external capacitors and solenoids for the circuit. Take a look at the mintyboost above for inspiration.

Oh, and it would be cool to have it small enough so all of it fits on the back of an IPOD Nano 1st G.


Just a thought.

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