On occasions I found that the iPod battery wasn't quite large enough to cope with very long journeys. I wanted a way to improve this... So I grabbed a few batteries, clips, soldering stuff, bits of wire and a deck of cards.. This page is about what I managed to come up with...
First a little background stuff... The iPod is rated as 8-30 volts (or mine is anyway) and the Power Adaptor gives out 12 volts. I wanted to simulate the Power Adaptor as close as possible, so I figured I'd also give out 12 volts. Since that isnt a common value for Batteries I decided to combine two PP9's and two AA's. This is the circuit:
It was not entirely coincidental that these batteries just so happen to fit perfectly inside a playing card case. This is the one I used:
With a sharp knife I cut open the card case, and made sure that the batteries would fit. This is the arrangement I've put them in:
Next I cut out a shape in one of the bottom flaps for the Firewire socket. It's a regular 6-pin Firewire socket, which I bought from CPC. Then I stuck the firewire socket in place with some All-Purpose Adhesive from UHU. It now looks like this:
I figured that since it takes quite a bit of force to unplug a firewire plug that I should re-inforce the cardboard with more cardboard. Basically I made a little bit of card which held onto all the sides of the firewire socket and was also stuck to two sides of the card case. Then I made up the circuit using three PP9 clips and a 2x AA holder. Soldered it together and soldered it to the Firewire socket. Now it looks like this:
You can find the pinout for 4 and 6 pin firewire sockets (according to the IEEE1394 specs) on pinouts.ru - or a direct link: Firewire Pinout.
Then I placed the batteries back where they should go and tucked all the wires into place. Note that I also added a card strengthener on the lower left flap. It looked like this:
Then I got out my glue again and stuck the card case back together again. After the gue had dried it looked like this:
That's basically it! I measured the voltage out-put from all charged batteries and got 11.6. Not bad compared to the Power Adaptor's 11.7! I just use the lead that came with the iPod to connect the Battery Pack to the iPod and it worked fine. I find I get about an extra 10 hours iPodding time- depending on the batteries I put in it.
Several people have emailed me asking where to find firewire connectors, whilst I got mine from CPC, I have found that Farnell stock them, see these links:
Farnell Link One & Farnell Link Two
Note, this is an international company however the links are for the UK website.