Help me build a USB battery pack for Ipod touch G2!

Funny, I got an ipod as a gift but, I don't have a computer. I can only charge it at work but am limited to the amount of playtime (music, videos and games) outside of work.

I'd like to build a charger powered by preferably AA cells. Tried an AC charger for an older (non touch) ipod and that did not work. (I was informed that chargers that work for Generation 1 ipod touch doesn't necessairly work for G2 versions.) I tried building a charger out of a cell phone charger and a USB female connector but, that did nothing either. Connections here. I'm not too sure why...

Does the usb connection to the Ipod (G2) need to send some signal other than +ve and ground inputs for it to charge? Is the high unloaded voltage of the phone charger (>8V) the problem here?

I prefer not to buy a portable power supply while I can build one. Can anyone in here help me build one? (Although I'm ordering an original apple AC adapter, I'd still like to make the cell phone charger/female USB jack work since the apple adapter may not be here for another month.)

Thank you for your inputs.

eebowler.

Here is the ipod pin out info. http://pinouts.ru/PortableDevices/ipod_pinout.shtml

if you have a USB cable for it try getting a duracell mobile charger for it and use it as it works as both a AA cell smart charger and USB power device.

gorn, thank you. No. 27 of that article seems to be what I needed.

To charge an iPhone 3G / iPod Touch 2nd gen, usb data- (25) should be at 2.8v, usb data+(27) should be at 2.0v. This can be done with a few simple resistors: 33k to +5v (23) and 22k to gnd(16) to obtain 2v and 33k to +5v and 47k to gnd to obtain 2.8v. This is a notification to the iphone that it is connected to the external charger and may drain amps from the usb.

Click to expand...

why not just buy a wall charger for it on ebay?

I did. Paid for one from amazon. It should (I hope) be here in a months time. (I'm not US based and the same device here is $50 US.) I just wanted to build a portable supply from stuff available home... I'm a flashaholic, why buy when I can build? :rock: Considering the new information from above, I'm better equiped now to build a battery powered charger.

The information worked!! Using the cell phone charger was unsucessfull since (I assume) the voltage was too high but, the resistors worked with the power supply (from an old computer) since that had a voltage of 5.10V.

It's not going to be hard to implement this into a battery powered system now.

Good job. Glad I could help. I know how you feel about building your own. I like doing that myself.

eebowler said:

The information worked!! Using the cell phone charger was unsucessfull since (I assume) the voltage was too high but, the resistors worked with the power supply (from an old computer) since that had a voltage of 5.10V.

It's not going to be hard to implement this into a battery powered system now.

Click to expand...

They must have changed the ipod touch, then. The older ipods can take 5-30v in @ 1Amp (or so it says on the back of them).

~Brian