Making a solar powered gadget recharger

I'll be the first to admit that I don't know what I'm doing here, and I'm probably going to fry the circuitry of hundreds of dollars worth of gadgets before I learn anything. But I think it'll be worth it. I bought a couple of these solar-powered AA battery chargers when my family and I moved to Rarotonga in 2003. They worked quite well.

I recently came across the chargers in storage and decided to see if I could use it to recharge my iPod, digital camera, and cell phone. It figured it would come in handy as a device charger when I cut the power to my guest house.

All of these can be powered using USB, or though an appropriate Zip-linq USB cable. I had a spare female USB extension cord laying around, so I clipped off the male end, stripped the wires, and soldered the red wire to the positive side of the solar charger and the black wire to ground (I found out what the different colored wires were for here).

It's been very hot and sunny here in Los Angeles this week, so it was a good time to test this device out. I plugged my iPod Nano into it, and for a brief instant, the recharge icon flashed, but then it went dark. I do know that power is being transmitted through the wires, though, because when I plugged a USB-powered LED lamp into the charger, it lit right up.

My next step is to buy some good rechargeable batteries (the ones I have are spent) and charge them with the charger. Then, I'll see if the stored charge in the AA's will charge the iPod. I'm not sure if they will, because the batteries are connected in parallel, not series.

Also, I wonder about the potential for damage to my devices. I don't mind sacrificing some of my stuff in the name of learning, but there's no reason to kill my iPod if it can be easily avoided. I'm thinking of incorporating Limor Fried's Minty Boost circuitry into my charger to protect my devices.

If you have any ideas or advice, I'm all ears.