So the other USB thread got me to thinking about the limitations I've seen with electronics that charge via USB ports.

I have a variety of things that can charge via USB.

smart phone
flip phone
GPS
iPod
lights
etc.

What I have observed however, is that most of them do NOT charge from a typical USB adapter. I also have poor results attempting to charge them from a radio or flashlight with a USB charging port (while cranking of course - have to do it at the right speed). I get the best results when I load the specific driver on a laptop and charge them directly from there.

I've tried cigarette outlets to USB adaptors where you use your own USB cable and they don't charge the phones or GPS. However, I can use a simple AC/DC inverter to plug my laptop or netbook into the car, then connect a USB hub and charge all of them at once.

Examples of limitations:
** I can't get my GPS to charge via USB on anything but a computer or it's specific cigarette to USB adapter. The generic cigarette to USB adapter in which you connect your own USB cable will power it up in a mode in which it tries to "connect" to a computer. But does not charge.
** My smartphone won't charge on anything but its AC adapter, designated DC adapter or a computer with a USB port and drivers installed.
** A standard basic Motorola flip phone with USB charging port will charge off my computer, designated wall adapter, and one of my crank flashlights. But another crank radio will not charge it. Nor will the generic cigarette to USB adapter in which you connect your own USB cable.

In summary - If you think you have found a "system", you had better TRY IT out on everything you intend to use it on to make sure it works.