I've made a USB powered PV which is basically the
thread that was posted here but is just a battery box with a 510 batt connector and a atty.
A few of things I'll point out here:
I am not that knowledgeable of electronics so take my advice with a grain of
salt.
First, it does not work on all USB hosts. I've tested my USB PV'er on my desktop computer which is about 1 year old and it works. I've tested it on a powered usb hub and it works and then stops until a few seconds later. And I've tested this netbook. It works but XP complains about overcurrent. I've tested this on a inverter with a USB jack
Power Inverters from Black and Decker and it does not work at all.
Secondly, and probably due to my limited success is the USB dedicated charging standard mentioned in the USB howto
thread. That basically implies that the USB host must comply with the charging standard.
Thirdly, you need to realize that the atty is going to draw more current than the USB is able to supply even if it is USB Charger standard compliant. So, it'd probably be wise to design the USB passthrough to prevent it from drawing more than 1.5A. By drawing more amps than the usb host can supply you have the potential (no pun intended) to damage your motherboard but, imo, more likely your USB hardware on the motherboard. Regular 510 attys have about 2.2ohms of resistance. I = V/R = 5v/2.2ohms = 2.72amps. So you probably want to add some resistance to the circuit to limit the amperage to 1.5A.
