Even though these will stop charging, it is best not to leave the battery charging once it has finished. The sooner you take the battery off the charger once finished, the better. NEVER leave a battery unattended while charging i.e while you sleep or leaving the house as it charges.
I'm also not crazy about using a computer's USB ports to charge anything or use a PT. Use a wall adapter or powered USB hub instead.
If you want to use the X2 as a PT, you will need to use the 1.5 Amp wall adapter - Smokeless Image | Only The Best Electronic Cigarette | Volt - USB Wall Adapter 1.5A - Accessories If you just want to charge it, then any wall adapter rated 500ma will work. You can find them just about anywhere, including WalMart.
oh ok thanks, I will probably just go ahead and purchase the wall adapter, seems like a good investment and just 10 bucks more. no need to buy a usb charger since those are just for the slim batteries.