[dannzeman]

Check to see what the power output is on your laptop for each usb port and check to see if the computer is shutting off power to them to conserve the laptop's battery life. I checked both my towers and both my laptops and highest output I could find is 500mAh. That should be enough to charge the 800w under normal use, ie making phone calls or using as a modem. I use my 800w as a modem for 4-6 hours while at work and I have never seen it discharge while plugged in.