I would not recommend trying to charge anything via charge21.sh with USB plugged to computer. AFAIK, charge21 tries to pull more "juice" that regular USB ports allow (500 mA). At best, operating system will disable port and shout at You, at worst, You'll burn fuse of port in use (or all ports - actual outcome depends on motherboard implementation - good ones will just shout, bad ones got burnable fuses or even one fuse for all ports).

/Estel