About all of you know that USB charging of mobile device takes more longer time as compare to standard wall outlet charging. So, folks at whenwillapple has conducted a test on iPhone 4 charge time through USB and wall outlet charger and according to them:
“The iPhone 4 takes longer to get a full charge on USB than an outlet. What you may not have realized is how big the difference was, an extra 30 minutes! That’s 23% longer to get a full charge on the USB. If you’ve ever had a completely drained iPhone, you know it takes a bit of time before it turns back on. Plugged into an outlet, it took 3 minutes 11 seconds to come back to life. On USB it took almost 2 minutes longer, 4 minutes 49 seconds.
Obviously the convenience of USB charging is great, but if you’re in a rush to get charged and get out of the house, always go for the outlet.”
iPhone 4 Charge Time Outlet Vs. USB