We know that plugging the iPhone 4 via USB takes longer to charge it than a standard wall charger, What you might not know are the exact numbers of this comparison, so take a look at When Will Apple’s post about it.
“Stating the obvious, 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, taking 4 minutes 49 seconds.
Obviously the convenience of USB charging is great, but if you are in a rush to get charged and get out of the house always go for the outlet.”
[via iSpazio]