Apple iPhone charging at wall USB port
An AC-wired USB port can deliver power at up to twice the speed of a conventional charger and four times the speed of a laptop's USB 2.0 port.
9 Ways to Charge Your Smartphone Battery Faster
Plugging into your computer may be the slowest way to charge your smartphone battery.
When your smartphone battery power runs low, it's time to plug it into your laptop for a recharge, right? Not so fast ... literally. Pulling power from your laptop's battery or through the machine's power cord will charge up your smartphone, camera, music player or USB-connected small device, but it will take a while.