A:
Once the Mophie on one the phone there is a switch on the back that will turn it on or off. You can charge both at the same time through the regular port and on the back at the bottom there are 4 LED's giving you an indication of how much power is left.
Once your phone's batter is low you flip the switch and it will start charging.
*power button cap must be removed because it will press the phones power button constantly.
**you cannot sync the phone to your computer with the case on despite what says in the description. When you plug it in USB it does come up but after 15-30 seconds will disconnect... then reconnect.... then disconnect... so you have to take the phone out to do that.