Using the Goal Zero Sherpa 15 power bank is a breeze. First, make sure it's fully charged using the included micro USB cord. You can plug it into a USB port on your computer, a wall adapter, or any other USB power source. Once it's charged, connect your phone to the power bank using the built-in micro USB or Lightning cable. The power bank will start charging your phone automatically. When you're done, just unplug your phone. As for maintenance, keep the power bank in a cool, dry place. Avoid exposing it to extreme temperatures or moisture. If you're not going to use it for a long time, it's a good idea to charge it to about 50% and then store it. And remember, don't try to open the power bank yourself as it could damage the device and void the warranty.