What is the best method for charging my iPhone using the juice pack?
Assuming the iPhone and juice pack are both fully charged, we recommend waiting until your iPhone has 20% battery left. When you're in the red, flip the standby switch to green and let the juice pack to do the heavy lifting. The iPhone requires more power to charge past 80%, so if you want to get the greatest battery boost from the juice pack, we suggest flipping back to standby mode until your phone battery is low again. This isn't the end-all-be-all, but we like it.