Creating a cable for fast USB charging
When I was in US last time, I picked a nice charger with it’s own backup from Amazon. It’s PowerGen charger with a storage capacity of 8400mAh with two USB ports for output (one with 2Amps output and other with 600mA with 5V standard USB).
This is a amazing product since 8400mAh is really huge amount power. My phone’s battery has a capacity of 1750mAh and theoretically speaking this can charge battery from 0 to full around 4 times.