The current Pokemon Go mobile game made me upgrade my old 2200 mAh power bank. The old one was fine for charging one or two devices before running out of juice. Since I usually carry an iPhone, iPad and a 4G WiFi modem, I now need a new power bank.
Anker is bulkier than my previous power bank which is almost the size of a gum packet. Battery life is impressive, 22,100 mAh provides enough power for my mobile devices which means I usually recharge once a week.
Two USB outputs means I can plug in two devices at once for charging.
It seems that carrying a power bank nowadays is a necessity, and I always have mine in my daily bag.
Anker PowerCore 20,100 mAh – Ultra High Capacity Power Bank
Newer version: Anker PowerCore+ 20100 – Ultra-High Capacity, USB-C/Type-C