No "fear" more ago ...

empty cell phone batteries. Also Tablets will load properly on the go. I have the battery subjected to an endurance test. A total of four devices (3 smartphones, a tablet) I had loaded on more than 2 days only with the EasyAcc. A third day would have the PowerPack probably not have survived, but four devices are also not normal case ;-)
A single smart phone with all the battery-guzzling services (3 / 4G, WiFi, GPS) can certainly get by a good week without power plug with this unit.