Capacity - one of the most important criteria, which you need to navigate when buying. It is will determine how long your mobile device will remain offline until you get to the outlet.
In order for the external battery to cope with its task, it is necessary to choose an apparatus whose capacity is at least twice the same indicator of the battery of the phone or tablet.
1. The battery capacity of a good smartphone is about 3000 mAh, which means that it requires an external battery for 6