Anker’s PowerCore 13000 though sits in a sweet spot. To break it down simply, mAh is a measurement used for battery capacity, the PowerCore 13000 has, well, 13000 mAh, and your iPhone has around 2000. Of course other (*cough* most *cough* Android) phones have larger batteries so you’ll get 4-5 charges out of a PowerCore 13000 on those devices. Having two chargers on the PowerCore 13000 is particularly useful since it doesn’t support quick charging in either direction. Also, it’s worth getting the PowerCore 13000 in your hands a week or two before a trip to make sure it’s working properly.