Power Packs: Emergency Power
Portable power packs (also known as external batteries/chargers) come in all shapes and sizes, but they do essentially the same thing: allow you to charge a USB-powered phone, tablet, or other device one or more times.
With so many different types, it’s not always obvious which features matter. Here’s a suggestion to what you need to look for when buying a portable power pack.
The most important question you need to ask is: what are you hoping to charge, and how many times? A tablet requires more power than a smartphone, and charging multiple devices (or one device several times) needs a higher-capacity battery.
An easy way to work out your basic needs is to look up the capacity of the battery that’s already in your device. This is measured in milliamp hours (mAh) -- the iPhone 8, for instance, has a 1821mAh battery, while Android smartphones like the Samsung Galaxy S8 are typically between 2000 and 3000mAh.
As long as your portable charger comfortably exceeds that number, you’ll get at least one full charge out of it.
A few good examples are: