There are a few things to consider when shopping for a portable charger.
Ability: A power bank’s capacity is measured in milliamp-hours (mAh), but that can be a bit misleading as how much power you get depends on the cable you’re using, the device you’re charging and charging method (Qi wireless charging is less efficient). You will never get the maximum capacity. We try to provide an estimate of what you will get in terms of device charges.
Charging speeds and standards: Charge rate for devices like smartphones is measured in watts (W), but most power banks list voltage (V) and amperage (A). Fortunately, you can calculate wattage yourself by simply multiplying voltage and amperage. Unfortunately, getting that max rate also depends on your device, the standards it supports, and the charging cable you’re using. Many smartphones, including Apple iPhones, support the Power Delivery (PD) standard, which means you can use more powerful power banks to charge the device without issue. A few phones, like Samsung’s Galaxy S line, support an additional PD protocol called Programmable Power Standard (PPS) that goes up to 45W. Many phones also support Qualcomm’s proprietary Quick Charge (QC) standard. . There are other proprietary fast-charging standards as well, but you won’t usually find power banks that support them unless they come from the smartphone manufacturer.
To cross: If you want to charge your power bank and use it to charge another device simultaneously, you will need pass-through support. Nimble, GoalZero, Elecjet, Biolite, Mophie, Zendure, and Shargeek portable chargers listed support pass-through charging. Anker discontinued pass-through support because it found that differences between wall charger output and device charging input can cause the power bank to turn on and off quickly and shorten its life. We advise caution when using pass-through as it can also cause portable chargers to heat up.
Journey: It is safe to travel with a power bank, but there are two restrictions to keep in mind when boarding a flight: You must have the portable charger in your hand luggage (it cannot be registered), and it must not exceed 100 Wh (watt hours). If your power bank has a capacity greater than 27,000 mAh, you should check with the airline. Below that shouldn’t be a problem.