As smartphones become more and more prevalent and multi-functional, it has quickly replaced several gadgets, for instance, an iPhone can be used as a camera with its high megapixel resolution, a MP3 player with access to all kinds of music, and an eReader using Amazon’s free kindle app. Besides, now most people seem to have their phone permanently attached to their hand. Therefore, having an easy access to a charger becomes more important than ever before, and there are various brands of chargers out in the market for you to choose. Before settling on a certain choice, let’s review some more information on power banks.

Which features do we need in a Power Bank?

Watching your phone or tablet steadily run out of juice when you're nowhere near a power outlet is abysmal. It would be a blessing if there is a third-party backup battery to use. Power banks come in every size and capacity to keep your device going when your battery icon starts to dip in the red. And it doesn't end there. Some power banks are equipped with features like fast charging, wireless charging, built-in cables, AC adapters, LED flashlights. And what we need to know is the real functions behind those descriptions.

Size and Capacity

Generally speaking, the bigger the battery, the higher the capacity and quantity of ports you get. Power banks that fit comfortably in your pocket are typically good for a full phone charge or two, while anything designed to keep you going all day is going to require a bag or a purse.

On the pocket-friendly front, most smaller batteries that maximize portability have a capacity of 3,500mAh and under, which gives you just enough charge to top up most phones once.

Once you get above 3,500mAh, battery size increases to the point where it's less likely to fit into your skinny jeans, but can still be stowed in a jacket pocket.

Input and Output Ports

The type of port (or ports) a battery has determines not only whether it is compatible with the devices you want to charge, but also charging speed. At a minimum, most battery packs will have a standard micro USB port for input and a USB-A port for output. But with more phones, tablets, and laptops adopting the USB-C standard, you'll often find a USB-C port in addition to USB-A.

USB-C generally allows you to charge faster, consolidates input/output to one port, and can be found in many new phones. Now, you do have to be careful, because while some power banks have USB-C input, they don't have USB-C output. On the Mi Power Bank Pro, for instance, plugging a USB-C device in results in that device trying to charge the battery rather than vice versa. Make sure that both the port and cable you use are up to spec.

Fast Charging

Another factor to consider is how fast a power bank can charge your phone. Battery output is measured in voltage and amperage. Amperage (or current) is the amount of electricity flowing from the battery to the connected device, while voltage is the amount of potential energy. Multiplying volts by amps gives you wattage, the measure of total power. In order to make a device charge faster, most manufacturers either vary the voltage or boost the amperage in order to increase the total wattage. For most fast charging, you're looking at boosting or dynamically varying the voltage.

Essentially, for any kind of fast charging you need three things: A phone or other device with a charging circuit capable of using one of the fast charging standards, along with a battery and cable that support the same standard. If any one of these three things is missing, you won't be charging as fast as you can.

Recommendations

Based on the above introduction, here below is our recommendation today for the best portable power bank for travel--Zendure X6 Power Bank and Hub. 

Capacity: X6 powers iPhone and Galaxy up to 6 times, offers 1.1 charges to 12'' Macbook, and 3.2 charges to Nintendo Switch.

Input and output: 45W Power Delivery USB-C Output/Input: Equipped with the latest PD fast-charging technology, X6 provides full speed charging for your MacBook, iPhone X, iPhone 8 Plus, and Nintendo Switch. Recharge X6 5X faster when using Zendure 63W PD Charger.

Fast charging: Charges QC 2.0/3.0 equipped devices up to 80% in 35 minutes (such as Galaxy S7, S8 Plus, Note 8), thanks to ZEN+ 2.0 smart quick charge port.