Collection: Portable Charge House

Fast Charging

Another factor to consider is how quickly 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.

The two main fast charging standards you're likely to encounter are USB Power Delivery and Qualcomm's Quick Charge. Power Delivery (PD) is a newer protocol in which two compatible devices negotiate on the fastest charging option available. It also allows for power to flow both ways.

Quick Charge, on the other hand, works by increasing voltage rather than amperage. This standard allows you to charge supported phones to 50 percent capacity in 30 minutes, which is especially helpful when you need power in a pinch.

Keep in mind, your phone will only take in as much power as its charging circuit is designed for, so even if you have it plugged into a 5V/2A battery, if it's only able to handle 5V/1A, that's the rate it will charge at.