When looking for a power bank there are lots of features, brands, and models available to choose from. Some have more features than others, some charge their batteries faster than others, and some last longer per charge cycle than others. But one thing is for sure capacity is what matters the most.

You’re probably used to seeing power banks with all sorts of different mAh from 2000 mAh, 4000 mAh, and up to 10,000 mAh or even more. This article will discuss why capacity is important and what it means for you when choosing a portable power bank.

What is the Capacity in a Power Bank

Capacity refers to how long the power bank will power a device before needing to be recharged and is measured in milliamp-hours (mAh). This is derived from batteries and is the amount of energy charged in a battery that will allow one ampere of current to flow in one hour. In conventional batteries, it is indicated as Amp-hours (Ah) but because power banks are smaller units milliamp per hour (mAh) is used.  

Technically a battery with a 20Ah used with a device that consumes 1 amp of current continuously will operate at 20 hours. This is the same as saying a 20,000 mAh power bank will power a 1000 milliampere battery for 20 hours.

When Calculating Capacity the following formula is used

Capacity (milliampere/hour) = discharge (milliampere) x discharging time (hour)

Using Watt-Hours (Wh)

Using (Ah) of the battery alone isn’t sufficient to explain what a power bank can do, especially if you are using some energy conversions like DC-AC chargers or an inverter. For this Watt-hour (Wh) is used. Most power stations which are large power banks will be rated by watt-hours and will also have an indication of the maximum watts you can pull from the battery. This is a good indicator of the appliances it can power and how long it can run those devices.

Watts multiplied by hours gives watt-hours, a measure of total energy consumed over time.

What is the Best Capacity for a Power Bank

So what is the best capacity for a power bank? When picking a power bank it is recommended to choose a power bank that will power your device twice over and not just act as an extra battery. So, if your phone battery has a capacity of 4,000 mAh you would need a power bank with twice the capacity (8,000 mAh) to charge your phone completely charge one time and reserve for another use.

If you charge several devices then you should estimate how long you will need the extra pack to power those devices before the next charge.

How fast will a Power Bank Charge my Phone

There are some differences in how fast a power bank will charge your device, the main difference in charging speed is due to the output power. This is how much power (measured in Amps) you can get from a power bank. In general, most phones require 1-2 amps of current to recharge at a 5V voltage, with some exceptions. This should be indicated on the phone charger that you bought your phone with.

Most power banks will have a 5v USB output will produce which is between 1A and 2.1A for most power banks. A 2A charger will charge your phone faster than a 1A charger. 

Charging your power bank

This is how much power you can input to a power bank (measured in Amps). For example, your device’s wall charger might be 1 Amp or 2 Amps, but if you’re charging from your computer it could only be 0.5 Amps. As you can imagine, it’s difficult to get 5 Amps into a power bank (for example) if you’re only getting 0.5 Amps, while charging via your computer or laptop.

Input also includes the maximum current that will pass through the micro-USB cord connecting the power bank to your device. The longer and thicker the cord is, generally speaking, the more amps you can send.

Other Features to look out for 

While we have covered Capacity and output as important features to look out for. There are others that should not be overlooked. While choosing a big capacity power bank is ideal you will also need to be mindful of the size and the weight. If you are doing light traveling you will not need a big power bank to weigh you down that may need a lot of space. 

If you are also looking to power multiple devices including your camera or laptop you will need to look out for the ports that will charge these devices. We recommend you look at the Maxoak 50,000 mAh Power bank to power your devices including laptops and phones.