Guide to the Best Power Banks

Most of us can’t live without our mobile phones and rely on them more and more each day, whether we like them or not. Nowadays, we use our phones not only for receiving and making calls and text messaging. We also use our phones for video chats, playing games, using social media, playing games, online shopping, and live streaming. Mobile phones have become the platform for communication in the modern world. Businesses also rely on apps for mobile productivity and connectivity. We also need access to our laptops, tablets and other devices while we are on the go.

The prevalence of gadget owners has increased the use of phones in public places such as streets, restaurants, train stations, etc. You can see people with their heads down who seem very busy using their phones and tablets everywhere you look.

We all know that all these devices run on batteries. And as we also know too well, those batteries eventually run out of juice. And when you’re out of the house or office and on the go, it can be challenging to stay powered up. Public spaces are becoming more accommodating to making charging stations available but depending on where you’re at, including out in a remote location, plugging in may not always be an option.

Fortunately, because of advanced technology, we all enjoy means that battery technology has also advanced.  The development of the easily portable power bank has been a boon to anyone who is frequently on the go, traveling for extended periods, or living off the grid.

So, what is a power bank?

A power bank is a portable power source that contains one or more rechargeable batteries and has input and output ports. They are generally small enough to fit into a pocket, and the weight usually varies depending on the capacity. However, if a power bank claims a high capacity but a very low weight, one of the numbers is likely incorrect.

This is because a power bank is powered by battery cells, similar to the AA batteries that are inserted into flashlights or other electronic devices. These rechargeable batteries are connected in parallel to increase the overall capacity. If the capacity is high, it requires more batteries to achieve that number. If there are fewer batteries (for less weight), then the capacity is necessarily lower.

Because of how the batteries are connected and the type (lithium-ion or lithium polymer), they could overheat. Manufacturers make it, so the charge circuit manages the voltage, but cells could be damaged or faulty and result in an explosion. This means that choosing power banks that are of good quality is very important.

Understanding a power bank’s capacity

It’s essential to understand the secret behind the power bank’s capacity so that you can buy one that will suit exactly your needs.

You might have noticed that a 10,000 mAh, which should charge your 2,500 mAh battery about four times (from 0 to 100), charges 2 to 3 times only. If you’re confused, this is because mAh is not the right unit to measure battery capacity when the voltages of the power bank and charged devices are different. For example, most power banks use Li-ion batteries that output 3.7 volts (nominal). But the battery in your phone gets charged at 5 volts.

This creates a massive mismatch and might leave you disappointed that you aren’t getting the expected battery life out of your power bank.

Therefore, watt-hours or mWh is the right way to measure your power bank’s batteries’ stored energy as it is voltage-independent. Let’s do simple math for a better understanding of this process.

Consider a power bank of 20,000 mAh. It has 20,000 a mAh capacity at 3.7 volts.

20,000 x 3.7 = 74,000 mWh

Now, after dividing the total mWh of the battery by 5V, you will get 14,800 mAh. This might be the actual capacity of a 20,000mAh power bank.

In addition to the energy lost while converting 3.7 volts to 5 volts, several other factors need to be taken into account, such as ambient temperature, the resistance of the connecting cable, etc.

So, let’s assume there is a 10% loss or 90% efficiency.

14,800 mAh x 0.90 = 13,320 mAh.

13,320 mAh is approximately 2/3 of the on-paper or advertised 20,000 mAh capacity of the power bank.

As the actual charging performance will vary from device to device, you should assume 2/3 capacity of the number advertised on the power bank.

Let’s consider an example of the Anker PowerCore 26800 Portable Charger. Suppose its real-world efficiency is 66%.

26,800 x 0.66 = approx. 18,000 mAh.

Hence, it can charge an iPhone 8 (having a capacity of 1,820 mAh) for:

18,000/1820 = about ten times!

A quick rule of thumb is to assume that your power bank has a real-world capacity of 2/3 of the capacity advertised on the package or site.

Essential factors to consider before buying a power bank


You are here because you are in search of a high-capacity power bank. As you may already know, a power bank is measured in milliamp-hours (mAh), and your average smartphone has a 2,500 to 3,000 mAh battery. The larger the power bank’s capacity, the more juice it will provide to your devices for a longer time.

And if you also want to charge your tablets, notebooks, or charge your laptops, you want one with more than 50,000 mAh of capacity.

Power Delivery

Today’s smartphones use various charging tactics to make the charging process more efficient. From wireless charging to quick charging, there are a lot of things in between. Please ensure the power bank you are interested in provides at least 5V/2.0A through its wired ports. If it allows for only 1A, it might be almost useless due to how slow it will charge your device.

If you have a phone that supports wireless charging or quick charge, you should get a high-capacity power bank that offers at least one of these two options. Many latest power banks come with an 18W fast charging port; hence you can get one that offers it.


Since a power bank will be your best friend that you will be carrying from one place to another, you want it to be fairly portable. It should fit in your backpack or laptop bag with ease.

The bigger the power bank’s capacity, the heavier and bulkier it will be. However, many brands have considered this concern, and these power banks are both high-capacity and have a sleek design.

Charging considerations and dangers

USB ports usually charge at 5 volts and .5 amps. When the voltage does not change, but the amperage increases, the potential flow of energy also increases. This results in a faster charge for the device and faster discharge for the power bank, as long as the device supports it. Because devices pull current rather than pushing it, there is no problem plugging in a device that uses less amperage than the port can support.

However, when the power bank discharges faster, it increases the heat in the battery. Hotter batteries are less efficient and may result in less charge overall.

Turn the phone or other device off for the best results when charging. Charging on a faster port is usually best, but especially if it becomes necessary to charge the device while using it; otherwise, it will likely continue to drain despite the added power.

Choosing a power bank that supports pass-through charging is good when it is often necessary to charge a device at the same time one is charging the power bank; both items can charge with one power source with this type of battery.