Power Bank- A Complete Guide To How To Choose

How to choose a power bank

I am pretty much frustrated when my smart phone batteries got empty. The same thing might happen with you all. Well there are two things you can do. First you will charge a smart phone or grab the power bank. Keeping in view i write this article “How to choose a power bank”.

But buying a good power bank is harder than you might think. Because of false advertising and paid review it is slightly confusing. So I am going to describe you some truth about power banks.

Smart phones have become our daily life companion and we need more and more battery life. Mostly a full charge is not enough for a day if you are a robust user. That’s why we should know how to choose a power bank.

The easiest way to expand your battery life is a power bank. But which one should you buy if you check out power banks on Amazon then you can find a lot of mixed reviews many reviews are paid.

In general, most people just search for the biggest capacity advertised for a low price. But this is something you should not do and the reason is that sellers mostly lie about the capacity.  

First let me explain how a power bank works and why you can’t simply divide your power banks capacity by a sound battery capacity and get the charging cycles.



Selecting a battery bank is not a small job but it is quite mind storming. Following topics will help you to know “How to choose a  good battery bank”.


So there are different kinds of power banks with different battery technologies.

Mainly two types of technologies are used in making battery banks. One is Lithium-ion technology and the other one is lithium polymer technology.


On the inside, cheaper power banks use lithium-ion cells especially the affordable 18650 cells. These cells are classified by its 18mmX 65mm size. They are cheaper and they are of size little bit larger than Lithium polymer batteries.

But well that’s the only advantage they have. A higher discharge rate just to get hotter and are not really durable compared to the new lithium polymer cells.

However Lithium polymer power banks are more expensive and also harder to get. But they are smaller and more durable on the long run.


Also the Lithium ion batteries can catch fire more easily because of their fluid electrolyte.

On the other hand Lithium polymer batteries use a solid or gel electrolyte and more safe.


Now let’s talk about the actual capacity. Because it gets tricky power banks get to 90% produced in China and most cheap unknown manufacturers of original manufacturer’s data tricky about the battery capacity.

So that’s a fact but although the capacity advertised is not the actual capacity that goes into your battery bank.

So first the capacity inside is measured as mAh that stands for milliamp hours and tells you how many milliamps or amps you can drain from the battery in one hour.

So for instance a 10,000 milliamp hour battery means you could drain 10,000 milliamp to one hour or for instance 1,000 milliamps for ten hours draining capacity.

But you can only do this at the rated voltage of the cells and most cells are rated at 3.7 volts. If you multiply a million amps and the rated voltage you get the actual energy.

 Which would be three point seven watt hours that means you can drain three points seven watts for one hour from the battery. But why do we need to know all that.

So you need to know that USB ports are made to operate at five volts. So you always plug a smart phone into five volt source. This is the output of the normal USB port of your notebook or phone charger.

So inside of the power bank the voltage has to be stepped up from the three point seven volts to five volts using a boost converter.

This conversion is not loss less that means there is a conversion loss to calculate. The root capacity takes the advertised power bank capacity times three point seven and divided by five this is how your real capacity calculated. And it’s always lower than the advertised capacity of the power bank.

The second factor is the efficiency factor.

And this one depends on your power bank. Cheaper power banks have a bad converter inside that transforms a lot of energy into heat which is lost by power bank. In high quality power banks have better up stepper resulting in a small loss.

So good power banks lose minimal and give you more power than worst quality power banks.

Let’s say 20% in some and 30% or way more in some power banks.

 Now let’s do the math. Your 10,000 mAh power bank at frequent cell walls actually can only supply seven thousand four hundred million AMPS at five volts.

And if the converters crap then maybe even less and maybe in a couple of months even more less because it sounds alter gradually with time.

So if you thought that you could charge your 2000mAh and you do not found five times with10,000 NH battery then you will disappointed because it just has 5900 mAh coming from with power banks.

Use B port and there is another conversion in your smart phone back to 3.7 volts. So this advertised 10,000 mAh power bank will charge a smart phone only around 2.5 times.

Also 10,000 mAh capacity power banks are common in use than other power banks. Because it is very handy and easy to carry.


Generally power banks come with 2 charging USB ports.

One is 1 A and other is 2.1A.

5V/1A port is used for smart phones because it needs around 1A current for charging.

5V/2.1A port is used for tablets because it needs some high current to be charged.

Today you can find 04 port or 05 port power banks with high capacity devices which enhances the charging capabilities of 4 or 5 devices simultaneously.


Now a day’s fast charging is one of the main features of battery bank. This specification is very useful in our day to day work and travelling. You can charge your smart phones with 18W fast charging speed.

In reverse how fast your battery bank recharges itself is also important. So check specifications more accurately with these features.


Outer Casing is also much important as inside features. Outside casing should be attractive and durable. Normal Plastic casing can brake easily and catch fire. So go for hard plastic casing or silicon fiber casing.

External casings also available in market for extra cover and precaution to your power bank. You can purchase it and use it if you casing is not so durable.



·       Don’t use your smart phone or other devices while it is in charging condition. Because by doing this you are making the battery in line with the phone and it causes higher power draw and excessive heating of your device and power bank. If it is made up of Lithium ion technology then you should be more careful. Because it can explode and catch up fire. It may harm you or make a big fire incident.

·       For health benefits also you should not use your smart phone while it is charging. Because during charging if you will use your phone than battery chemicals may leak and harm you.

·       Battery may bulge in size and you can notice the swelling of your phone and power bank.

·       Charging capacity of your smart phone and power bank may decrease gradually and prone to unserviceable in frequent use.

·       You can get an electric shock during charging.

·       Radiation from your smart phone increases during charging. It will affect your health and may cause cancer.


So be careful during usage of power bank and choose wisely during purchasing of such devices from market. Stay healthy and enjoy your life.

Have a good day.



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