How Power Bank Works – Principles and Concepts Explained

Cell phones, tabs and other gadgets nowadays are having so many applications which correspond to higher energy consumption that the battery charge cannot last long. Thanks to power banks; we can use our phones and gadgets in the whole day without the need of an AC power. Let us uncover how power bank works.

Types of power bank


Non-portable power banks are stationary. They are mostly with very high storage capacity, high power that is used a temporary backup power in households, offices and establishments.


Portable power bank is the one that is can be carried by the user wherever he/she wanted to go. Famous example is the cellphone power bank that nowadays is very famous.

The two ways of charging your gadgets

1. Through a charger that is connected to a wall outlet

This is the common method of charging you electronic gadgets when you are at home. You will plug the charger to the wall outlet and the charger output port to your gadget.

how to charge a phone

2. Charging your phone or gadgets through a power bank

When you are travelling, you cannot use above way of charging especially when you are mobile or simply there is no AC power available, charging through a power bank is the best option.

how to charge phone using power bank

How Power Bank Works

A Power bank is simply energy storage like a battery. It has input and output ports. The input port serves as the connection to the charger while the output is where the devices use the power bank connect. In the case of a portable power bank, the input and output connectors are already USB compatible. Power bank stores energy when it is charged. This energy will serve as the power source to the device that uses the power bank.

how power bank works

Power Bank Construction and Circuit Block

It is not difficult to understand how power bank works. Further informations that may be relevant to you is the circuit block diagram of a power bank. A power bank has input port, charging circuit, battery, discharging circuit, output port and indicators.

The input port is use to charge the power bank. The charging circuit is designed to recharge the power bank from a charger. This regulates the voltage and current that will supply to the battery. The battery is the energy storage element. The discharging circuit is functioning almost the same to the charging circuit.
It will control the current drawn from the battery. Too large discharge current will shorten the battery life. Output port is use to connect to the devices and gadgets that will charge from the power bank. Indicators are simply added features for visual monitoring.

power bank block diagram

How many charge I can get from a power bank? How long a power bank charge last?

Look at your cell phone charger output current rating. See below as example.

charger current rating

Supposing the current rating is 2A and we will assume that your phone will draw all this current. Supposing the usual charging time 2 hours, if you have a power bank with a 10 ampere-hour rating, you can fully recharge your phone twice. Below is a simple calculation.

Power Bank rating = 10 ampere-hour

Current consumption = 2 amperes

Charging time = 2 hours

Number of charging = Power bank rating /(Current consumption X Charging time) = 10 / (2 X 2) = 2.5

Power Bank Selection Guide

1. Define your budget

If you have identified your budget, look for best item on that budget range. Best item means the highest energy capacity, has safety features, and has passed standards and so on.

2. Know your needs

Knowing your needs means you should set how many times you need to charge your phone or gadgets from the power bank in a day.

Supposing your phone is drawing 1 ampere of current and get fully charge in 2 hours, it has 2 ampere-hour energy consumption. If you want to charge from the power bank at least 3 times a day, then you must consider buying a power bank with an ampere-hour rating of more than 6 A-hr or 6000 mA-hr.

3. Consider the connection ports

You must ensure that your phone or gadget terminal connections are compatible to the power bank ports.

4. Size

Power banks come in different sizes. Select the best for you.

5. Safety

If you are looking for a high end and reliable power bank, then consider buying the one with a safety stickers and certificates like from UL or other safety bodies.


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.