My Experiences Sharing: Buying a 20000mAh Power Bank

Power banks are the result of the collective efforts of many engineers and scientists in the field of portable power technology. The earliest form of a portable battery pack was the nickel-cadmium battery invented in the early 20th century, but the first commercially available power bank was introduced by Pisen Electronics in 2005. Since then, many companies have been manufacturing and improving power bank technology, making them more compact, efficient, and affordable.

A power bank is a portable battery charger that allows you to charge electronic devices on the go. It works by storing electrical energy in its internal battery, which can then be used to charge devices via a USB cable. Power banks come in various sizes and capacities, ranging from small ones that fit in your pocket to larger ones that can charge multiple devices multiple times. They are a convenient and useful accessory for people who are frequently on the go or need to stay connected but do not have access to a power outlet.

The capacity of a power bank is usually measured in milliampere-hours (mAh). To calculate the capacity, check the power bank's specifications and label to find the rated voltage and capacity. Multiply the rated capacity (in mAh) by the rated voltage (in volts) to get the watt-hours (Wh). However, the actual capacity may be less than the rated capacity due to energy losses during charging and discharging. The actual amount of power a power bank can deliver to a device may also depend on factors such as the charging cable, the charging speed, and the efficiency of the charging circuitry in both the power bank and the device being charged.

Lithium-ion and lithium-polymer batteries are commonly used in power banks, and each has its advantages and disadvantages. Lithium-ion batteries are known for their high energy density and long cycle life, but they can be more prone to overheating and swelling, which can be a safety concern. However, they can be made in a wide range of shapes and sizes, making them ideal for use in devices with unusual shapes or tight spaces. They have a slightly lower energy density than lithium-ion batteries, which means they may be slightly less efficient in terms of the amount of power they can store in a given space. The choice may depend on factors such as cost, performance, and safety considerations. It is important to choose a reputable brand and ensure that the power bank has been tested and certified for safety.

The number of times a power bank with 20,000mAh can charge a cell phone with a 4,000mAh battery will depend on several factors, such as the efficiency of the power bank and the charging circuitry of the phone. A rough estimate is to divide the power bank's capacity by the phone's battery capacity and then subtract some amount to account for energy losses during charging. 

So, in this case:

20,000mAh power bank / 4,000mAh phone battery = 5 charges (without accounting for energy losses)

Accounting for energy losses, you might get around 3-4 full charges, depending on the efficiency of the power bank.

It's important to note that this is just an estimate, and the actual number of charges you get from a power bank will depend on various factors. Additionally, some devices may have larger batteries or higher power requirements, which would affect the number of charges you can get from a power bank.

ABOUT THIS ITEM

Redmi Power Bank is a 20000mAh Li-Polymer battery with 18W Fast Charging.

It supports 5.1V/2.4A, 9V/ 2A MAX and 12V/1.5A MAX charging outputs.

It has dual input ports (Micro-USB/USB-C) and Dual USB Output with smart charging.

Ergonomics at its best, it is crafted using quality material and comes in classic black and white color.

It has 12 layers Circuit Protection, two-way Quick Charge, universal compatibility, easy to carry, and 6 months warranty.

It is made in India and passed through stringent quality tests and checks.

I purchased the Redmi, 20000mAh battery on September 09, 2020, and it's still working fine. Below, I am sharing the link to the Redmi power bank.

Redmi 20000mAh Power Bank: https://amzn.to/3JGBBv5