How Power Bank Works and Best Power Banks in India

Updated on 2017-12-09 by Tejas Upmanyu

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We are all in unison when we say that smartphones have superseded laptops and computers a long time ago to become our daily workhorses. Smartphones are the most important device, right in our pockets. Though these tiny devices have transcended their limitations of processing power and storage in an explosive manner, powering them deep down are still chemical-based batteries, which have seen advancements but not that staggering compared to other departments. Batteries are still a major limitation of these modern age processing beasts. And as it happens, an average smartphone today has a battery of around say ~3000 mAh, It lasts only about a day with normal use, heavy lifting like gaming and high-resolution videos can drain the battery very quickly, lasting only a few hours. That’s not all, the present chemical batteries have a definite lifespan, in most cases we see a constant decrease in capacity after 2 years of good use. Hence, the burning question, what’s to happen if your device gets low on battery on a full working day, just in the noon. Well, of cour, e you’d hop on to a wall charger but is that it? Is that the way, homo sapiens - ‘ Man the wise’ have made advancements in the sole thing that powers the devices they adore. Well, there’s a way to cut the loop and that’s called ‘Power Bank’.

What is a Power Bank?

In simple terms, a Power Bank is a rechargeable, high-capacity battery, wrapped around in a sophisticated enclosure with ports to universal ports such as USB-A to charge all the small battery-based devices, like smartphones, smartwatches, tablets, wireless headphones and so on. So that you whenever any of your personal devices is low on battery, you can just plug it in your ‘Power Bank’ and It’ll charge just like it would with a wall charger. The first question, you’d ask here is, “Ah, well genius? Isn’t carrying a whole battery just the point behind putting them in smartphones, what about portability?”, and I’d say, “Yes, you are perfectly right, but Power Banks are not big batteries, with tons of weight. These are high capacity batteries packed in small enclosures just about the size of a smartphone or close to it. How’s that for portability’s sake.” Power Banks are portable as they are just the size of a smartphone and they pack much power to charge a device over multiple times depending on the capacity of a Power Bank. Sure, it isn’t the one true solution to the battery limitations but its a welcome solace. 

Power banks have become a lot more just an accessory to a major weapon in your personal device armoury. Now, that we’ve got our introduction to Power Banks, let’s delve into some details.

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How does a Power Bank work?

As it occurs, Power Banks are just sophisticatedly wrapped, high capacity, rechargeable, portable batteries, with a few ports where you can connect your device with to charge.  Being just batteries at the end of it all, Power Banks need to be charged sometime too, so that they can share the juice down the road whenever one of your devices is low on it. 

What are the different kinds of Power Banks?

Power Banks occur in a variety of flavours depending on the base technology on which they are based, chiefly Power banks can be of following types - 

• Solar chargers

• Phone case chargers

The ‘Solar Chargers’ are the type of Power Banks which replenish their battery via the almighty solar power. They have a layer of solar chargers on their body, which constantly harnesses energy from the sun, given it's in sunlight. The photo-energy from the sun is converted to electrical energy, all thanks to the solar cells. These solar cells then store the energy which powers your devices in the end. It's that simple, the only downside being, who is going to sit under the sun all day to charge it? Given the surface area of power banks, solar charging is also an extremely slow process.

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The ‘Phone Case’ type of power banks are common batteries packed with the smartphone case itself so that you don’t need to carry the power bank differently, Its just wrapped around your smartphone as a case and whenever you need it, Its just sitting right there to charge your device. The catch with these type of power banks is that, due to that visible bump caused by the battery, It looks certainly awkward and feels quite wobbly in the hand, like a mobile device from the 90s. These type of power banks are also not very versatile as they can only be used with smartphones and not all smartphones are fortunate enough to have a smartphone case made for them.

• Laptop chargers

• Phones/tablet chargers

This classification is based on the powering capacity of the power bank, If it has a large solid battery inside it with good potential, enough to power a laptop, then its a laptop power bank, else Its a phone/tablet power bank. Though it's worth mentioning that, it's not the case that laptop power bank won’t be able to charge your phone, of course, it will be given it has the lower rating output port suitable for your phone battery. The same cannot be said for phone/tablet power banks. 

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How to charge a Power Bank and how long does it take?

Modern age power banks come with USB-A input port which can be used alongside a common high rating charger to charge a power bank. Just get a USB-A cable, insert it into the Power Bank’s input port, connect the other end to a wall charger (possibly with a higher rating, to make the charging faster) and turn on the switch, wait for a few hours, and voila! You just charged your power bank, which can be used to power other smaller devices whenever the need comes be.

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If your power bank is a solar-charged one as mentioned above, Just keep it under the sunlight for a few hours and It’ll charge just fine, after that you can use it just like you would use an ordinary power bank. 

As for the ‘few hours’ part, It can be a long ‘few hours’ or really a few hours depending on the charger you use to charge your power bank and the battery capacity of the power bank. If your power bank has a bigger battery, It’ll obviously take a longer time to charge. The charger used also has a major play, if you use a ‘fast-charger’ It’ll take lesser time and if you don’t well It’ll take more. 

For reference, a small 1500 mAh power bank will take just about 2 hours to charge, while a bigger 10000 mAh one might take up to 8 hours to charge. 

Some Power Banks don't work well with high-capacity chargers (like the ones that come with iPads). Trying to fast-charge a Power Bank from a 2A charger can result in damage to the internal circuitry, which isn't covered by warranty.

How many times can a Power Bank charge a device?

This question also has a variable answer, It all boils down to the capacity of the power bank you are using and the capacity of the device(s) you are going to charge with it. The capacity of a battery is measured in mAh (milliAmpere hour). The higher the mAh rating, the higher the capacity. The higher the capacity of a battery, the more It’ll last on a single charge. Always look out for mAh rating of the power bank you are buying, It should be preferably considerably more than the mAh rating of the device you are going to charge with it. 

For example, the Google Pixel 2 has a 2700 mAh battery, If you use a 10000 mAh power bank, you can charge the device roughly 3-4 times. As you may think, Its not a zero-sum game, the mAh rating is not the perfect standard and there are a lot of technical factors that make the capacity, actually less. It may account to standby charge leak in batteries, or efficiency of the power cord or the battery percentage of the smartphone at which it is plugged and a lot more.

In general, the following values can be considered safe.

Power Bank Rating

Mobile Phone



Approx. 1 full charge

Approx. 25%


Approx. 2 full charges

Approx. 50%


4 full charges

At least 100% full charge

If you are into some super cool mathematics, this formula gives you the exact times a power bank would be able to charge your device. 

(Power Bank Rating (mAh) × Efficiency × Device Depletion)  / Device Capacity (mAh)


What’s the different types of batteries in a Power Bank?

Nowadays, Batteries are mostly based on two types: the ‘Li-ion’ and the ‘Li-Po’. The ‘Li-ion’ stands for ‘Lithium Ion’ and use a variety of cathodes and electrolytes. Usually, Its a Lithium (Li) based Anode dissolved in carbon or graphite and a cathode of lithium cobalt oxide (LiCoO2) or lithium manganese-oxide (LiMn2O4) in an liquid electrolyte of lithium salt. As they use a liquid-based electrolyte, Li-ion batteries are limited to shape and size. They are usually in prismatic/ cylindrical form.  Li-ion batteries are common, cheaper and possess high energy density but have significant loss of capacity as they age. 

Lithium-ion-Polymer (Li-Po) is the next stage of Li-ion batteries which mitigate the issues by using a polymer-based (plastic) electrolyte, allowing batteries to be made in a variety of shapes and sizes. Li-Po batteries don’t show significant ageing effects as Li-ion so are a better choice. With betterment comes more costs, hence Li-Po batteries are costly compared to Li-ion.

What’s the life-span of a Power Bank?

This is a bit heavy question and requires intricate details. The two factors that play a major role in deciding the life of a power bank are -

  1. The number of charge/discharge cycles performed.
  2. Charge retaining capacity.

The details vary from power bank to power bank but It all depends on the manufacturing, quality of components, the technology used etc. Power banks operate on the theme of ‘cycles’ a cycle is stated as charging from 0%-100% and depleting back to 0%. The cycle need not be continuous, It can be discreet. If your power bank is a quality one, It’ll have at least 400-500 cycles of capacity. That allows it to last easily for 1.5 years being used daily. After that, It’ll start losing it capacity at a rate that again depends on the quality and manufacturing of the power bank. 

The charge retaining capacity is described as the time, a battery will hold the charge once charged to full on no usage. This also depends on the quality, circuitry and technology of power bank. Normal power banks have a retaining capacity of around 3-4 months, while cheaper ones may not last even a few weeks.  

The environment in which a power bank is kept in also plays a major role, In colder temperatures, power banks tend to retain the charge for longer durations while in too hot temperature their charge evaporates faster and decreases lifetime. 

Also Its a no-brainer, being a battery packed device, power banks must be kept far away from liquids, as not only liquids can damage the power bank they can also cause certain chemical reactions that might lead to exploding of the power bank battery. BEWARE!


How to choose a right Power Bank?

Well, “Which power bank should I buy?” is the ultimate question. And here are some insights into how to choose a right power bank for your needs. 

Let’s proceed towards this algorithmically, 

Q1. List down how many devices you would be charging with the power bank.

Q2. What’s the power rating and battery capacity of each of these devices you listed?

Q3. What’s the highest battery capacity you need to charge in your devices?

Q4. What’s the most common rating (Voltage, Current) your devices require for charging?


Answered all these questions? Alright, so the key to choosing the right power bank depends on the answer to these questions. Mostly we charge 2-3 devices with a power bank, In my case 2 smartphones and a smartwatch. The highest battery capacity I need to charge is 3340 mAh. The rating of devices is different, one charge on 5V, 2A and other on 5V, 1A. So, select a power bank in your appropriate budget which has the battery capacity at least greater than the largest capacity device you have. If you need to charge different rating devices, see that the power bank you are choosing has multiple power outputs. Look out for an efficiency rating of the power bank, It should be as high as possible. Further, see if the power bank has compatibility with fast chargers and of course additional features such as battery indicators, charging indicators LEDs, as well as build quality, are among secondary features you should consider while buying a power bank. 

Best Power Banks in India

Don’t sweat it out, It's not magic and we’ve got you covered. Here are some good power banks according to capacity and budget, find the one that suits you. Cheers!

Our favorite of the list is the Mi Power bank.

Intex Power Bank - PB11K - 11000mAH  - Rs 699

Syska Power Bank - Power Boost 100 - 10000mAH - Rs 699

Lenovo Power Bank - PA13000 - 13000mAH - Rs 1397

MI Power Bank - PLM02ZM - 10000mAH - Rs 1199

Intex Power Bank - IT-PB-4K - 4000mAH -  Rs 499

* Li-Po Based Power Banks - 

Lenovo Power Bank - MP1060 - 10000mAH - Rs 999

Philips Power Bank - DLP10006 - 10000mAH - Rs 2804



SuggestPhone’s Wrap Up: Power Banks -> What, Why and How?

So this was it! Hope you got to know all about Power Banks, What are they? and How Power banks work. In the end, we also shortlisted some great deals on power banks for you. Since their announcement at CES 2001, power banks have come a long way to become a common accessory for most of our smartphones. Given the high grade of power modern devices pack, an extra battery pack doesn’t hurt even if you have a big battery (believe me It's not that big) and for others Its a necessity. The Power Banks we discussed play well with almost any USB-charged device, Be it Cameras, Portable speakers, MP3 players, smartphones, tablets and even some laptops. It all depends on the capacity of the power bank you have. Power banks don’t bring anything new to the table, they are just a fine example of how existing tech can support us in our daily problems. They don’t overcome the battery limitations of the smartphones but certainly, help us in the process. Until scientists and researchers develop some life-changing battery technology for electronic devices, we are stuck with power banks. 

Here’s something to bring awe to your beautiful faces. 

“Samsung’s graphene battery will charge smartphones five times faster than traditional technology”

We sincerely hope for some solid developments in the battery department by tech giants like Samsung and others. Until then, keep close our ‘Power Banks’ article.What do you think of Power Banks and current battery technology? Do tell us on Facebook and make sure to follow us on Twitter for quality technical articles. Also, we are all ears to answer your questions regarding smartphones and technology. 

Until then, May the Power Bank be with you!

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