What A Power Bank (External Battery Charger) Is

Power Banks (External Battery Charger) are all the rage today, with the burgeoning use of smart phones and digital devices. In another article titled “How to Extend the Life and Performance of a Power Bank“, we discussed how you can optimize the use of your power bank.  But you might wonder how best to acquire a power bank in the first place.  Are there nuances to consider? Are there different types to look at? Should you care? The answer to all of these is a resounding YES.  Wonder why?  Well, read on ..

External Battery Charger

Power Banks are in simple terms external battery chargers.  They store charge and with in-built circuitry, control the flow of charge from the device to your smart phone, thereby allowing your smart phone to charge up in place of an AC outlet charge.  This is particularly useful when you're out and about on travel and do not always have the ability to charge via an AC outlet.  Think of all the scenarios where this is common – while you're on the road, in the air, or at the beach!  You surely do not want your smart phone to run out of battery in that critical moment when you need it most and can't find a way to charge using regular power.

The power banks for smart phones are portable.  They all mostly weigh a few ounces, so it's typically easy to carry them around.  Needless to say, power banks come in a variety of shapes and sizes, but in general, most are portable.  So that's not particularly a cause for concern, one device to another.  Most power banks also have a USB output, so that makes it really convenient.

A typical question that often arises is if a power bank can charge other types of digital devices, outside of a smart phone.  Think tablets, gopro, notebooks, ipads, camera etc.  In theory, the answer is yes.  But there's more to it than that.

Power in the Device

As with any circuitry, the voltage and the amperage (current) determine the power in the device.  As an example, if your device is capable of 5V and 1A current, it has a 5W power.  If instead, the power bank has the ability for 2A current, the power of the device doubles.  However, if your power bank has 1 output, say at 5W, then the ability to charge is restricted to one device at the rate of 5W.  And if however, your power bank has 2 outputs, one at 5V, 2A and another at 5V, 1A, you now have the ability to simultaneously charge two devices, and since one is 2A, you could charge a higher powered device such as an iPad more easily and faster, as compared to just a smart phone.

Power Bank Battery

Amount of energy in a device directly depends on the batteries used in the power bank.  There are typically two types of batteries you'll find in most power banks.  One is Lithium Ion and other is Lithium Polymer.  Lithium Ion battery is fatter and larger, while Lithium Polymer is thinner and flatter.  Power Banks with Li Polymer battery is hence thinner and flatter as well and might make it easier to carry around.  Li Polymer battery is also superior in that they don't carry a memory effect, so some of the factors we outlined in “How to Extend the Life and Performance of a Power Bank” are less serious in such devices.

The number of battery cells in the power bank determines how much energy can be stored in the power bank.  These typically range from 2600 mAh to 20,000+ mAh.  A 2600 mAh device (typically 1 battery cell) is sufficient for one full charge and discharge cycle of an iPhone device.  For more advanced devices, including such ones as iPhone Plus, you'll typically get 1/2 a charge of the smart phone, which is still sufficient to get going in an emergency state.  Needless to say, you'll pay far less for a lower energy power bank than a higher energy one.


Most good quality power banks have sophisticated circuitry in-built so as to prevent excessive charge/discharge or the power bank, as well as auto shut off to protect your digital devices during charge cycles.  Be on the look out for the specifications to ensure that your power bank device has voltage and current spike protections, so you aren't worrying about over charge or over discharges. These are important, and hence are reasons why you should care what power bank you acquire.

Pin It on Pinterest

Share This