Best Portable Charger - What is a power bank, what to look for when buying one.

What is a power bank aka a portable charger.

With smartphones getting more feature-rich every day, they become more and more indispensable companions of our everyday life. Regardless of the brand or operating system of our phone, we all have one thing in common: "Our batteries never hold enough power." No matter if you own an iPhone, a Samsung's Galaxy or any other phone, you probably can't get through a single day without recharging your phone and you wish you had a bigger battery. And if you are using a tablet on the go, when your battery shows the dreaded 20% you not only have to start looking for a power outlet, but as soon as you find one, you are "grounded". The good news is: You are not alone and there is a solution to this quite common problem. The solution is: a portable charger aka. a power bank. As its name suggests the device function is quite simple: Store power when available and provide a charge for your portable device when a wall or a car outlet is not available. In recent years, thanks to the power connector standardization, manufacturers were able to build relatively universal external portable power banks that can be used by most of our power hungry devices, besides smartphones and tablets they can be used by digital cameras, camcorders, portable speakers and many other device that can use a standard USB port as a power source. And they are not your old external emergency battery, the best power chargers can charge your phone as fast as wall chargers and sometimes even faster.

What parameters of the best portable charger are important and how to interpret them

Let's look at a list of portable charger's characteristics that you should evaluate when choosing your "best portable charger". Not all smartphones are the same but there are a few important characteristics that we need to consider when comparing portable power banks, regardless of the phone brand or its operating system. They are:
  • Power Bank Capacity
  • Output Port Amperage
  • Multi-port Configuration type
  • Power Bank Portability
  • Power Bank Durability
  • Storage Element Quality
  • Phone Connector Type(s)
  • Power Bank Smart Charge Port Circuitry
  • Power Bank's Extras (solar power recharge, weather resistance, etc.)
We will look at all of those characteristics and explain what to look for in the best portable charger, but when we are evaluating a power bank the very first question that we need to ask ourselves is: "How big a portable charger we can comfortably take with us, without making it a nuisance? If carrying our charger becomes a chore, we tend to leave it behind and just when we need a charger we are stranded without one.

Power Bank Capacity

One of the most important information about a portable charger is its capacity. Power bank's capacity describes its ability to store electrical charge that can be used for recharging our smartphone or other device. The capacity number indicates an amount of electricity that can be stored in our power bank. The portable charger's capacity is expressed in mAh (mili-Ampere-hour). For smartphone portable chargers this number would be in a rage of 3,000 mAh to about 25,000 mAh (for universal high capacity power banks for laptops and other high powered portable devices this number can be significantly higher). Before we can determine our portable charger's capacity needs, we should know our phone's internal battery capacity. To find this number you can either consult your phone's documentation or you can use one of the cell phone reference sites (e.g.GSM Arena). Once you know your smartphone battery's capacity you should limit the possible choices for your portable charger to ones that have capacity at least as big as your smartphone's and preferably double that number.

Output Port Amperage

In plain English amperage is an amount of electricity than can pass through an electrical circuit. It is measured in Amperes or Amps for short and the symbol is an A. In general, USB ports support (in a 5V charging mode) an amperage between a 0.5A and a 2.1A. A good portable charger should support at least 1A on every charging port, below that amperage it functions more as an external battery than a charger. If your device's power consumption is relatively high, charging it at 0.5A using your device, you might notice that despite your charger being connected, you still are hemorrhaging battery power, just a little slower. When you choose the best portable charger for your smartphone or your tablet, you should make sure that the charging port's amperage is at least 1A for smartphone and for charging tablets it should be rated at 2A. Modern power banks also feature special smart circuitry that protects your phone, in case it does not support charging at high amperage (we will look at smart charging circuitry later in this post).

Multi-port Configuration Type

Our next topic will closely relate to the amperage but applies only to the high capacity chargers. Larger chargers often are equipped with multiple charging outlets. With such a configuration we need to look at the configuration and the total charger output value. With split type circuitry the situation is simpler because each port is rated for a specific maximum amperage and it does not fluctuate. In case of a shared type circuitry, we need to consider a total output and the output rating of each port. If the total output equals to the sum of maximum output ratings of all ports, all ports will charge at the specified amperage rating. For example, a portable charger's total output is rated at 3A, it has two ports, one rated for maximum amperage of 1A and one rated for a maximum amperage of 2A. In such a case, each port rating is a true maximum output rate. Now if a charger's total output is rated at 2A, it will often have two ports rated one rated at 2A and one rated at 1A. In this scenario, the real output will depend on how many devices are connected to the charger. If two devices are connected, each of the devices will be using 1A of the shared total amperage of 2A. If only one device is connected, then the device will be using the maximum amperage depending on the connected port rating (2A or 1A). When evaluating multi-port portable power bank, if you see "amperage rating up to 2A", the chances are that the charger is using shared circuit configuration.

Power bank portability

When selecting the best portable charger for our phone we should consider a few important portability factors that will affect our choice. How am I going to carry my portable power bank? If you plan to carry your charger in your pocket or a purse, you should consider one that is small enough to not create discomfort. You might even consider getting two small ones instead of a bigger one. How many devices are expected to be charged with my charger? If you plan to charge your phone and a tablet, you should look for a bigger one with multiple USB charging ports. If you plan to travel with your family and access to power outlets is going to be limited you might consider getting a high capacity charger with multiple ports for all your devices. The interval between access to a power outlet will also play a role. In my experience you should start with a compact unit, some of them are not much larger than a lipstick, and as you get experience using it you will have a better idea about your power needs.

Power storage element quality and durability of your portable charger

All of top brands on a market use good quality batteries for their chargers, but because of the popularity of portable chargers, there are counterfeits being made. When you decide to buy your next portable charger please make sure that you are buying it from a reputable source, you can also search the Internet for instructions on how to spot a knock-off. Some manufactures posted pictures on their websites that could help you confirm that you got the genuine item. We no longer need to be concerned about so called Memory-Effect as current portable chargers use modern Lithium-Ion technology and they are not sensitive to a partial capacity charging and their capacity will not degrade due to an interrupted charging cycle. As far as durability is concerned, most manufacturers build their portable chargers strong enough to take the abuse of everyday use without endangering the charging element. For extreme conditions you should look for chargers that were specifically build for extreme conditions (e.g. SadoTech 10400 mAh Portable Charger). The charging element will eventually degrade and start loosing its ability to store power, but a good quality charger should last for about 500 charging cycles before the degradation starts to show. For most users even if they use their portable charger every day, they should expect at least 2 years of use before they need to replace the unit.

Connector types and compatible devices

Over the last few years most of our battery powered electronic devices standardized to use 5V USB port as a power source. The benefit of this standardization is an ability to use a single charger across an array of electronic devices that can draw power from a USB power port, that includes smartphones, iPhones, tablets, mp3 players, portable game consoles, digital cameras, camcorders and more. This is true as much for wall and car chargers as it is for the portable power banks. In most cases all you need is a right connector cable that can be plugged into your device. One word of caution: To avoid damage to your electronics, before you connect your device to any charger you should make sure that your device is compatible with the charger amperage or that your charger is using smart circuitry to regulate the power output (more about it in the next topic).

Smart charge port circuitry

Rechargeable batteries are not all the same as far as charging parameters are concerned. Each battery can have their own optimal incoming power parameters specification, sometimes also called a charging protocol. The level of compatibility between those optimal parameters and the actual power provided by a connected charger will affect the efficiency of the charging process and that in turn will determine the time required to fully charge the battery. Manufacturers of a specific battery or the device holding it, usually will provide you with a fully compatible charger either a wall socket type, a car socket type or both. The situation is quite different when you buy a universal power bank that had been designed to provide power to any device accepting 5V USB charging source. Some manufacturers install in their chargers a specialized circuitry that can detect the charging protocol required by the connected device and adjust the chargers output parameters to match the charging protocol of the recipient to optimize the charging process. When buying a portable power bank you should be able to tell by the device description if the selected unit employs a smart circuitry for charging optimization. If you are not sure you should be able to find that information on the manufacturer's website. Manufacturers invested time and effort into designing those dedicated power management modules and they do not want to go unnoticed.

Solar power

With recent advancements in solar power panel technology, more and more devices start to feature a solar panel options. Some manufacturers are starting to implement this alternative power source also in portable power bank designs. For people that frequently find themselves in a remote location, (e.g. hiking, skiing, mountain climbing or sailing, just to name a few) without an access to a permanent power source, a portable power bank with a solar panel could be a very attractive alternative as a power source for their cell phone. While the efficiency of solar panel technology improved significantly in recent years, don't expect your charger to recharge in a matter of minutes. The fastest time charging unit that we have seen is a brand new (not available for purchase yet) Helios by Solpro. It claims 4.5 h charging time in a direct sunlight, it achieves this remarkable result by employing an innovative design with two foldable side panels. If you are looking for solar powered portable power bank please check here (we are going to post new developments in portable charging technology at the end of this post) or search the internet for user reviews and or recent releases as the technology and and efficiency of solar panels improves nearly every month or so.

Extreme conditions specialized portable power banks

For people that frequent extreme conditions environment, portable power banks' manufacturers had create special design that can withstand much tougher handling then a regular everyday device. In many cases they created durable and strong protective outer shell to protect the charging components from shock and water. They are usually slightly more expensive but compensate with higher capacities. At the moment of this writing we found one unit that made the bestseller list on It is SadoTech 10400 mAh Dual USB Portable Charger featuring a tough, rugged outer shell and a high capacity charging unit, it is also a very good performer as far as the charging speed is concerned. There were other good units, some of them even combining solar power technology in their waterproof design. Because extreme conditions situations can have very unique requirements, our only advice is that you do research before you buy, or post a question in our comments section.

More Info

Portable Chargers FAQs
How To Extend Battery Life With Proper Charging
Five Common Portable Power Myths - Debunked by Mashable
Portable Charger News Updates

02/23/2015 - StoreDot - Smartphone users community once more electrified by a prospect of 30 second charge for their smartphones.

Smartphone users' #1 complaint: the phone battery's performance, might get a practical solution in a near future, CES Show followers probably have heard about this new incredible technology with roots in nanotech. The StoreDot company estimates that a commercial product based on their innovative storage solution might be ready for consumers as early as December of 2016.

StoreDot - 30 seconds smartphone battery charge - video demo.
Company Website: StoreDot
We love our smartphones and become increasingly dependent on them with new functionality added every day. The one aspect that frustrates nearly every smartphone owner is the need to charge them at least daily and sometimes more often depending on usage. How frustrated are we? Just run a simple search on Twitter for "phone battery" to see that there is at one tweet every minute with bad news regarding phone battery. It is a little wonder that phone and battery manufacturers are constantly looking for ways to extend the battery life or develop new ways to store energy. Just to ease our dependency on power outlets, there is a whole new product, a portable charger to provide us with power on a go. This time smartphone users seem to get excited with a news about a new technology that while not making our batteries last longer, promises to shorten the charging time for our batteries from current hours required to fully charge a typical battery to just a few minutes to get from 0% to 100%. The innovation is coming from an Israeli startup StoreDot that developed this nanotech technology and currently is working on perfecting various aspects of practical applications. That is the good news. The bad news is that the commercial application for this technology will not be available for consumers for nearly two more years according to the company estimate. Another bad news is that even after the technology is ready for consumer devices it cannot be retrofitted to work with our current devices and we would have to upgrade to a new model to get this amazing feature of instant charge. To read a full interview CES interview given by the company to BBC editors please visit: CES 2015: The charger that boosts battery in seconds

01/28/2015 - Solpro - Now Shipping Helios - The Fastest Recharging Solar Powered Portable Power Bank.

After completing their Kickstarter crowdfunding campaign (Solarpod), SolPro now shipping their Helios - foldable solar panel powered portable power bank.
HELIOS - A solar powered 5,000 mAh dual USB (1A; 2A) portable power bank
Company Website: Solpro
Back in September of 2014 SolPro completed their crowd funding campaign with an impressive result of $132,524, nearly a $100,000 over their initial goal. Now, after only about four months the company is starting to mass ship their final product. According to the company's website it is available from Amazon, Raukuten and NewEgg, priced around $120.00. Helios is a unique solar panel powered portable charger the features three solar panels thanks to a foldable wing design. This solution enables the charger to increase the total active solar panel surface and according to the manufacturer recharges the device's internal 5000 mAh battery in only 4.5h. For more info please visit Solpro website SolPro also manufacturers a single panel solar 2,800 mAh portable charger Gemini.

01/14/2015 - ZEROHOUR - Getting Ready To Launch New ZEROHOUR RELIC XR. A Tactical Flashlight With An Integrated Portable Charger.

After a successful presentation of their latest prototype at the annual CES Show, Zerohour sets up a Kickstarter crowdfunding campaign to bring their RELIC XR to market.

ZEROHOUR RELIC XR - A state of the art tactical flashlight with integrated dual port 3,400 mAh portable charger
Company Website: ZEROHOUR
After a very successful introduction of their new RELIC XR by ZEROHOUR at this year's CES Show, the company launched a crowd-fundraising campaign at Kickstarter to bring this product to market and to offer an early version to their supporters. ZEROHOUR RELIC XR is a state of the art tactical flashlight. Build with premium materials and a precision design and manufacturing. The extra twist to this flashlight is the fact that it provides a build in 3,400 mAh portable charger for your phone or other device. As of this writing the pricing has had not been available yet, but we can expect that its exceptional quality will come at a premium. For more information please visit the ZEROHOUR RELIC XR webpage.

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Q: What is a power bank?

A: A power bank term in a cell phone power context is reserved for a device that provides power for charging a portable device without a need of a connection to a power grid. In most cases it provides an electrical power storage and a DC power connection that will supply electrical current to a portable device. Current power banks at the minimum will provide a USB charging port that will enable a USB compatible portable device to charge without a need for wall power outlet.

Q: What is the best way to monitor Android battery?

A: For basic battery information you can use an Android build-in battery tool. For more detail information you can use some of the free Android apps like: Battery, GSam Battery Monitor or Battery. For enhanced options you can also buy: Battery+ or Battery Repair - the perfect doctor to boost your battery!

Q: How many charges can I get from a 10000mAh portable charger?

A: To calculate the total number of charges that can be provided by any portable charger we need to divide total effective charger capacity by a capacity of the device being charged. The total effective charger capacity in most cases can be calculated as a 90% of the total charger capacity, the remaining 10% is the amount of energy that unfortunately is converted to heat during a charging process. In our case of a 10000mAh portable charger the effective capacity is 9000mAh. Let's assume that we are charging a smartphone with battery that has a 3000mAh capacity. The number of full (0% to 100%) charges will be 9000mAh / 3mAh = 3.

Q: Is there a difference between a powerpak, a powerpack, a power bank, a powerbank and a portable charger?

A: The only difference is a spelling. All those terms usually refer to the same device, a portable battery charger. Some of the names like power bank and power pack had been created for marketing purposes while others like powerpak, powerpack and powerbank are probably creations of a social media, it is possible that they originated as #powerpack, #powerpak and #powerbank respectively. Having said that, the term powerpak can also refer to other things than portable charger, it is also a very popular gaming term and means a collection of tips, tricks, codes and other helpful items.

Q: What is the best portable charger for my phone?

A: There is not a single best portable charger. It always depends on your current needs. For your standard smartphone in most cases the best portable charger would give you at least one full charge and be portable enough to take it anywhere without being a burden. For a tablet on the other hand, the best portable charger will be one that would feature a high capacity 8000 mAh or more and has at least one port rated at 2A for faster charging.

Q: Can using my phone while charging damage my phone?

A: The short answer to this question is: NO. The few reported cases of phones exploding or caching fire are not related to the fact that they were used while charging. As with any electronic device there is a possibility of a faulty circuit or battery and occasionally they can catch fire or burst. In fact many of the reported events happened without charger being connected to the phone. Having said that, if you consider the number of smartphones in use and the number of them that caught fire or burst the chances of that happening to you are on a par with you getting struck by a lightening.

Q: Can my phone's battery explode?

A: As any electrical device our phones are capable of creating a high temperature and consequently ignite. In case of our battery in an extreme case it can even burst (the term explode is highly exaggerated). The technology used to make our smartphones and build quality reduces the danger of such an event to almost zero. Usually the cause of those rare cases of phone fires can be traced back to either a material defect or environmental factors like dust or moisture. When we consider that out of billions (yes billions) of cell phones ever produced only a handful of them had been reported to catch on fire or burst, chances of the happening to you or to somebody you know are very low.

Q: Can a portable charger damage my phone?

A: To answer this question we have to go back to the topic "Output Port Amperage" in the post above. Standard USB specifications limit the charging port amperage to 0.5A or 0.9A for USB v 2.0 and USB v 3.0 respectively, those ports are typically found in our desktop computers or laptops and they are safe for your phone. Unfortunately charging large capacity batteries (e.g. tablets) using 0.5A would take a really long time. To speed up the charging process manufacturers build chargers that output power at a much higher amperage (usually between 1A and 2.1A - for more info read the post above). The best charging results are achieved when the amperage rating of your phone charging port matches the output of your portable charger but unfortunately experience teaches us that finding the phone's charging port amperage rating is hard or impossible. To avoid a potential damage to your phone you should use portable charger with port amperage rating 1A or (and this is my preferred option) use a charger that features a smart circuitry that regulate the port amperage depending on the connected device requirements.

Q: Is there a "right" way to charge your smartphone battery?

A: Replacing your phone's battery can be expensive and in some cases might require a trip to a specialized service store. But don't despair, with a proper care your battery should last three to five years and you might not need to replace the battery, but rather get a new smartphone model instead. There are things that you can do to maximize the battery lifespan. Before we list ways to pamper your smartphone battery, I wanted to mention one more aspect of rechargeable battery technology. If you ever heard the term "memory effect", please try to forget that it ever existed. Modern Lithium-Ion based batteries do not suffer from the memory effect and charging them as their Ni base cousins is the worst thing that can happen to them. With that in mind let's begin.
  • Avoid Extremes
    Due to the Lithium-Ion battery chemistry, the optimal operating charge level for your smartphone battery is between 40% and 80% of the total capacity. In practice that means that you should rather charge a little at a time instead of letting your battery drain and than charge it to full capacity. In fact going from 100% to 0% and back to 100% is the worst thing that can happen to the battery. If that happens on a regular basis, your battery's lifespan can be severely shortened due to the degradation of the internal components. Please remember that a frequent charging is not harming your battery in any way and it is save to do it as often as you can, just try not to charge it to all the way a 100%. If you don't have access to a power source it might be good idea to use your portable charger throughout a day to keep the battery happy.
  • Don't Let It Stay At Zero
    For reasons related to the battery chemistry and its construction, the most damaging and dangerous situation is to let the battery to discharge completely and stay this way for a prolonged time. Lithium-Ion batteries left drained of electricity are susceptible to forming copper shunts that could cause partial or complete short. This could potentially destroy a battery or worse, create a dangerous situation next time we try to charge the battery.
  • Calibrate Your Battery Occasionally
    Internal battery microprocessor keeps a track of how much electricity can be stored in a battery and what is the current charge level, it uses that information to display the current battery level on your phone's screen and to manage the energy usage for your device (dim the screen, shut down services etc.). To help it to do this job better we need to occasionally perform a full charge cycle that would take the battery to 0% and back to a 100% for calibration. You should do that every 2-3 months and not more often than once a month.
  • Keep It Cool
    Because of the chemistry used for electricity storage, one of the worst enemies of your battery is heat. The optimal operating temperature for your battery is 59°F (15°C), this is hardly an optimal temperature for humans but a room temperature should not degrade your battery capacity at a catastrophic pace. What you want to avoid is leaving your phone in a direct sun on a hot day or leaving it in a car to bake. You might want to keep this information in mind for the next time you are going to pick a protective case for you smartphone, try to choose one that would allow to dissipate heat and keep your phone as cool as possible.
  • Avoid Wireless Charging
    While wireless charging is a very convenient way to "juice up" your smartphone with a minimal fuss, it is not doing any favors for your battery Wireless induction based charging technology inherently suffers from a major drawback of generating waste heat during the charging process. In turn the heat generated during this process will shorten your battery lifespan if performed on a regular basis. Because this is a very convenient way to charge your phone, don't feel bad if you use it occasionally, especially to just "top it off", but remember that staying on that charging mat shortens your battery lifespan.
  • Avoid Fast Charging
    Fast charging has a great appeal in our busy lives. There is however a downside to the fast charge because Lithium-Ion batteries prefer to be charged at a slow steady rate. If you are using an aftermarket charger (wall or portable), try to pick one that has a 1A port for your phone and features Smart Charge Port Circuitry. Use fast charging only if you are pressed for time.
To read more about rechargeable battery technology, chemistry and anything else that you might want to know please visit Batteries: The Absolute Definitive Guide

Q: Does the USB charging cable length matter?

A: The short answer is no, but that applies only to a good quality USB cable. Far more important than the USB charging cable length is its thickness or gauge. There is a lot of cheap USB cables on the market that use wires that are very thin. The gauge markings for those wires are 28/28 (data/charging wires). To ensure proper charging you should use cables that are marked as 28/24. Here are some trusted brands: USB Monoprice 3ft, Monoprice 6-Feet and for iPhone Belkin 10-PIN 24/28awg, StarTech USBLT1MBL Apple 8-pin Lightning and PortaPow Specialised 21AWG 5ft.
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