How many times have you suffered from the discharge of a smartphone at the most inopportune moment? And if you need to urgently call or wait for an important message? Well, if there is a socket or computer nearby, from which you can quickly charge the device. But what if they are not? Exit - use an external battery (power bank). The Internet project “Be Mobile” has collected tips that will help you choose the best option for you.
To begin with, we will define what an external battery is and what are its advantages. An external battery or Power Bank is a portable large-capacity lithium-ion battery from which you can charge a variety of mobile devices: phones, smartphones, tablets or e-books. This battery is able to store energy for a long time inside. You can take it with you to work, study, on a business trip, or while traveling.
A portable charger can be made in various form factors with a plastic, polycarbonate or metal housing. On sale you can find models in the form of boxes, bars, discs, cones and tubes of various colors.
Power Bank is charged from the electrical network or from any device with USB-output (for example, a computer or laptop).
All external batteries are equipped with one or more USB ports. Modern phones, smartphones or tablets can be charged via the USB cable, which in most cases is included in the box.
id \u003d "sub0"\u003eThe main parameter when choosing an external battery is power consumption. Everything is simple and clear. The larger the capacity, the more energy the device stores, and the more expensive it is. Capacity is measured in mAh - milliampere hours.
On sale now you can find portable charging with a capacity of several hundred milliampere hours to several tens of thousands. Estimate the level of charge that you need, based on the capacity of the battery of your smartphone or tablet.
For example, in an average smartphone, the battery has a capacity of 2,000 mAh, in productive and expensive models - from 2,500 to 3,000 mAh. So a fully charged external battery of 5000 mAh is enough for 2-2.5 charging cycles. A fully charged external battery of 10,000 mAh is enough for 4-5 cycles. If portable charging is necessary for the tablet, then it is worth choosing from models of larger capacity, for example, 20 or 30 thousand mAh.
Lithium-ion or lithium-polymer batteries are installed in current portable power supplies. Depending on the type and design, the nominal voltage at the output of the battery may be different (3.7; 4.2 or 7.4 V), while the standard USB bus voltage is 5 V DC. Obviously, in this case, the battery capacity of 2000 mAh with a nominal voltage of 3.7 V even in ideal conditions will not work even one and a half hours when powering an external load connected via USB bus and consuming 1 A. In addition, the amount of electricity that can be stored batteries with the same capacity but different voltages will vary.
Tip 2: look at the current strength, it affects the charging speed
id \u003d "sub1"\u003eAnother factor that affects the charging rate is the current strength. The more amps, the faster the charging speed. For phones and smartphones, this figure should not be below 1 amp level. Otherwise, the process itself will be extremely slow. It takes 3 or 4 times longer to fully charge than it does from the mains.
For tablets, devices with a current strength of 3 A will be preferable. The ideal option is 4 A.
Tip 3: trust, but verify, because the declared capacity does not always coincide with the real
id \u003d "sub2"\u003eAnother important point is the real capacity of Power Bank. The fact is that many manufacturers embellish the performance of their products. Of the 50 models of portable chargers that came to us for testing over the past year, 46 had a capacity significantly less than what was stated. On average, the difference was 25%.
For example, the manufacturer indicated that the external battery has a capacity of 10,000 mAh, but in reality - 7,800 mAh. The difference is connected both with the developers' bad faith and improper storage of the batteries at the stage of transportation and subsequent sale.
The real capacity is also affected by such an indicator as self-discharge.
On average, external batteries with a full charge for two weeks are discharged by 5%. It is worth considering if you do not use Power Bank for a long time. To activate the electrolytic reactions before using it is worth putting the device on recharging.
Take into account the fact that over time the battery capacity will decrease. Our measurements show that during active operation a high-quality battery loses its capacity by 15% per year, the cheapest models - 35%.
To control the level of charge in almost all Power Bank LEDs are used. And some external batteries are equipped with LED displays that show the exact state of charge in percent.
Tip 5: Choose a power bank with multiple USB ports to simultaneously charge friends' smartphones
id \u003d "sub4"\u003eSome models of portable charging have several USB ports for connecting two, three or even more mobile devices at once. This option is suitable for simultaneous charging, for example, when you go on a trip with friends. It's comfortable. All of you can charge your phones, smartphones and even tablets.
Often you ask us where you can buy guaranteed high-quality external battery cheap. We can not give a definite answer. Of course, the reliability of purchase in a large Russian online store or in a retail network is higher, but prices there are higher. It is worth remembering that the little-known Chinese sellers have a feature: they can be fooled. Their external batteries are much cheaper than branded counterparts, they often indicate a volume of 2 or 3 times higher than real. Too low a price can be a trap. Although branded Power Bank in such stores can be fakes.
Compact
id \u003d "sub5"\u003eIf compactness is needed, you can pay attention to ergonomic models, for example, Anker Astro E1. This battery does not take up much space in your bag or pocket.
Universal
id \u003d "sub6"\u003eThe ideal option would be batteries with a capacity of about 10,000 mAh. This is about three times more than the battery in a modern smartphone, which means that even taking into account the loss of energy when recharging, it will be enough to fully restore the charge of the gadget several times. A quality example of such a power bank is the Anker PowerCore 10400 mAh model.
Another option for high-quality external battery with universal functionality - and Aukey PB-N42 10000 mAh.
Supports fast and wireless charging
id \u003d "sub7"\u003eIf universal options are not your option, then you should pay attention to models with additional features. For example, a power bank with fast charging support will be able to charge compatible gadgets much faster than usual. If the battery is capable of delivering a consistently high current (about 2A), then even without the support of fast charging, your gadgets will be charged stably and relatively quickly.
Among those recommended by us is an external battery Baseus Wireless Charge Power Bank of 8000 mAh. Its main feature is the availability of wireless charging standard Qi. That is, to charge the smartphone - no need to connect the wire to it, just put it on an external battery and that's it. Charging went. In addition to wireless charging with a current of 1A, the device supports a wired USB connection of two compatible devices, while the output current to the USB connectors is 2A.
A good option for iPhone is the Zikko PowerBag 6000 mAh external battery. The main difference from the popular Xiaomi external batteries is the MFI certification, that is, the battery is compatible with all Apple devices. The device supports fast charging - the output current to the USB-connectors is 2.4 A. In order to monitor the battery capacity - there are special LED-indicators on the end. A nice bonus - the smartphone connects to the battery via the included Lightning-cable.
With record capacity
id \u003d "sub8"\u003eIf you need a strategic supply of energy, pay attention to the external battery HyperJuice AC Battery Pack 26 000 mAh. With this giant you can quickly charge absolutely any device, including a tablet, other portable equipment and even a laptop. There are 2 output USB connectors. One provides the maximum power of a charge of 3A at a voltage of 5W, and the other, a current of 2.4 A. A pleasant bonus is the possibility of providing 220W of power to any electrical devices with power consumption up to 100W. You can connect a laptop, a flashlight and even a blender to this battery.
Housing HyperJuice AC Battery Pack is made of aluminum alloy, which perfectly protects the device from external mechanical influences.
We hope that our advice will help you buy a really high-quality external battery and without any problems charge your phone, smartphone, laptop or e-book.
In our top, only the best banks that can charge all your gadgets away from the outlet. 10,000 mAh - the optimal battery capacity, which is enough to recharge several devices, but which power bank to choose? This will help you our current rating.
1st place: Xiaomi Mi Power Bank 2 10000
The leader of our rating becomes legendary Xiaomi Mi Power Bank 2 with a capacity of 10,000 mAh. The device is equipped with a lithium-polymer battery and supports the Qualcomm Quick Charge 2.0 fast charging function with a maximum current of 2.4 A. It will take about 4 hours to replenish the energy reserves of this battery.
The connectors on the battery are standard - USB and micro USB, and in the scope of supply there is a corresponding adapter. Despite the fact that the case of Xiaomi Mi Power Bank 2 is made of metal, and the capacity of the bank is quite impressive, its weight is only 228 grams. This lightweight accessory can be worn even in a handbag.
Fans of bright gadgets will enjoy the large selection of colors offered by the manufacturer. And if this is not enough, you can “dress up” your external battery in a branded silicone case from.
Power Bank 2 can have a capacity of 20,000 mAh. This model is equipped with two USB ports and supports Qualcomm Quick Charge 3.0. The “big” crib bank is 100 grams heavier, although its case is made of plastic.
2 place: Xiaomi Mi Power Bank Pro 10000
Xiaomi, oddly enough, has become the absolute leader of our top. So in second place was one of the models of a popular manufacturer - Xiaomi Mi Power Bank Pro with a capacity of 10,000 mAh.
As well as the leader of the rating, this poverbank is equipped with a lithium-polymer battery and supports the Quick Charge 2.0 fast charging function with an output current up to 2A. Thanks to Quick Charge, the bank charges from 0 to 100% in just 3 and a half hours.
The main difference between Pro-charging and simple is the presence of a USB Type-C connector and an adapter for USB-C in the package. The rest of Power Bank Pro and Power Bank 2 are very similar.
3rd place: ASUS ZenPower 10050 mAh ABTU005
Breaking through the inaccessible wall of Xiaomi gadgets, ASUS ZenPower found the way to the third place of our top. This power bank is equipped with a lithium-ion battery with a capacity of 10,050 mAh and standard USB / micro USB connectors. The fast charge function is not here, and it takes about 8 hours to replenish battery life.
ASUS ZenPower is very (215 grams) and small. Power bank with dimensions of 59 × 90.5 × 22 mm can even be carried in your pocket, while the soft edges of the case will not exactly scratch your smartphone. As with Xiaomi, Asus offers a large selection of colors for its power bank.
4th place: Canyon CNE-CPB156
The fourth place of our top big banks was taken by a powerful and strict device - Canyon CNE-CPB156. From a battery with a capacity of 15 600 mAh, you can charge two gadgets at once, while the individual USB ports have different output currents - 1 and 2A, respectively.
Due to the lack of Quick Charge, this model will need to be charged for at least 10 hours, but then you will not have to worry that you will be left without power at the most inopportune moment. And also the small lamp is built in the powerbank - it is not enough, for what it can be useful.
As for the design, this is not a colorful Xiaomi - you will have to choose from only three standard colors. And even this compact one is very far from the compact Asus - Canyon weighs almost half a kilo and cannot boast of its huge dimensions of 111x225x36 mm.
5th place: Canyon CNE-CPB130
In the fifth place of our rating was the cheapest, but not the smallest external Canyon CNE-CPB130. In general, it is very similar to the previous model - here, too, there are two USB with a current of 1 and 2A for recharging your gadgets and a built-in flashlight. The capacity of the CNE-CPB130 is slightly less - 13,000 mAh - and it takes only 6 hours to fully charge the bank.
Here the manufacturer did not limit himself to a boring gray-white-black palette. Canyon CNE-CPB130 can be found in an unusual flower color - perhaps for some people this particular feature will be decisive when choosing a bank.
With a weight of 380 grams and dimensions of 111x203x36 mm, this “jar” cannot be called neither large nor small. However, Xiaomi gadgets offer the same features in a more compact package.
Which poverbank to choose depends on the number of gadgets that you will charge, on the speed you need to recharge the battery itself and the conditions in which you will use it. To carry the bank with you, you need a lightweight model like Xiaomi or Asus, and on long trips a voluminous power bank from Canyon is useful.
What unites all smartphones and tablets, no matter how modern and advanced they are? This weak point is always insufficient battery life and the ability to discharge at the most inappropriate moment. Even the prudence of some users and the obsession to always leave the house with a 100% battery charge cannot cope with this “Achilles heel”. An unforeseen situation, a delay at work or on the road - and you remain cut off from the whole world, and an external portable battery could save the situation. There are thousands of them on the modern market: from frank junk to very serious and reliable devices. Let's try to figure out how to choose an external battery that would meet the stated specifications and fully meet your needs. Bonus - the best power bank in 2017, presented in the domestic market.
What is a power bank: a small educational program
Power bankIt is an external battery, it is also a portable or additional battery., Is a small portable battery with which you can charge a number of gadgets: smartphones, tablets, cameras, e-booksand others that can receive power through a USB cable. The battery itself must be periodically charged from an outlet or a computer, it saves accumulated energy for a long period, so the paver bank can be easily taken with you to work or school, on a journey, and even to the end of the world - it will save when access to the outlet and for some reason there is no electricity in it.
Inside the power bank is located several batteriesconnected to the controller board. The board also houses a connector or connectors for connecting gadgets. Compatibility with a number of mobile devices is achieved through the use of a universal USB 2.0 connector.
An external battery can be of any color, shape and size - here the manufacturers please us and offer a lot of different options, so that it is both functional and pleasing to the eye. The body can be made of plastic, polycarbonate or metal: in terms of practicality, all the options are almost the same, but the metal case will make the battery somewhat heavier.
The higher the battery capacity, the greater the weight - do not buy on the model, the characteristics of which claimed 20 000 mAh, and the weight - about 100 g. If you plan to use your smartphone while it is charging from the battery, then it is better to choose the most ergonomic and convenient battery. If an external battery is needed only in order to reach a normal charge, then you can choose a compact model with a low weight. Some of them are even being implemented. in keyfob format.
It is appropriate to mention the existence battery covers. In fact, this is the same external battery, and its functions are the same, but its essential minus is sharpness for a specific smartphone model, and there is little practicality in this solution, so you cannot charge other gadgets.
Battery type in external battery: Li-pol and Li-ion
Often, customers who are wondering how to choose an external battery completely ignore the type of battery used, being distracted by other characteristics. The durability of the device and its functionality depend on the parameters of the batteries used.
In modern power banks are used two fundamentally different types of batteries:
Battery capacity is the most important indicator
The first thing that all those who are going to buy an external battery look at is its capacity. This is the most important characteristic of the battery, which tells you how many times and what kind of equipment can be recharged by it. You should not chase at record high rates - first you need to decide on usage scenarios:
There is no point in taking a battery with a capacity of less than 4000-5000 mAh - there will not be much savings in terms of price.
Manufacturers sometimes love somewhat exaggerate the actual battery capacity. Often, this sin Chinese companies without a big name. There are egregious cases when a battery with a declared capacity of 58,000 mAh is supplied in a lightweight case (and this happens, see photo below). If you buy an external battery in the store, you can take with you USB- battery capacity testerto check the stated numbers. It is worth such a tester in Chinese online stores 2-3 dollars. 
Important! Remember that the manufacturer reports the battery capacity, taking into account the voltage of the built-in batteries of 3.7 V. When the gadget is connected, the energy is transmitted with a voltage of 5 V, and then converted again for supply to the smartphone already with a voltage of 3.7-4.2 V. Due to the double conversion of the energy is lost, and sometimes losses can reach 20-30%. Therefore, do not be discouraged if a 10,000 mAh battery can charge a tablet with a similar capacity of only 70-80% - while this is the norm and technology costs.
Current strength is the second important indicator.
If you do not go into details and technical issues, the higher the current strength, the faster the gadget will charge from a portable battery. When choosing an external battery, be sure to check with what current can charge your smartphone or tablet, so as not to harm the gadget. Information must be indicated on the complete charger.
There are models smartphones with charge controllerwhich limits current strength. For example, the Sony Xperia Z3 controller has a limit of 1.5 A, and if you connect it to a battery with a port of 3 A, then the current will be limited, and the smartphone will still get its 1.5 A - these are the security measures provided by the manufacturer.
You can also find commercially available portable batteries that support the function. fast charge When using it, the voltage rises and the amperage decreases, due to which it is possible to fill in 30-40 minutes, on average, about 50-60% of the smartphone's battery (exact data depends on the parameters of the paver bank and the gadget itself).
Improper transportation and storage conditions of a battery can say negatively on its actual capacity.
Number of ports
From an external battery with several outputs and a small capacity, there will be absolutely no sense for obvious reasons, so there is no point in paying attention to such models. If the bank has several ports, then they can be used normally if the capacity is at least 10,000 mAh.
Another nuance. Different ports, in theory, are designed to simultaneously charge the smartphone and tablet, so often the manufacturer supplies them with different output current, for example, 1 and 2 A. However, a value of 2 A is reached when only one device is charging, so when two gadgets are connected, most likely both ports will give 1 A.
How to charge the power bank?
Not only does the external battery lose energy, charging your gadgets, it is also subject to the process self discharge. When you do not use the battery, it loses an average of 5% charge in two weeks. Moreover, the battery capacity tends to decrease with time, especially if the device is actively used: a quality product loses 15% capacity per year, and cheap models lose all 35%. For charge level control All batteries are equipped with LED indicators (3-4 bulbs). Advanced version - a small display that shows the exact state of charge of the battery in percent. 
By way of charging External batteries can be divided into the following groups:
- those that are powered only by the USB port of the computer;
- those that can receive power from the computer and from the network by connecting to a regular outlet.
What do you think, as an option more convenient? Naturally, the second. Actually, that is why the first type of batteries has almost completely disappeared from sale. Remember that charging the device from the computer is much longer, and having a USB Type-C port speeds things up a bit. Some power banks can be charged in record time thanks to the fast charge feature. 
An interesting option - charging with solar cells. For now, it’s too early to say that the sun’s energy will be a complete source of battery power for an external battery, but the solar panel at the end of the device can compensate for the self-discharge.
Pay attention to external batteries with flashlights. They will be useful in the event of a power outage and trips to nature.
One more thing. Most mobile gadgets today are equipped with a microUSB connector, and manufacturers often bundle their devices with a universal cord, and Apple owners and relatively old devices should pay attention to models with a set of universal adapters. Most users can not worry, as will be able to use the cord for charging, which comes bundled with a smartphone.
Top power bank 2017: a dozen of the most powerful
When choosing an external battery, it is better to trust the products of famous brands: so there are more chances that the real characteristics will correspond to the stated ones, and the battery will surely live for several years. The market for external batteries today is supersaturated, manufacturers and models are represented on it so much that it cannot be described. Among reputable manufacturers can be identified Xiaomi (absolute leader of the sphere), ASUS, Momax, Samsung, TP-LINK, HIPER, Canyon and Remax. Choose the best power bank is not easy, given the different user requests, so we will try to please everyone and find interesting models in different "weight categories".
Xiaomi Mi Power Bank 2 10000
Xiaomi external batteries are a guarantee of quality. The manufacturer seeks to make functional, durable and practical equipment at an affordable price. Xiaomi smartphones have long been called Chinese Apple, and in the world of portable batteries, the company confidently ranks first and offers users several models at once. This option is the most balanced in price, quality and battery capacity. Among the main advantages metal case, fast charging, streamlined shape, the presence of a USB cable - micro USB. In addition, happy rich color range and the presence of protection against overheating, overload, short circuit. Charge indicator - LED. The guarantee that your Xiaomi is original is a special code that is applied under the scratch strip; you can check it on the manufacturer’s website. 
Xiaomi Mi Power Bank 5000
An analogue of the previous model, but more compact, and therefore more mobile. Easily hidden in a pocket or purse and at the same time be able to recharge an average smartphone 1-1.5 times. There is no quick charge function, but there is a wealth of possible colors and protection against overheating and overloads. Charging a smartphone with such a battery, they can continue to use normally.
Xiaomi Mi Power Bank 20000
Xiaomi has created external batteries for all needs, and for those who need a large amount of energy, offers this 20,000 mAh beast. He can simultaneously charge two devices, and the plastic for the design of the case was chosen only because the battery in the metal would have turned out too heavy. Thanks to the Qualcomm Quick Charge 2.0 technology, you can quickly charge the power bank, there is protection against overheating and overload, the LED indicator that you have to accept.
Recently, the company released a model with very similar characteristics - Xiaomi Mi Power Bank 2 20000. It received Qualcomm Quick Charge 3.0 fast charging technology, a maximum output current of 2.4 A and a Li-Polymer type battery, everything else is the same.
ASUS ZenPower 10050 mAh ABTU005
A good competitor to banks from Xiaomi was released by ASUS. Wrapped in metal, a small portable battery received a medium capacity that is quite sufficient in most cases, as well as protection against overload and short circuit. LED indicator, a huge selection of colors. To the metal case is not scratched, it is better to stock up on a cover for it.
HIPER XP17000
If you want to buy an external battery with premium appearance and broad functionality, this model is for you. Coverage done under the skin, around the device is edged chrome strip - the view is impressive. Performance characteristics are also encouraging, especially the capacity and amperage. Users note that there is no self-discharge. By all measures, one of the best power bank today.
Xiaomi Mi Power Bank 16000
A 16,000 mAh elongated metal bar replenished the range of legendary external batteries. Of the main advantages twoUSB-out with the ability to simultaneously charge two devices and several degrees of protection. Functions fast charging "banks" is not provided - the full recovery of energy will take about 9 hours. The device is qualitatively assembled and perfectly holds the charge, as evidenced by user reviews. The original device from Xiaomi is easy to check on the manufacturer's website. Beware of fakes.
HIPER EP6600
One of the significant advantages of the gadget - Big-eyed designThe device looks really cool (charge indicators are implemented like this). The device is compact, fully meets the characteristics declared by the manufacturer, and its self-discharge is low. The operation is simple, the bag fits easily, about the size of a smartphone with a diagonal of 5.2 inches.
The model received a decent capacity and considerable weight, despite its plastic case, and this, in turn, suggests that the manufacturer does not overestimate the characteristics. The device can be easily charged two devices at onceLED indication. When shopping, think twice whether it will be convenient to carry such a brick with you.
HIPER SP7500
A small, lightweight, compact and inexpensive paver bank also captivates with its appearance, because he dressed in leather. Build quality can only be praised, but the need for two ports with such a battery capacity remains in doubt. Excellent appearance is maintained for a long time, because the skin, unlike plastic and metal, is not so prone to scratches. The manufacturer has equipped the device with protection against deep discharge. It turned out a stylish and functional device.
TP-LINK TL-PB10400
Due to its shape, this cute paver bank will fit perfectly in a bag. Among other advantages: compact size and optimal capacity, as well as the ability to simultaneously charge your smartphone and tablet. Moreover, the device is equipped flashlightand in the kit comes with a case.
HIPER XPX6500
This device will become status accessorybecause it has small dimensions and is clad in leather. If you are looking for external battery with display, which will reflect the percentage of the charge, then this model should also interest you. For the sake of compactness, we had to sacrifice capacity, but rather the manufacturer pursued the goal of creating a small paver bank, which can recharge the smartphone 1.5-2 times if necessary.
HIPER MP10000
Completing our review of the best external batteries is another model from HIPER, which is interesting not only with two USB ports, a metal case and flashlightbut also the presence multiple adapters includedincluding on the old and modern Apple gadgets, as well as Nokia. There is even a card reader function, only, it is unlikely, it will be useful to someone.
Finally, we note that for the long life of your power bank, do not allow it to be deeply discharged. Charge it only with the current indicated in the specifications. At critically high and low temperatures, try not to charge or use the device if there is no vital necessity.
We all faced situations when the phone was not just discharged, but sat down at the most inappropriate moment. To overcome such situations, portable charging devices were invented. They are in demand, and therefore there are many low-quality or fake products on the market. In this article we will explain how to choose a Power Bank and, sorry, do not "fuck up."
Most of the problems and dissatisfaction among Power Bank users cause their poor quality. The main reason is that often these devices are bought for a small amount of money, not paying attention to the manufacturer and device capacity.
How much should a normal power bank
Quality Power Bank volume on 10.000 mAh worth by $17 and higher. For device on 20.000 mAh will have to lay out about twice as much. And this is about the most simple devices - without additional connectors, fashionable design or digital charge level indicator. We are now talking only about the purchase of portable charging on Aliexpress. If you decide to buy Power Bank in a store in your city, feel free to add 15-20% mark-up to the recommended price.
But you should not look only at the cost of the device. Often found in the sale of expensive and, judging by the description, with the elegant characteristics of turning banks, but with one small difference - an unknown manufacturer. These instances should be treated with double caution, as often the “businessmen” bargainers buy the cheapest devices but then cheat 3 prices on them and tell them that this is a very high-quality product.
Power Bank from which companies worth buying
Power Bank from Samsung, Lenovo, Xiaomi, Asus, Sony and other well-known brands will be several times more reliable, as large companies with a world name value their reputation. Do not forget that such a technique is a complex electronic device that can burn both the telephone and itself. But even here there are certain points that should be paid attention to. Famous brands are often faked, and the authenticity of the device cannot be verified in advance by ordering Power Bank from a Chinese online store. There is already worth paying attention to the rating of the seller, reviews of the store and the number of sales. Even better - order the device from the official stores of companies, some of which are present on Aliexpress.
You should also pay attention to the fact that many manufacturers place special codes on the boxes for devices with which you can verify the authenticity of the product.
What volume should buy Power Bank
As you have noticed, the Power Bank of a different size and with a different set of functions are represented on the market. It is clear that a device with a large amount of mAh will weigh more and cost more. We will not disregard the impressive size of such devices.
Large batteries are perfect for those who are often forced to travel and do not always have the opportunity to charge not only the phone, but also other mobile gadgets. In most of the “capacious” Power Bank, it is possible to simultaneously charge several devices at once (phone and tablet).
But what to do if you do not travel, and the Power Bank is needed only for emergency cases, so that the phone does not “die” in the near future, until you reach the outlet. In such cases, dragging a huge brick behind you, which is larger and heavier than the smartphone itself, is not entirely advisable. For such cases, the best solution would be a small Power Bank with a volume of 3.000 - 5.000 mAh. Devices with a small charge volume are much smaller in size, which allows some of the models to be worn in a key chain as a key ring. And on some models, on the other hand, there is a built-in flashlight, so that the device is multifunctional.
Pay attention to the strength of the output current, which affects the charging rate. For smartphones, 1A (ampere) will be quite enough, but for tablets it is preferable to use devices with a current of 2A or higher, otherwise it will take several times longer to fully charge.
Conclusion
On the market there is a huge amount of Power Bank from different manufacturers. Devices differ in volume and availability of bonuses (charge level sensor, multiple charging ports, original design). To choose the best device and do not lose, we advise you not to save, pay attention to the rating and reviews of the seller, as well as the manufacturer. A large amount of the charger should be chosen by travel lovers, and for everyday use there will be enough small batteries that can be hung on the keys instead of a key fob.
In most cases, people who are going to buy a bank face the same questions: How to choose a bank? What to look for?
I will try to give some tips on how to choose a bank based on your needs and what to look for.
First you should think do you really need a bank? First, imagine a situation where you really may need additional charge on your smartphone or other gadgets that can charge from USB, and how often you find yourself in such situations in your daily life. And only if you really need it, proceed to the choice of the model suitable for you.
So, what to look for when choosing a bank:
- Compatibility.
- Manufacturer
- Capacity
- Functionality
- Weight and size
- Design
Compatibility.
Be sure to pay attention that the input voltage required for charging your devices matches the output voltage of the selected model of the bank. You can watch it either on the network charger that came with your device, or in the instructions attached to it. For most modern gadgets, such as smartphones, tablets, action cameras, GPS-navigators, etc. the most common voltage will be 5V DC (5V DC), corresponding to USB specifications.
Current strength requirements are usually not as stringent. So, if you connect a device with a current requirement lower than the power bank can provide, nothing terrible will happen, the charge controller simply will not allow the charging current to exceed. If, on the contrary, a device requiring a higher current is connected to a power bank or a charger whose output parameters declare the maximum current lower than that required, for example, a tablet that consumes 2A during charging to an output of 1A, then the charging process will simply be longer , or the device will not be charged at all due to lack of power. However, this usually happens only with very specific devices like the iPad. Manufacturer
When choosing a manufacturer, first of all you need to keep in mind that Power Bank is a high-tech device.which consists not only of lithium-ion batteries, but also has certain protective systems in order not to destroy your gadget, not to burn yourself and please you with long-term and trouble-free work.That is why Power Bank is often called not just a battery, but a “stand-alone charger.”
Often, buyers make the same mistake - they buy chargers from unknown manufacturers, who don’t even mark their products with logos, being tempted by a low price. 
Unfortunately, in such cases, the actual capacity will often be several times less than declared.
So, the first thing you need to select well-known manufacturers. But there is a downside: the more popular this or that model, the more likely it will be fake. 
Capacity
Further, it is necessary to determine the required capacity of the bank. Think about how many charge cycles your device should provide? And multiply this figure by the battery capacity of your device and by a factor of 1.5. Do not believe those tables where you simply divide the capacity of the bank into the battery capacity of a particular smartphone. A power bank with a capacity of 10000 mAh can never charge a smartphone with a 3100 mAh battery three times. At best, it will be two and a half times, and in the majority - two or a little more than two times.
After all, the battery voltage of the bank, in most cases, is 3.7V (or close to it), and depending on the current level of charge, the batteries may differ in a greater or lesser direction. And therefore, it must first be upgraded to 5V, in order to comply with the USB standard, with a special circuit. Then it will transfer via cable to your smartphone, after which the charge controller in the smartphone will again reduce it to the required for direct battery charge. And at each of these stages there will be greater or lesser losses.
Functionality.
Crib banks
may differ also by functionality. Here is a small list of convenient, but in my opinion, non-mandatory functions: - Second USB port. It is convenient if you have the need to charge two devices at the same time.
- lED flashlight which may be useful to you, for example, in order to make it easier in the dark to find the charging socket of your smartphone or tablet.
- digital charge level indicator
, because it is possible to more accurately estimate the exact percentage of the level of the charge of the bank, than on the flashing LEDs. Weight and size
The size and weight of a bank is proportional to its capacity. The greater the capacity of the batteries installed in the bank, the greater its weight and size. Also, the type of batteries installed in it affects the weight and size of the bank, the lithium-ion battery (li-ion) will be slightly larger and slightly heavier than the lithium-polymer battery (li-po) battery of similar capacity.The material from which the casing of the crib is made will also influence the weight: the casing of the crib will be heavier than that of plastic.
You should also consider the compliance of the declared capacity and weight of the bank. Often this makes it easy to identify most of the banks with clearly overestimated "Chinese optimism"Capacity, because poverbank with a capacity of about 10,000 mAh will weigh 200-260g. And twice as large capacity (20000mAh), respectively, about twice as heavy. So if the capacity is clearly indicated, it does not correspond to the weight - you should not buy such a bank.
However, the weight does not guarantee that there are no batteries with a capacity smaller than that indicated in the specifications, but at least it makes it easy to identify a clear discrepancy in the characteristics.
Design
The design of a crib can also play an unimportant role in choosing, because to someone characteristics are important, but for someone “ he is red!"© therefore, crib banks are produced not only in various colors and shades, but also in various forms, even to anime film characters, for example, a poverbank in the form of an anime film character" My Neighbor Totoro» ( My neighbor totoro).
Have different 
people have different needs, including in bankers: someone needs a small bank that they carry with them just in case", Such as mocreo lavo 2500mAh, thin, light, easy to fit into a purse, and that will help out easily in a situation " i’m not going home yet, the phone is setting, and I am waiting for an important call"And which will easily charge your smartphone to a level sufficient 
to not miss an important call. Well, for someone, you need to recharge your gadgets many times away from the outlet, for example, to charge a GPS navigator, walkie-talkies, etc. during a hike, and then more capacious models, such as Teclast T200E at 20000mAhor even a few.
