How to choose a PowerBank

How to choose a powerbank

Updated: November 10, 2023

A portable charger or PowerBank allows you to charge your phone, tablet, smart watch or wireless headphones anywhere. Therefore, the PowerBank comes in handy when traveling, camping away from home or when there is no access to an electrical outlet. The PowerBank is a universal charger and can include many useful features. The guide in this article will help you understand all the available features and choose the best PowerBank model.

What is a PowerBank

PowerBank refers to universal mobile chargers. All PowerBank models are equipped with an individual power source – rechargeable battery. Therefore, PowerBank can accumulate and store energy, and when necessary – give the energy to recharge another device. Basic PowerBank models are designed to recharge mobile electronics: phones, tablets, smart watches and fitness bracelets, music speakers, IP cameras, cameras and video cameras. PowerBank models with high output charging power can power laptops and mobile computers. PowerBank models with high output voltage can also be used for car battery starter.

portable charger
Power Bank USB ports.

What to look for when choosing a PowerBank

When choosing a PowerBank you should pay attention to the following main parameters:

  • Type of assembly. Factory assembled or custom assembled.
  • The number of USB ports for connection. How many devices can be charged simultaneously.
  • The capacity of the built-in battery. How much energy the rechargeable battery can store and store.
  • Efficiency of operation. Quality of energy conversion.
  • Charging capacity. Charging power input and output.
  • Safety. Prevention of breakdown in case of overloading, overheating or other malfunction.
  • Charging indication. Visual indication of remaining battery power.
  • Type of case material. What materials the PowerBank case is made of.
  • Additional features. Minor features for extending the capabilities of the PowerBank: built-in modem, flashlight, SD card reader, etc.

Assembly type

There are two types of assembling PowerBank:

  • Factory Assembly.
  • Custom assembly.


Factory-assembled PowerBanks have a battery installed at the factory. Such PowerBanks are ready to work immediately and do not require any user modifications. In addition the constructional features of each ready-made model often do not require the user modification or self-repair of the PowerBank. Therefore, to disassemble the case of some models PowerBank can be only in the service center.

factory powerbank
Power Bank Packaging.

Another problem of factory models is the battery capacity. The user must rely on the honesty of the manufacturer. Well-known brands rarely overestimate the battery capacity inside the PowerBank. Meanwhile, little-known or dishonest manufacturers often list unreliable PowerBank battery capacity. As a result, the user buys a 10,000 mAh PowerBank with a real capacity of 7,000 or 8,000 mAh.

factory assembled powerbank
Power Bank with built-in screen.

Another problem with factory PowerBanks is the condition of the battery. Li-Ion or Li-Pol type batteries are used for energy storage. Under the influence of high or low temperatures, the chemical composition inside the battery deteriorates. Therefore, improper transportation and storage of PowerBank shortens the life of the battery. If a PowerBank has been in storage for several years, then the quality of the battery will be significantly worse than the same PowerBank produced a few months ago.

Power Bank USB ports.

Custom Assembly

There is no battery installed in the PowerBank for custom assembly. Such models represent only the case with the element base. You have to install the battery yourself before using it. Therefore, the user can choose the optimal battery in terms of quality and capacity.

custom-built powerbank
Power Bank case for custom build.

On sale you can also find a separate element base for installation in a custom case. You can use a ready-made case or made on a 3D printer. If you build it yourself you can also add various modules: active cooling, flashlight, wireless charging, screen with charge indicator or USB tester.

batteries inside the powerbank
4 batteries 18560.

At the same time the cost of custom assembling PowerBank is always higher than that of prefabricated models. The reason is the high retail price of batteries and case, as well as shipping costs. Sometimes the custom assembly is 1.5-2 times more expensive than the prefabricated PowerBank. Therefore, for custom PowerBank assembly it is reasonable to use old batteries from phones or laptops.

Number of USB ports to connect

All PowerBanks have a different number of USB ports with a specific purpose:

  • Input: only charging the battery inside the PowerBank.
  • Output: Only transfer power to the connected device.
  • Universal – Input and Output: Charging the PowerBank or transferring power to a connected device.

One or more USB ports always work only for charging PowerBank. Number of external USB ports up to 8. The number of universal USB ports can be 2 or 3. Manufacturers indicate the purpose of each USB port on the PowerBank and in the specification.

3 usb powerbank
Power Bank USB ports.
usb port assignment
Power Bank USB port types.

Cheap PowerBank models and models with battery capacity up to 5000 mAh have only 2 USB ports. One USB port is used only to charge the PowerBank and the second USB port is used to charge the connected device.

Most PowerBank models contain 2-4 USB ports. In this case, 2 USB ports are necessarily used for external device connection. Another 1-2 USB ports support universal operation or only charging the battery inside the PowerBank. If the PowerBank has only 2 USB ports, then 1 or both USB ports support universal mode of operation.

2 usb in powerbank
Xiaomi Power Bank USB Ports.

PowerBank models with an internal battery capacity of 22500-80000 mAh can contain up to 11 USB ports. For example, the Baseus Amblight PowerBank has 7 USB ports: 5 USB ports can be used for external connection, and 3 USB ports for charging the PowerBank.

When choosing a PowerBank, you need to consider how many devices you need to charge at the same time. If you need to charge only one smartphone, then a model with two USB ports is enough. If you need to charge your phone, tablet, wireless headphones and fitness bracelet, then you need a PowerBank with 3-4 USB ports.

The type of USB ports does not matter. All PowerBanks always have a universal USB-A port. For fast charging, USB Type-C may be present. MicroUSB and MiniUSB are less common and are only used for charging PowerBanks.

usb connectors
Place to install the strap.

Built-in battery capacity

The higher the battery capacity of the PowerBank, the more power you can store. On sale you can find PowerBanks with battery capacity up to 80000 mAh. At the same time the most popular models for 10000-30000 mAh. Because these PowerBank inexpensive, fairly compact and lightweight. A battery capacity of even 10,000 mAh is stably enough to fully charge once any smartphone and most tablets.

powerbank battery capacity
Power Bank Characteristics.

The battery capacity of the PowerBank should be chosen based on a 30-35% loss of capacity for energy conversion during charging. Therefore, do not consider a PowerBank with a battery less than 10,000 mAh. For frequent charging of several phones or laptop charging PowerBank of 30000-50000 mAh capacity are better. And for long trips or travel you can consider PowerBank models more than 50,000 mAh.

Performance Efficiency

All PowerBanks give off less power than they can store. For example, a 20,000mAh Baseus Blade can give away about 12,000mAh of power at full power, while a 10,000mAh Baseus Adaman2 is about 5,800mAh. This difference is due to the efficiency of operation when voltage conversion is required. In addition, the amount of energy given away decreases slightly each time due to the decreasing battery life inside the PowerBank.

poerbank output performance
Measured capacity of the built-in battery.

The PowerBank uses Li-Ion or Li-Po batteries with a rated voltage of 3.7 volts. A minimum voltage of 5 volts is required to charge a phone or other device. And when using the fast charging technology, a voltage of up to 20 volts is required. Therefore, the voltage is increased to the required value with a certain power conversion factor. The higher the ratio value, the lower the energy loss. The energy conversion value is mainly influenced by the chips and electronic components used by the manufacturer. The best models of PowerBank have an energy conversion factor of up to 85%, in most cases the value is 65-75%, and in the cheapest models sometimes 62% or lower. The power of the charger also affects the amount of energy output. The higher the power output, the less power the PowerBank will give out.

powerbank efficiency
Power Bank Specification. The nominal capacity of the Power Bank battery.

Some manufacturers list the power conversion factor on the data sheet or on the official website. Sometimes the PowerBank’s case specifies the capacity that the PowerBank can give out at a certain voltage, usually at 5 volts.

Charging power

The higher the power value, the faster the energy can be transferred. Therefore, the charging power of the PowerBank should match the charging power supported by the phone. If your phone supports charging up to 30W, then the PowerBank charging power should be 30W or more. If the phone supports 30W charging, but the PowerBank’s charging power is 22.5W, then the phone will receive no more than 22.5W of power. Also the PowerBank must support the same fast charging standard as the phone. Otherwise, the maximum charging power of your phone will be 5 or 10 watts. You can find out the supported by PowerBank fast charging standards in the specification or on the official website of the manufacturer.

There are always two power values indicated on the PowerBank case:

  • Input – the charging power of the battery inside the PowerBank.
  • Output – the charging power of the connected devices.
powerbank with slow charging
The power output of a cheap Power Bank.

For PowerBank without fast charging support, only the power of each USB port and the total power when all USB ports are used is indicated.

powerbank with fast charging
Xiaomi Power Bank output power.

For PowerBank with fast charging technology several power values with different parameters of current and voltage are indicated: 5.1V/2.4A, 9V/1.6A, 12V/1.2A etc. The output power is intelligently regulated and corresponds to the charging power supported by the phone. Maximum power output is only available when using one USB port. If you use two USB ports the total charging power is halved or one USB port gets more power and the other USB port gets less power. Using three or more USB ports results in a power split between all USB ports.


All PowerBanks contain several safety mechanisms to prevent failure. The electronics take into account critical malfunctions and some external factors and shut down the PowerBank until the malfunction is corrected. The more protective mechanisms the PowerBank contains, the better the reliability and safety of the device. Here are the most common problems encountered when using a PowerBank:

  • Overheating.
  • Short circuit on output.
  • Input short circuit.
  • Detection of metal objects on the wireless charging pad.
  • Overvoltage in battery input.
  • Battery overcharge and deep discharge.
  • Output and input overcurrent.
  • Input and output voltage overshoot.
  • Battery overloading.

Supported protection mechanisms may be specified by manufacturers in the data sheet or on the official website.

Charging indication

All PowerBanks include a charging indication to check the current battery capacity. The exceptions are the cheapest PowerBanks or models with a battery capacity of up to 3000 mAh.

Inexpensive PowerBank models or for additional cost savings use a 3 or 4 LED indication. This indication allows you to know only the approximate battery capacity. If 4 LEDs are lit, then the battery is fully charged, 3 LEDs indicate 75% charge, 2 LEDs indicate 50% charge, and 1 LED indicates 25% charge or less.

powerbank indication
LED battery charge indicators.
powerbank light indication
LED battery charge indicators.

A detailed indication of the current charge is shown on the informative screen. The built-in screen displays the current charge as a percentage. Cheap models often display only a few values on the screen – the current percentage of charge and the charging or discharging status. The screen of more advanced models additionally displays the fast charging status, current voltage, and amperage. Some models may display a notification with the current fault, helping you to quickly troubleshoot the problem yourself.

screen with display of remaining charge
On-screen battery charge indication.

Case Material Type

The PowerBank case is mainly made of plastic or aluminum alloy. Some models are decorated by manufacturers with fabric, nylon and leather inserts. Such inserts are of no practical use.

The most common housing material is plastic. The advantage of plastic is a low price. Also the plastic case can be painted in any color. However, plastic is quickly covered with microscratches and poorly dissipates excessive heat. Therefore, charging with high power can lead to overheating of the PowerBank and reduce the service life.

plastic body
Power on and off button.

Aluminum alloy is a less common housing material due to its high cost. At the same time, aluminum is less susceptible to micro-scratches and is better at dissipating excess heat. Also aluminum housing is more durable than plastic.

There are also models with combined materials. The main frame is made of aluminum, and a plastic cover is mounted on top. In the dustproof models PowerBank also uses rubber for stopping the USB ports. The same rubber is used in the form of inserts to absorb the energy when the PowerBank is hit or dropped on the ground.

Additional Features

Some PowerBanks contain additional features needed for specific uses.

USB hub. You can use USB ports of PowerBank for connection of different peripheral devices. This function will be useful if there are not enough free USB ports in your computer or notebook.

Dust and water resistance. Resistant to moisture and dust is useful for using PowerBank in places with harsh weather conditions. The same resistance to moisture and dust is useful for camping, hiking in the mountains or in the woods.

Solar panel. Built-in solar panel allows you to slowly charge the PowerBank during the day in the sunlight. The solar panel will be useful in emergencies, hiking and camping.

Wireless charging. An extra place to charge wireless devices: phones, smart watches, wireless headphones, etc.

Through charging. With end-to-end charging function, PowerBank can charge and give stored energy to connected devices at the same time. Therefore, PowerBank with end-to-end charging function can be used as a backup power source for Wi-Fi routers or IP cameras.

Magnetic MagSafe mount. Magnetic mount will provide a secure hold for charging Apple phones with MagSafe function. Some PowerBank models allow you to charge phones with a case that simulates the presence of MagSafe.

Low current charging. The low current charging feature allows you to charge devices that do not require a lot of current: fitness bracelets, smart watches, wireless headphones, etc. Sometimes the low current charging feature is tied to a specific USB port.

Manual voltage adjustment. This feature allows you to switch the voltage from 5 volts to 12 volts or select the desired voltage manually. Often the voltage setting is necessary to charge older laptops that do not support today’s fast charging standards.

Built-in USB cable. PowerBank models with a built-in USB cable have a place to fix one or more USB cables with different plugs. Built-in USB cables are impossible to lose. Also, built-in USB cables allow you to increase the number of simultaneously charged devices.

Flashlight. A small flashlight with directional light. Can be handy for lighting the way in the evening or to shine a light in a dark room.

Headlamp. Built-in LED panel or several LEDs with a diffused glow. The luminaire can be used for additional or emergency lighting.

Built-in charging plug. The built-in plug allows you to plug the PowerBank into the socket without the charger. This feature comes in handy for traveling when you need to save on the number of gadgets and chargers.

USB Tester. Built-in PowerBank USB tester allows you to monitor various parameters: energy consumption of the phone, energy consumption, etc.

Built-in card reader. Card reader can be used for storing and sharing files while the phone is charging.


The guide collected in this article will allow you to understand all the parameters and choose the optimal Powerbank model. However, it is not possible to find a universal model with all the necessary features. Therefore, to get all the necessary features you may need to buy several different models of Powerbank. If you want, you can build your own Powerbank. On sale you can find modules with a different number of USB ports, support for modern fast charging standards, type of charge indication, etc.

And what kind of Powerbank do you use? Write in the comments, did you have to assemble your own Powerbank or do you use only the Powerbank factory assembled.


About the author

Alex Gustman

My name is Alexander.
I am the author of articles, reviews and videos on the YouTube channel of I have been testing various electronic devices, mobile games and Android applications since 2012.

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