Which power bank to buy? Powerbanks Test 2021!

External batteries are now some of the most popular accessories for mobile devices. What are the characteristics of these devices and how to choose the right model? For these and other questions Batna24 conducted its comparative test and selected the best models for you.

With almost every generation of smartphones, manufacturers increase the capacity of built-in batteries. But still, with intensive use, most models are still exhausted by the end, if not sooner. The reason for this is the increase in screen diagonals, which require higher power consumption, as well as efficient, not only in terms of performance, but also power consumption, chipsets.

Due to the increasing energy consumption by mobile devices (smartphones) and the spread of tablets, currently external batteries are very popular with a USB connector or sockets, which are also sometimes called powerbanks .

Depending on the capacity of the batteries, they can charge modern smartphones several times or provide a full charge to even powerful 10-inch tablets. The external batteries can be used to charge any device that uses a USB connection for this purpose, or to provide power (USB flashlights, USB fans, etc.).

All external batteries, with few exceptions, contain Li-ion or Li-pol cells. The choice of this type of cells is easy to explain, because such cells are able to deliver high current, are free from problems related to the "memory effect", and have a good capacity per unit volume.

In addition to batteries, powerbanks also contain a special controller that provides battery voltage conversion to 5 volts, 9 volts, 12 volts, 15 volts, and even 20 volts on USB connectors, controls overloads, monitors battery health, provides wireless charging, etc.

Battery capacity in mobile devices is most often stated in non-system mAh units. For simplicity, for example, a 1000 mAh value means that the battery is capable of delivering 1000 mA or 1 A of current for one hour (or 0.5 A for two hours). It's not that simple though, you can't charge a 1000 mAh battery 10 times with a 10000 mAh powerbank. Why not?

If we discard the option where an unscrupulous manufacturer (found in various "unnamed" devices) knowingly misrepresented and inflated the data, when talking about charging smartphones or tablets from external batteries with a USB connector, with a very rough calculation you should subtract about 35% of the stated capacity of the powerbank. This is the total amount of charge that the battery of the mobile device you are charging with the powerbank can store. With a capacity of 10,000 mAh, the powerbank allows you to charge a 2100 mAh smartphone battery three times or a 6500 mAh tablet battery once.

Where does the rest of the energy go? It's mainly used to heat the powerbank's controller, which raises the voltage of the battery cells to about 5V (USB port voltage), to heat the charging controller in the smartphone itself, which converts the voltage and currents from the USB port to those needed to charge the smartphone battery, and to heat the batteries in the smartphone and powerbank.

For testing and validation, we took powerbanks ranging from 10000 mAh to 20000 mAh, from leading mobile manufacturer Xiaomi and a new manufacturer of various home and professional devices Extralink, which has recently shown its good side. From Xiaomi we have taken powerbanks like Mi Redmi Power Bank, Mi 18W Fast Charge Power Bank 3, Mi Wireless Power Bank, Mi Power Bank 3 Pro and Mi Wireless Power Bank Essential. Extralink, on the other hand, offers two powerbanks: Extralink ZMI PowerPack 20000 High-Speed rechargeable Li-Ion Portable Power Bank and Extralink ZMI PowerPack Aura 20k USB-C Power Bank.

Procedure for preparing the powerbank for the test:

The powerbank was then discharged using a constant load calculated to give a load of about 10W (2A) for a voltage of 5V. Depending on the actual voltage at the time, the load value was slightly variable and differed for each powerbank.

Let's go to the tests:

Xiaomi Redmi Power Bank model PB100LZM is a device with a lithium-polymer battery capacity of 10000 mAh. It features bi-directional fast wired charging, short-circuit protection, surge protection on the output and input, protection against incorrect connection, protection against overcharging and over-discharge, and is temperature resistant, Xiaomi engineers have also provided it with a low-voltage charging function, i.e. to charge devices that need less power, just press the battery check button twice to enter the 2-hour low-power charging mode. Available in white. In the durable plastic housing there are two USB type A sockets for fast wired charging up to 10W and one type C and micro USB for charging the powerbank itself, which according to the manufacturer takes about 4 hours.
Button to check the status of the powerbank capacity located on the side, allows you to check the power status with 4 LEDs. And so 0-25% will light up 1 LED; 25-50% 1 and 2 LED; 50-75% 1,2 and 3 LED; 75-99% 1,2,3 and 4 LED.
The package contains a device with a size of 150.5 mm x 73.6 mm x 15.1 mm and a weight of 0.242 kg, a USB-A to micro USB cable/adapter about 31 cm in lenght (measured together with the plugs), a user manual in an abbreviated version (unfortunately not in Polish), and information about the product being approved for the Polish market. Compatible with the most popular smartphones smart devices. The manufacturer also informs that a full power bank will charge approximately 1.75 x Redmi Note 7 or 1.75 x Mi9T Pro or 2.2 x Mi 9 or 2.3 x iPhone XS.

Charging:

At a charging voltage of 5.14V, the battery from a fully discharged state took 7684mAh, which gave 39.2Wh As you can see in the graph from about halfway through the charging time, there was a gradual decrease in charging current in the charging process basically from the very beginning.

Discharge:

The discharge process started at 5.16V, the powerbank gave out 5404mAh which is 27.9Wh

Xiaomi Mi 18W Fast Charge Power Bank 3 model PLM13ZM This device has a lithium-polymer battery capacity of 10000 mAh. It has the function of bidirectional fast wired charging, short-circuit protection, surge protection on the output and input, protection against incorrect connection, protection against overcharging and over-discharge, and is temperature-resistant, Xiaomi engineers have also provided it with the function of low-voltage charging, i.e. to charge devices that need less power, just press the battery check button twice to enter the 2-hour charging mode with low energy consumption. Available in two colors: silver and navy blue. The durable aluminum alloy casing houses two USB type A ports for fast wired charging up to 18W and one type C and micro USB port for charging the powerbank itself which takes about 4 hours.

You will also find here a button to check the capacity of the powerbank, which will be indicated by 4 LEDs. And so 0-25% will light up 1 diode; 25-50% 1 and 2 diode; 50-75% 1,2 and 3 diode; 75-99% 1,2,3 and 4 diode.

In the box you will find, in addition to the device of course, which size is 147.8 mm x 73.9mm x 15.3 mm and weighing 0.275 kg, a USB-A to micro USB cable about 31 cm in lenght (measured together with the plugs), a shortened user manual (unfortunately not in Polish), and information about the approval of releasing the product on the Polish market.

According to the manufacturer, we will charge the Mi 9 1.9 times; 1.6 times the Mi 9T Pro and 2.2 times the iPhone XS with it.

Charging:

The charging process yielded a value of 5107mAh at a charging voltage of 8.92V, resulting in 45.62Wh. It is worth noting that the powerbank achieved a 90% charge level after just 4 hours and 28 minutes.

Discharging:

With a discharge voltage of 5.12V we got 6368mAh which is 32.65Wh in 3 hours and 16 minutes.

Mi Wireless model PLM11ZM from Xiaomi Communicactions Co., Ltd is closed in a compact black housing made of aluminum alloy, corrosion-resistant battery with a lithium-polymer cell with a capacity of 10000mAh. It supports Quick Charge technology up to a maximum power of 18 watts. According to the manufacturer automatically adjusts the power output to a safe level of charging devices with technologies such as QC3.0 / QC2.0 / BC1.2. and so in 1 hour 25 minutes you can charge Mi 9 and in 1 hour and 55 minutes iPhone XS. It also has a function of wireless charging (QI certificate) by induction up to max 10W and from manufacturer information we will learn that this way we can charge phones in 2 hours - Mi 9 and in 3 hours 20 minutes iPhone XS. The device is equipped with 2 inputs, one USB type C and one USB 2.0 type A, as well as LEDs indicating the power status of the powerbank: 1 LED; 25-50% 1 and 2 LEDs; 50-75% 1,2 and 3 LEDs; 75-99% 1,2,3 and 4 LEDs and one LED indicating that the device is turned on, and a button with which you can check the status of the energy storage (when you press it, the LEDs light up informing you about the amount of energy in the powerbank).

It also has short circuit protection, temperature resistance, input and output surge protection, protection against overcharging and over-discharge. Thanks to it you will be able to charge 3 devices at the same time, including thanks to the USB type C input also a laptop.

In the box you will find, the device with the size of 148 mm x 72 mm x 18.4 mm and weighing 0.308 kg, and a micro USB cable with length of about 31 cm (measured together with the plugs), a user manual in a shortened version, the user guide (unfortunately not in Polish), and information about the approval of the product for the EU market.

Charging:

With a charging voltage of 8.91V we obtained 5503mAh which gives us 49.05Wh at 6 hours 13 minutes. Charging to over 90% capacity, we obtained a time of 4 hours 9 minutes (5393mAh)

Discharge:

In the discharge process, we got an output voltage of only 4.59V (this is due to the need for a USB adapter) which gave back 6845mAh which gives us 31.44Wh with a time of 3h 55 minutes.

Mi Power Bank 3Pro model PLM07ZM From Xiaomi Communicactions Co., Ltd is closed in a compact black corrosion-resistant housing battery with a lithium-polymer cell with a capacity of 20000mAh. Designed according to GB / T 35590-2017 standard with Quick Charge 3.0. The device is equipped with 3 USB inputs. One USB Type C providing bi-directional fast charging with a power of 45 watts and two USB Type A, each of which individually can provide fast charging in standards 5V 2.4A / 9V 2A / 12V 1.5A while using. And there are also 4 LEDs to indicate the energy storage. And so 0-25% will light up 1 diode ; 25-50% 1 and 2 diode ; 50-75% 1,2 and 3 diode ; 75-99% 1,2,3 and 4 diode and a button with which you can check the status of the energy storage (after pressing it, the diodes begin to light up informing about the amount of energy in the powerbank).

Temperature resistant , has surge protection on the output and input , as well as short circuit protection , incorrect connection protection , overcharging and over-discharge resistant , with PTC protection . Thanks to it, we can charge small devices such as smartphones, fitness bands, smartwatches, headphones, etc., as well as tablets, laptops, and tablets. With it, we can charge small devices such as smartphones, fitness bands, smartwatches, headphones, etc., as well as tablets, laptops, but only compatible with this device (the list can be found on the manufacturer's website) In the package you will find, in addition to the device of course, which size is 153.5 mm x 73.5mm x 27.5 mm and a weight of 0.44 kg, also a USB-A to USB-C cable / adapter with a length of about 31 cm (measured together with the plugs), user manual in a shortened version, the user guide (unfortunately, not in Polish), and information about the approval of the product for the EU market.

According to the manufacturer we will charge it in 11 hours using a 10W charger or 4.5 hours using a 45W charger , and with this fully charged device we will charge 4.3 times Mi Mix 2S and as much as 7.3 times iPhone 8 . To charge devices that need less power, simply press the power check button twice to enter the 2-hour low power charging mode.

Charging:

The charging voltage was 14.88V and we obtained 6165mAh with it which is 91.77Wh in a time of 5h 32 minutes. A significant drop in charging parameters occurred after a time of 4h 29 minutes for a value of 6148mAh.

Discharge:

In the discharge process, we got an output voltage of only 4.87V (this is due to the need for a USB adapter) which gave away 14543mAh which gives us 70.85Wh with a time of 7h 49 minutes.

Xiaomi 10000mAh Mi Wireless Power Bank Essential WPB15ZM It's encased in a compact black or white aluminum body, with a corrosion-resistant lithium polymer cell battery with 10000mAh capacity. It features bi-directional fast charging with a maximum power of 18W and an intelligent foreign object detection (FOD) system. Additionally temperature resistant, with short circuit protection , input and output surge protection, incorrect connection protection, and overcharge and over discharge protection and PTC protection circuits.

Supports Quick Charge technology to the maximum power of 18W. and with Qi protocol support allows for simultaneous wired charging with maximum power of 18W and wireless inductive charging with maximum power of 10W. The device, which measures 147.9mm by 71.6mm by 16.6mm and weighs 230 grams, according to the manufacturers, is able to charge the iPhone XS wirelessly in 3 hours and 20 minutes and the Mi 9 about 2 hours, and wired charge the Mi 9 about 2 times and the iPhone XS 2.5 times.

The device is equipped with 2 inputs, one USB type C and one USB 2.0 type A, as well as 4 LEDs indicating the power status of the power bank: 1 LED; 25-50% 1 and 2 LEDs; 50-75% 1,2 and 3 LEDs; 75-99% 1,2,3 and 4 LEDs and one LED indicating that the device is switched on, and a button with which you can check the status of the energy storage (after pressing it, the LEDs light up informing you about the amount of energy in the powerbank).

In the package you will find, in addition to the Xiaomi 10000mAh Mi Wireless Power Bank Essential of course, a micro USB cable of about 31 cm in length (measured together with the plugs), a user manual in an abbreviated version, user guide (unfortunately not in Polish), and information about the product being approved for the EU market.

Charging:

At 8.91V we got 5162mAh which is 46.09Wh in 4h 51minutes. This power bank relatively quickly reached over the 90% threshold with a drop in charging parameters at 3h 43minutes for 5085mAh

Discharge:

Discharging the powerbank achieved 5.02V which gave us 6598mAh at 33.15Wh in 3h 26 minutes.
This is the fastest Power Bank of the tested, but not the best.

ZMI Power bank 20000mAh model QB820 by Extralink is a new external battery with good parameters. Its capacity of 20,000 mAh or 72 watt-hours can support a mobile lifestyle. The product provides the user with extra USB ports to use when needed. And its elegant indigo patinated casing honors discreet sophistication and professionalism. The device has multiple safeguards against problems such as: short circuiting, overcharging, over-discharging, overheating. The USB-C port, uses bi-directional power delivery (PD) over a wide voltage range (5 to 20 volts) for fast incoming and outgoing charging with a maximum power of 45 watts. Compatible with almost all smartphones , tablets, MacBook models and other USB devices on the market.

In the package you will find in addition to the device, a thank you for your purchase with information to share your review of the product on facebook in English and the user manual in Japanese, English, Russian and French, and two cables of which the first one on one side ended with a USB-A tip and the other with USB-C and USB Micro with the possibility of overlapping one another and the second with USB-C on both ends, the cables should be a little thicker.

A single press of the led status button will wake up the device from sleep state, but will not turn it off if it is already on. The power bank will charge smartphones, tablets, laptops or other devices. Simply plug it into the Power Bank's USB-A or USB-C port using the included charging cable. When the device is being charged, the LEDs on the device will flash and then they will shine continuously. The manufacturer suggests using min such power adapters to charge the Power Bank: MacBook (2015 or later), MacBook Pro (2016 or later) Apple USB-C backup power adapter (29W, 30W, 61W or 87W) Google Pixelbook USB-C power adapter ( 45W). ZMI PowerPlug Turbo USB-C charger (45W) Google Pixel USB-C power adapter (18W). The power bank uses a lithium-ion cell. The weight of the device is 405 g , operating temperature: 0°C ~ 45°C and dimensions: 160.4 × 81.8 × 21 mm. Cell Capacity: 70.2 Wh/72 Wh 3.6V 19500 mAh/20000 mAh Rated Capacity: 12000 mAh (5V/4.5A).

Charging:

The second external battery from Extralink is ZMI Aura 20K model QB822. The device has a lithium-ion cell, charging and discharging micro USB and USB-C inputs and USB-A and USB-C outputs, as well as protection against overcharging. Maximum capacity is 20000mAh 3.7V 74Wh, nominal capacity 12,600mAh 5V 63Wh(5V~4.5A);4,100mAh 15V 61.5Wh(15V~1.5A). Operating temperature range from 5-35 °C, dimensions: 149.3x70x25 mm. The manufacturer also provides information about the charging time: 9V~2A charger to 6 hours: 5V~2A charger to 10 hours.

When connected to the power supply, the arrow symbol ↑ is displayed and then the power level in digits, in case of incorrect charging, ''Er'' is displayed. When charging e.g. a phone or other digital devices, the display will show numbers for the first few seconds and then the arrow ↓ for approx. 4 seconds and then the display switches off, press the power level button twice to make it visible again. If the display shows LP for a few seconds before it goes out, it means that the power bank is in the low-current charging mode. When charging devices such as headphones, smart bands, etc., the maintenance-free power of the product is about 25%-50% and the device should be kept in this mode if you do not use it for a while to extend its life.

In the box you will find in addition to the device, a thank you for your purchase with information to share your review of the product in English and the user manual in Japanese, English, Russian and French, and a USB-A tip to USB-C cable, which should be a little thicker and longer.

Charging:

After summarizing all the tests and looking at the data obtained in the summary table, we chose the best performing one in these tests. It was the Extralink ZMI Aura 20K USB-C model QB822, showing the best results, as well as a good battery capacity that will certainly last for several charges of your smartphone, tablet or other mobile devices.
However, everyone can choose a powerbank with the right number of outputs, type of connectors, output power and other characteristics. And let's not forget that in addition to the proven powerbank, there is a huge number of companies that produce powerbanks, many models with different functions. We have selected the most popular and most interesting models.
A full charge of modern smartphones with active use is not enough even for one day. And the issue of finding an extra charge, when there are no outlets nearby, is very important. To the rescue comes Power Bank, which is a simple and easy way can get rid of these additional worries.

An external battery is a great solution for any occasion: travel, hiking or work in the field. All that remains is to choose the right model.