Pocket energy test: one of the powerbanks would charge almost nothing

Nikola Tesla

For non-users of smartphones and tablets, they are almost indispensable. But do powerbanks really have capacities given by the manufacturer and how can they deliver the promised current? We tested trnct powerbank from nine manufacturers. Let’s advise how to use them first.

Sometimes we have a lot for foreign foreign names and English, but the power banks are an example of a device that the Czech name did not get. So we could give them a portable battery pack for charging a USB device, but we’d rather stick with the established English bank’s anglicism.

Powerbank is a portable source of electricity with one or more USB ports, which can charge the device that can be charged with a USB cable, most often smartphones, tablets, electronic books, pocket music players, wireless headphones or some cameras. The advantage is the ability to charge anytime and anywhere. You can recharge the discharged power bank from the electrical socket with a classic USB charger, the one you got for your smartphone.

Which one to choose?

We tested 14 powerbanks for capacity

We tested 14 powerbanks with a capacity of 2500 mAh and 20000 mAh.

When selecting a power bank, it is necessary to include several (sometimes conflicting) properties and parameters. The keys are capacity, maximum input current and weight of the power bank.

Capacity is a property that indicates the amount of energy that the power bank is able to store.

The smallest capacity of around 2,600 mAh is usually not enough for a single fully charged smartphone, they are the smallest and lightest and as a last resort they can be handcuffed. At the other end of the menu, we find powerbanks with a capacity of 30,000 mAh (sometimes even more), which are sometimes adapted for powered laptops or emergency starting vehicles. They are bag-sized and usually weigh more than a pound of weight for everyday use in the event of accidents. Therefore, we did not include them in the test.

The best-selling today are powerbanks with capacities of around 10,000 mAh. You have about a hundred or two to charge a discharged smartphone, but of course badly for the size of the battery in the phone and I will discharge it. At the same time, they have a fine weight in the range of 200 – 250 grams.

As follows from the previous dk, with increasing capacity usually increases i mass powerbanks. In most cases, these consist of non-woven Li-Ion batteries (often type 18650 with a voltage of 3.7 V and a capacity of 2,200 – 2,600 mAh) and the growing capacity of the power bank thus requires a number of pouitch lnk.


Disassembled batterypack (TP-Link 5200 – not in test). The base is two Li-Ion batteries 3.7V, 2600 mAh from LG Chem. On the right you can see me and dc and charge electronics.

Just for the sake of interest, you can find practically the same links in notebooks, e-bikes, batteries or electric cars.

He gave an important feature that needs to be taken into account when choosing a power bank maximln proud, which has a USB input. It determines whether the connected device will be able to charge the maximum speed, or it will take according to, it is not necessary. If you want a reasonable speed to charge a modern smartphone or tablet, it should have an input of at least 2 A, if it is able to supply more (eg 2.4 A or 3 A), that’s it. You don’t have to worry about your phone or tablet, the electronics of the connected device will take care of that.

Fma around capacity

If you have ever tried to find advice on choosing the power bank on the Internet, you have probably come across the information that the manufacturers are lying, because the stated capacity is the sum of the capacities of individual lines and is valid for 3.7 V, not 5 V, which is at the input powerbanks by about 26% ni. This means that the 10,000 mAh power bank will have only 7,400 mAh at a 5 V voltage.

Mathematically, it fits, it’s true.


Disassembled surfaces of Li-Ion lnek. In the wolf-shaped area would be the wall of the rulic. // Warning: never attempt to disassemble lithium batteries yourself, risk of injury and damage.//

The reason is that most users will charge a device with a power bank, which themselves have batteries with a voltage of 3.7 V and for this voltage also the specified capacity. In this respect, the stated capacity of the power bank for 3.7 V is essentially relevant, because it is a value that can be compared with the devices that you will connect. In other words, you can compare 10,000 mAh to your phone’s 3,000 mAh battery – both at the same voltage.

So the salary is that with a 10,000mAh power bank I charge a 3,000mAh phone tikrt and go a little energy left? Unfortunately, it is not valid.

This comes into play, for example, which produces 5 V in the power bank from 3.7 V and then the type in the phone, which, in turn, produces 3.7 V from the input 5 V to charge the phone’s battery. The activity of the surface monitors is around 90% (although the test also dealt with the darkness), so the loss of energy only at the transmissions is around 19%.

To charge the 3,000 mAh battery in your phone, you need about 3,600 mAh of energy in the power bank.

How to treat powerbank?

Because the manufacturer does not specify the exact type (chemical compound) of the Li-Ion battery, nor even the details of battery management, ie the electronics that the battery is charged, we will respond with the same possibility – with links that can be charged to a significant decrease in capacity. about 400krt and electronics, which will try to get the most out of them (because vt values ​​sell).

To prolong the overall life of the power bank, it is advisable not to discharge it to zero, but ideally from two tenths, which indicator on the power bank allows you to estimate. And when you discharge it, do not leave it discharged for a long time, counsel Tom Reichl from the Faculty of Electrical Engineering at BUT, who specializes in battery diagnostics. And what is important, as soon as you charge it, let it charge and finish, Reichl adds.

It is a good idea to switch off the charge just before the end (this, on the other hand, may extend the life of the battery, but on the one hand it will reduce the currently available capacity and on the other hand it would require an inconvenient look for suitable time for disconnection). But for the battery, the harmful Peru is charged.

At the same time – and this also applies to smartphones, tablets and electronics – there is no problem leaving it plugged into the charger according to, it is not necessary. If it is not charged in the power bank (or smartphone, tablet, etc.) if it does not work properly, it will stop charging when the battery is fully charged and will not attempt to do so. In the case of both the phone and the tablet, the device is charged from the charger, the battery capacity does not decrease and it does not wear out in any way. At first, which recently took place in the tabloid press, that the non-charged phone and their batteries are untrue in the vast majority of modern cases.

As we tested

The value of the powerbank specified by the manufacturer cannot be verified otherwise. We therefore turned to the expert Pavel Hrzina from the Faculty of Electrical Engineering of the Czech University of Technology in Prague. He and his colleagues assembled a test system containing a small electronic network, a known medium for voltage and current, stabilized sources (were set to 5.1V / 3A) and performed a series test and related con:

  1. All samples were subsequently recorded and charged.
  2. A discharge test was performed to determine the capacity of the power bank.
  3. A test was performed to determine the speed charged by the power bank.
  4. A test was performed to determine the maximum current that the power bank is able to supply.
  5. The original cables were tested.

In some cases, especially those with a large difference between the stated and indicated capacities, the capacity test was performed twice. It should be noted that it always turned out essentially the same.


Mc to work in the laboratory of the Department of Electrotechnology, Faculty of Electrical Engineering, Czech University of Technology in Prague.

Metodika nabjen: Using a laboratory power supply, a charger with a USB input was simulated. The system did not use the method of negotiating the maximum current, it was simulated in general USB charger. Due to the absence of exact specifications of requirements for offers from the manufacturers of tested powerbanks, this method was chosen to ensure the same test conditions. It is not excluded that some power banks will be able to negotiate via the USB data wires in cooperation with one of the commercial chargers in the charging current. The power supplies used were able to provide 3A pi voltage at the 5.1V terminals. However, Vtina powerbank took only 0.8A 1.5 A from the source. This corresponds to the USB specification (Imax 1.5A). The cable supplied by the power bank manufacturer was always used when charging.

Methods vybjen (s same capacity): The powerbanks were discharged at a constant current by means of an electronic reader. The current was set according to the manufacturer’s specifications. If a current in less than 2 A was specified, a value of 2 A was used.

The resistance of the original USB cable: To change the resistance, one end of the original cable was short-circuited with the help of a microUSB connector, with the help of a modified microUSB connector, and a precise laboratory ohmmeter was then connected to the USB A connector. The result is the resistance value of the supply conductors, including the transient resistances of the USB A and the microUSB connector.

The results

The Xiaomi 20000 power bank had the largest intended (ie user-usable) capacity, for which we measured 12,044 mAh at 5 V. After switching to energy in watt-hours (where napt does not play a role), the manufacturer promises 74 Wh, the power bank offers 60.2 Wh – the difference is 18.65%.


Utilized by the manufacturer declared energy bank. Blue = actual usable capacity, orange = difference from the capacity declared by the manufacturer. 1) ADATA A10050, 2) Anker 10400, 3) Axagon 10000, 4) GoGen 2500, 5) GP 8400, 6) Platinet 5000 7) Platinet 13000, 8) Power Plus 16000, 9) Proda Remax 20000, 10) Samsung 10200 , 11) TP-Link 3350, 12) TP-Link 6700, 13) Xiaomi 5000, 14) Xiaomi 20000

As an absolute choice, we chose the Anker 10400 power bank. The reason for this choice is a high-quality current input (supply bank and 3.2A), high-quality design and pleasant dimensions with sufficient capacity. According to the manufacturer m powerbank to store 38.5 Wh of energy, we measured 32.3 Wh, which is a difference of 16.1%. The supplied cable was thus one of the better pieces and the package also includes a practical transport package or bag.

We will also evaluate the ADATA A10050, Axagon 10000 and Samsung 10200 power banks for a very long time.


Maximln vstupn proud powerbanky. Modr = hodnota udvan vrobce, oranov = hodnota namen. A = port1, B = port 2. 1) ADATA A10050, 2) Anker 10400, 3) Axagon 10000, 4) GoGen 2500, 5) GP 8400, 6) Platinet 5000 7) Platinet 13000, 8) Power Plus 16000, 9) Proda Remax 20000, 10) Samsung 10200, 11) TP-Link 3350, 12) TP-Link 6700, 13) Xiaomi 5000, 14) Xiaomi 20000

On the contrary, the PowerPlus 16000 power bank, which was not able to stably supply current at about 1.5 A, although the manufacturer of 2.1 A, was included among the failures. with some device code. Its actual capacity is 30.1% lower than the values ​​declared by the manufacturer (41.2 Wh vs. 59.2 Wh).

proper breeding of the Power Plus 16000 power bank when discharged – instead of turning off, it starts to vibrate.

proper breeding power bank TP-Link 3350 – after less than an hour at 1.2 A load turned off…

The TP-Link 3350 also turned out to be bad, as it was not able to stably supply even 1.5 A, after which it switched off at 1.2 A after hours, probably due to overheating. It thus offered a record disproportion between the manufacturer’s actual and actual energy supply – the city of 12.4 Wh will offer only 3.6 Wh, which is 70.7% less. At lower power (approx. 0.9 A), the TP-Link power bank was able to release the rest of the energy. That’s why you won’t charge modern phones. In both cases, we also provided the type of sample for the test and repeated the names – unfortunately this did not help their evaluation.

You can find all the results at the individual powerbanks in the photo gallery.

Problem jmnem kabel

The supplied USB cable became a somewhat surprising weakness of some powerbanks. This was because it was often so undersized that it was able to lose 0.4 V at a current flow of 2 A at a voltage of 5 V. This loss (0.8 W) was expected to be in the form of heat. It is possible that poor quality handbags are able to lose about 5 – 10% of energy.

Resistance leads

The resistance of the supplied cable leads. Here, on the contrary, it is true that its value is better. 1) ADATA A10050, 2) Anker 10400, 3) Axagon 10000, 4) GoGen 2500, 5) GP 8400, 6) Platinet 5000 7) Platinet 13000, 8) Power Plus 16000, 9) Proda Remax 20000, 10) Samsung 10200 , 11) TP-Link 3350, 12) TP-Link 6700, 13) Xiaomi 5000, 14) Xiaomi 20000

The result is a slow recharge of the power bank or connected to the power bank of the connected device. In such a situation, the energy stored in the power bank is left full.

Thanks to the power bank Anker, Axagon, GoGen, GP, Platinet, PowerPlus and Proda for the test, we thank the Alza.cz store. Powerbanks Xiaomi drank shop XiaomiMobile.cz. Powerbanks ADATA and Samsung were included in the test by the official esk represented by the company.

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