USB-A
The total number of
USB-A ports for charging connected gadgets. This type is gradually being replaced by USB type C, however, most models still use USB-A as the main output. This is also indicated by the number of corresponding ports. Classic are
2 USB-A outputs. However, there are also compact
models for 1 output, and more impressive ones with
3 and
4 USB-A(even more).
Max. power (per 1 port)
The maximum power that the power bank, theoretically, is capable of delivering to one rechargeable device. Usually, this power is achieved under the condition that no other device is connected to the battery (although exceptions to this rule are possible). And if you have ports with different charging currents or support multiple fast charging technologies, this information is given for the most powerful output or technology.
For modern power banks, a power of
10 watts or less is considered quite low; among other things, it usually means that the device does not support fast charging. Nevertheless, such devices are inexpensive and often turn out to be quite sufficient for simple tasks; Therefore, there are many models with similar specs on the market. The power of
12 – 15 W is also relatively small,
18 W can be called the average level,
20 – 25 W and
30 – 50 W is already considered an advanced level and in some solutions this parameter may
exceed 60 W.
In general, higher power output has a positive effect on charging speed, but in fact there are a number of nuances associated with this parameter. Firstly, not only the power bank, but also the gadget being charged should support the appropriate power — otherwise the speed of the process will be limited
...by the specs of the gadget. Secondly, in order to use the full capabilities of the power bank, it may be necessary for it to be compatible with certain fast charging technologies (see "Fast Charging").USB type С
USB type C is a popular type of USB connector characterized by its small size, reversible design, and fairly advanced (in theory) capabilities. If there are several connectors of this type, the first one is considered to be capable of delivering more power.
It is characterized by the rated power supplied by the power bank when a load is connected to the first or only
USB type C output and the current strength. The speed of the charging process directly depends on the power. It is traditionally calculated by multiplying the current by the voltage; However, the standard voltage for USB power is 5 V, so current is considered to be the main indicator of power.
The magnitude of the charging current directly determines the power supplied to the device being charged - and, accordingly, the maximum speed of the process (in practice, it may be lower if the device being charged has strict restrictions on the charge current). Power is also determined by the supply voltage (the number of watts is calculated by multiplying amperes by volts); While the standard USB output voltage is 5V, many fast charging technologies (see below) use higher voltages. Therefore, in the notes to this paragraph, the maximum power on the USB type C connector is also indicated.
As for specific values, the most popular option for USB type C outputs in modern power banks is
3 A. There are also other values - both sma
...ller ( 2.4 A, 2.1 A and 2 A) and larger ones - but noticeably less frequently.USB A
A standard
USB A port is characterized by the rated power supplied by the power bank when a load is connected to the first or only USB A output and the current strength. If there are several connectors of this type, the first one is considered to be capable of delivering more power.
The speed of the charging process directly depends on this indicator. Power is traditionally calculated by multiplying current by voltage; However, the standard voltage for USB power is 5 V, so current is considered to be the main indicator of power.
The charging power and, accordingly, the speed of the process depend on the current strength. Nowadays, on USB ports, a current of
2 A or
2.1 A is considered basic and quite modest,
2.4 A and
2.5 A are average,
3 A and
more are noticeably above average, and certain fast charging technologies allow you to achieve values of
4 A. 4.5 A and
5 A. However, it is worth considering that to operate at high current, such an opportunity must be provided not only in the power bank, but also in the gadget being charged. So when purchasing a model, it doesn’t hurt to check whether the devices being charged suppo
...rt high charge currents.
It is also worth noting two nuances associated with the presence of multiple USB charging ports. Firstly, they may differ in the current they produce. This allows you to select the optimal connector for each device: for example, to quickly charge a tablet with a capacious battery, it is desirable to have a higher current, and a device with a low charging current can be connected to a “weaker” port, so as not to create unnecessary load on the battery and controller. The second caveat is that if all USB connectors are used simultaneously, the current supplied by each of these connectors may be lower than the maximum; in other words, not all power banks allow you to simultaneously use USB ports at the maximum possible power. You can understand whether such a possibility exists by looking at the charge power (see below); if the charge power is not indicated, you should refer to detailed documentation from the manufacturer.USB A (2nd)
Characteristics of the second USB A port. Read more in the paragraph above.
Power bank charge current via USB
Nominal charge current supported by the power bank when charging its own battery via microUSB, USB type C, or Lightning (see "Battery charging inputs").
This is the maximum and, in fact, the recommended power bank charge current. If the amperes supplied by the power source exceed this value, the charge current will still be limited by the built-in controller to avoid overloading. And using a charger with a lower output current, in turn, will lead to an increase in charging time.
Data on the charge current via USB (Lightning) is especially important due to the fact that modern power banks are usually not equipped with their own chargers for these inputs, and energy sources must be separate. On the other hand, if a high charging speed is not critical for you, you can ignore this parameter: any USB connector is suitable as a power source for the corresponding power bank inputs.
Full charge time
The time required to fully charge a battery discharged “to zero”. Features of the charging process in different models may be different, respectively, and the time required for this may differ markedly even with the same capacity.
Fast-charging batteries tend to be more expensive. Therefore, choosing this option makes sense if you do not have much time to replenish your energy supply — for example, for hiking. However, keep in mind that charging at full speed may require a charger that supports certain fast charging technologies (see below).
It must also be said that in most modern batteries, the charging speed is uneven — it is highest at the several first percent from zero, then gradually decreases. Therefore, the time required to replenish the energy supply by a certain percentage will not be strictly proportional to the total claimed charge time; moreover, this time will depend on how much the battery is already charged at the time the procedure starts. For example, charging from 0 to 50% will take less time than from 50 to 100%, although both there and there we are talking about half the capacity.
Charge cycles
The number of charge-discharge cycles that the battery can withstand without significant loss of performance.
During operation, batteries wear out, and because of this, their specs (primarily capacity) noticeably deteriorate. Battery life is usually measured in charge-discharge cycles. The features of counting cycles are described in detail in special sources, but here we note that not always models with the same claimed resource turn out to be equally durable in fact. The fact is that different manufacturers may understand “significant loss of performance” differently: for example, one brand can indicate a resource up to a 20% decrease in capacity, the second — up to a 60% decrease. Therefore, when choosing, it makes sense to focus not only on pure numbers, but also on other sources — test results, reviews, etc.
Also note that battery life can be noticeably reduced if the operating conditions are violated — for example, in case of overheating or excessive cold.
Low current charging
Low current charging allows you to seamlessly charge devices that do not require high current. This allows you to extend the life cycle of the devices and protect them as much as possible during charging. Such devices include smartwatches, headphones, headsets, etc.
