Battery capacity
The higher the battery capacity, the more energy the power bank is able to accumulate and then transfer when charging to gadgets connected to it. But it should be borne in mind that not all of the accumulated energy goes specifically to charging – part of it is spent on service functions and inevitable losses in the process of transmission. So in the specifications, the real capacity of the power bank is also often specified. If there is no data on real capacity, then when calculating it is worth proceeding from the fact that it is usually somewhere 1.6 times lower than the nominal one. For example, for a model with a nominal capacity of 10,000 mAh, the actual value will be approximately 6300 mAh.
As for the specific values of the nominal capacity, then in models with the lowest performance it is
5000 – 7000 mAh and even
less ; such power banks are suitable as a backup source of energy for 1 – 2 smartphone charging with a not very capacious battery or other similar gadget. The
10,000 mAh solutions are the most popular nowadays – in many cases, this option provides the best price-capacity ratio. The
20,000 mAh and
30,000 mAh options are also very common. But even a capacity of
40,000 mAh or
more, thanks to the development of modern
...technology, is quite common.Real capacity
The real capacity of the power bank.
Real capacity is the amount of energy that a power bank is able to transfer to rechargeable gadgets. This amount is inevitably lower than the nominal capacity (see above) — most often by about 1.6 times (due to the fact that part of the energy goes to additional features and transmission losses). However, it is by real capacity that it is easiest to evaluate the actual capabilities of an external battery: for example, if this figure is 6500 mAh, this model is guaranteed to be enough for two full charges of a smartphone with a 3000 mAh battery and smartwatches for 250 mAh.
The capacity in this case is indicated for 5 V — the standard USB charging voltage. At the same time, the features of milliamp-hours as a unit of capacity are such that the actual amount of energy in the battery depends not only on the number of mAh, but also on the operating voltage. In fact, this means that when using fast charging technologies (see below) that involve increased voltage, the actual value of the actual capacity will differ from the claimed one (it will be lower). There are formulas and methods for calculating this value, they can be found in special sources.
Battery capacity
Battery capacity in watt-hour. These units of measurement are less popular than MilliAmp hour, but are more physically correct: they accurately describe the amount of energy accumulated by the battery. Thanks to this, in terms of capacity in Wh, it is possible to compare batteries with different rated voltages (while for mAh this is not allowed — additional calculations must be carried out using special formulas). At the same time, Wh can be converted to mAh without much difficulty if the battery voltage is known (for power banks this is in most cases 3.7 V): to do this, the capacity in Wh must be divided by the voltage and multiplied by 1000.
USB C
The total number of
USB type C ports for charging connected gadgets. By 2023, they have become very popular. However, power banks are equipped mainly with
one output port of the corresponding format.
Models with 2 USB type C outputs have not yet gained such popularity.
USB C (2nd)
Characteristics of the second USB C port. Read more in the paragraph above.
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.
Bundled cables (adapters)
Types of cables and/or adapters for charging external devices included in the power bank set.
The type of such cables is indicated by the plug used to connect to the gadget being charged; connection with the power bank itself is usually carried out through a standard USB A or USB type C output. We emphasize that in this case, we are talking about detachable cables/adapters; types of built-in charging cables are specified separately (if any — see below).
In general, this parameter allows you to evaluate the possibilities of a power bank available out of the box, without purchasing additional accessories. As for specific interfaces, most often external batteries nowadays are equipped with
microUSB,
USB type C and/or
Lightning cables/adapters; more specific connectors are extremely rare. Here are the features of the most popular options:
— microUSB. A connector that is extremely common in modern portable gadgets. It is inferior to the newer USB type-C in terms of convenience and several performance specs, but still has not lost popularity.
— USB type C. A relatively new standard for miniature USB connectors, used for charging both portable equipment and larger devices — in particular, some ultra-compact laptops. Physically, it differs from microUSB in a slightly larger size and a two-sided design that allows you to connect the plug b
...oth ways. In terms of performance, USB type C is notable for better compatibility with fast charging technologies (see above): more fast charging technologies can be used with it, and Power Delivery was created based on this connector. At the same time, the presence of a USB type C cable does not mean support for fast charging.
— Lightning. Standard original connector for Apple gadgets; other manufacturers do not have such a port.
Note that if several types of bundled cables/adapters are claimed in the specs, the specific format of such accessories may be different. For example, "microUSB plus USB type C" could mean two separate cables, one cable with two plugs, a cable with one plug plus an adapter to another, etc.
