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.
Power bank charging inputs
The type of input used to charge the power bank's own battery. Simply put, this paragraph indicates which connector on the cable you need to charge the power bank. At the same time, some models provide several inputs for charging at once, which simplifies the search for a cable. Also note that for models with a built-in power bank charging connector (see below), the type of this connector is specified separately.
Most often in modern power banks there are standard connectors
microUSB,
USB type C and/or
Apple Lightning. A lot of accessories are produced for such connectors — cables, network and car chargers, adapters, etc.; so there is usually no difficulty in finding a source of energy. Less common are models with
DC input, they are usually equipped with their own power supply (or at least a cable under such a connector). Here is a more detailed description of the different types of inputs:
— microUSB. A smaller version of the USB connector, still very popular in portable tech, despite the active spread of the more advanced USB type C. It has relatively modest capabilities — in particular, it does not allow the implementation of some advanced fast charging technologies. On the other hand, it is very easy to find a source of energy for such a connector: both modern and many of the frankly outdated cables and chargers are
...suitable for it.
— USB type C. A miniature type of USB connector, positioned, among other things, as the successor to microUSB. The most noticeable improvement is the reversible design, which allows you not to worry about which side of the plug is inserted into the connector. However, in the case of power banks, this is not the only or even the main advantage: USB type C has more extensive capabilities, allows more powerful currents and use a wider range of fast charging technologies (and Power Delivery was originally created specifically for this connector). Note that in some models the same connector of this type can be used both as an input for charging the battery and as an output for charging external devices — moreover, with automatic switching between these modes.
— Apple Lightning. Initially, this connector is designed for portable gadgets made by Apple. However, in the case of power banks, it can also be found in third-party devices: the idea is that the presence of Lightning allows you to charge an external battery using a cable from an iPhone or iPad and eliminates the need to look for a separate wire. For a number of reasons, this charging input is rarely used as the only one, more often it is provided in addition to microUSB or USB type C (see above).
— DC input. DC is a standard covering several types of connectors at once. Their common feature is a signature round shape, but the diameter, rated voltage and power can be different. In this sense, such connectors are not as convenient as USB type C, Lightning and other generally accepted standards — with a DC socket, it is best to use a native power supply (usually it comes bundled right away), and finding a third-party power source can be a problem. On the other hand, inputs of this type have practically no power limitations, it is easier to achieve high power supply with them than with the connectors described above. Therefore, DC inputs are used mainly in high-capacity power banks, where charging through a "weaker" interface would take an unreasonably long time. However, such models can also be equipped with standard microUSB or USB type C connectors "just in case".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.
DC power bank charge current
Nominal charge current supported by the power bank when charging its own battery via the DC connector (see "Battery Charging Inputs").
Models with DC charging inputs are usually equipped with chargers that most often have a current of this indicator. Therefore, you have to pay attention to the amperes indicated for the DC input, mainly when looking for a third-party charger for this connector. And here it is worth proceeding from the fact that the current issued by this charger should perfectly correspond to the charge current of the power bank itself. It is quite possible that the output current of the charger is lower than the nominal one — unless the charge time increases accordingly. But it is undesirable to connect a power bank to an overly powerful energy source: it is not a fact that the built-in controller can effectively reduce the current to the nominal value and prevent battery overload.
Laptop charging port (DC)
The ability to use a power bank to
charge laptops. Laptop batteries have a higher capacity and generally higher operating voltage than smartphone and tablet batteries; therefore, not every power bank is suitable for charging them. And even if such a feature is directly stated, the compatibility of a power bank with a specific laptop must be clarified separately: different laptop models can differ markedly in terms of battery charging parameters.
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.Features
Additional functions and features provided in the design of the power bank. Such features may include, but are not limited to,
an info display, a
USB hub mode, a photocell for
solar charging, a lighting source (
flashlight or
lamp), and a
shock -resistant body. Here's a more detailed description of each of these options:
— Info display. Own display installed on the power bank body. As a rule, it has a simple LCD matrix capable of displaying 2 - 3 characters and, in some cases, individual special icons. However, even such a screen provides a lot of additional information, makes it easier to manage the power bank and monitor its status.
— USB hub. Possibility of working as a USB hub (splitter). In this mode, the external battery’s own USB connectors act as USB inputs of a PC or laptop to which the power bank is connected. The connection itself, as a rule, is also carried out using the USB standard, and the battery can be charged. This function is convenient primarily because it allows you to use one USB port simultaneously to charge the power bank and connect a peripheral device (or even several). However, it does not hurt to make sure that the power supply of this port is sufficient to provide all these functions; and the charging speed may be quite slo
...w. If the power bank is fully charged, it can also be useful as a classic USB hub: to increase the number of ports available for connecting peripherals, and also as a kind of remote USB extension cable (for example, if there is a free USB port only on the rear panel of the system unit, which is difficult to get to).
- Flashlight. In this case, a flashlight means a built-in light source of relatively low power, usually directional (as opposed to the lamp described below). Such a source performs an auxiliary function; it can be useful, for example, for illuminating the road at night, for short-term illumination in a dark room (basement, cellar), etc.
- Lamp. Built-in light source, usually in the form of an oblong panel of several LEDs; such a panel can be made folding. Unlike flashlights (see above), lamps provide not directional, but diffused light, which has a shorter range, but covers a larger space. Such lighting can be useful, for example, for reading, for illuminating a room during a power outage, and even for creating a certain atmosphere.
- Shock protection. Enhanced protection against impacts and shocks. The specific degree of such protection may vary; it should be clarified according to the official characteristics; however, most models in this category are capable of at least transferring a fall from a height of about 1 - 1.2 m onto a flat hard surface without consequences. Well, in any case, such devices will be more resistant to mechanical stress than conventional ones. It is also worth noting that shock protection in modern power banks is most often combined with protection from dust and moisture (see above), although there are exceptions to this rule.
— Charging from the sun. Possibility of charging the power bank from the sun or other bright light source. To do this, a corresponding device is installed in the body - a solar battery (photocell). This function can be especially useful during a long stay away from civilization - for example, on a hike. And although the efficiency of solar panels in general is not very high, when exposed to bright light for a long time, you can accumulate quite a lot of energy.