Comparison Xiaomi Mi Power Bank 20000 vs Proda Power Box PPL-12

The type of own batteries installed in the power bank. Lithium-ion(Li-Ion) or lithium-polymer(Li-Pol) batteries are most commonly used today. Other options are less common — solutions based on nickel-metal hydride(Ni-Mh) batteries, as well as on LiFePO4 type cells. In addition, a rather promising development has appeared relatively recently — graphene batteries; however, as of early 2021, they are just beginning to be introduced into mass production. Here are the main features of each of these varieties:

— Li-Ion. Lithium-ion technology allows you to create quite capacious batteries of small dimensions and weight. In addition, such elements are easy to use (the main operating parameters are regulated by the built-in controller), have a high charge speed and are practically not affected by the "memory effect" (reduction in capacity when charging an incompletely discharged battery). The main disadvantage of lithium-ion batteries is a rather narrow range of permissible ambient temperatures. This is not a problem in urban usage, when the power bank is used mainly indoors and is carried in a pocket or in a bag; but for less favorable conditions (such as long hikes in the cold season), it is worth choosing models with good thermal insulation. You can also find information that lithium-ion batteries are prone to fires and even explosions; however, this is usually due to...failures in the embedded controllers, and these controllers are also constantly being improved, and nowadays the risk of such an accident is so low that it can actually be neglected.

— Li-pol. Further development and improvement of the lithium-ion technology described above; the main difference is the use of a solid polymer electrolyte instead of a liquid one (hence the name). This made it possible to achieve even greater capacity without increasing the dimensions, as well as to reduce the potential for fires and explosions during abnormal operation. On the other hand, lithium-polymer batteries are somewhat more expensive than lithium-ion batteries and are even more sensitive to temperature disturbances.

— Ni-Mh. Nickel-metal hydride batteries are distinguished by their reliability and a wide range of permissible temperatures, however, with the same dimensions, they are inferior in capacity to lithium-ion (and even more to lithium-polymer) batteries, and they also require certain specific operating rules to be observed. In addition, it is worth noting that Ni-Mh technology is well suited for removable batteries. It is in this format that such batteries are most often used: power banks of the Ni-Mh format are usually adapters with slots for several replaceable elements of a standard size (for example, AA). In this case, usually, several corresponding removable batteries are included in the kit, however, if desired, they can be replaced with other elements — these can even be disposable batteries from the nearest store. Such an opportunity can turn out to be very useful if the power bank is out of juice at an unfortunate moment, but there is no way to charge it; in addition, worn-out batteries can be replaced with fresh ones without changing the entire device.

— Li-FePO4. Another modified version of the Li-Ion batteries described above, the so-called "lithium iron phosphate". The advantages of such cells over classical lithium-ion ones are, first of all, a stable discharge voltage (until the energy is exhausted), high peak power, long service life, resistance to low temperatures, stability and safety. In addition, due to the use of iron instead of cobalt, such batteries are also safer to manufacture and easier to dispose of. At the same time, they are noticeably inferior to the classic lithium-ion ones in terms of capacity, and they are more expensive, which is why they are rarely used.

— Graphene. Batteries based on graphene — a carbon film one atom thick. The battery itself consists of a set of such films, between which silicon plates are laid, and lithium cobaltate or magnesium oxide is used as an anode. This design provides a number of advantages over the earlier batteries described above. First, graphene technology provides a high charge density, which allows you to create capacious and at the same time light and compact batteries. Secondly, for the production of such batteries, fewer rare resources are needed than for the same lithium ones; and the production itself is more environmentally friendly. Thirdly, such batteries are not prone to overheating and explosions when overloaded or damaged. On the other hand, graphene power supplies take a long time to charge and are not durable. However, this technology is still developing, and in the future it is likely that these shortcomings will be eliminated — completely or at least partially.

The total charge power provided by the power bank on all connectors overnight - when devices are connected simultaneously to all charging ports.

This parameter is given due to the fact that the total charge power does not always correspond to the sum of the maximum powers of all available ports. The built-in battery of a power bank often has its own limitation on the output power. Therefore, for example, in a model with two 18 W USB ports, each total charge power can be the same 18 W. Note that the distribution of power among the connectors may be different: in some models it is divided equally, in others it is divided in proportion to the maximum current strength (if it differs on different ports). These nuances should be clarified using the detailed characteristics of the charging connectors.

If you plan to regularly use all power bank connectors at once, you should pay attention to this indicator.

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.

The power in watts at which the power bank is charged under normal conditions.

The higher the charging power, the less time it takes to charge (given the same battery capacity). For example, fast charging of a power bank typically means a charging power of 30W or more. However, this parameter does not directly affect compatibility with charging devices: modern portable batteries can work with chargers of both higher and lower power. In the first case, the battery controller will automatically limit the charging current, while in the second case, charging will simply take more 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.

Fast charging technologies supported by the power bank. This is primarily about charging external gadgets, but the same technology can also be used when replenishing the power bank itself.

The fast charging feature, hence the name, can significantly reduce the time spent on the procedure. This is achieved through increased current and/or voltage, as well as smart process control (at each stage, the current and voltage correspond to the optimal parameters).

Fast charging is especially important for devices with high-capacity batteries that take a long time to charge normally. However, to fully use this feature, the power source and the gadget being charged must support the same charging technology; at the same time, different technologies are not compatible with each other, although occasionally there are exceptions. The most popular fast charging formats these days are QuickCharge (versions 3.0, 4.0 and 4.0+), Power Delivery (Power Delivery 3.0 and Power Delivery 3.1), Pump Express, Samsung Adaptive Fast Charging, Huawei Fast Charge Protocol, Huawei SuperCharge Protocol..., OPPO VOOC, OnePlus Dash Charge ; Here are the specific features of these, as well as some other options:

— Quick Charge (1.0, 2.0, 3.0, 4.0, 5.0). Technology created by Qualcomm and used in gadgets with Qualcomm CPUs. The later the version, the more advanced the technology: for example, Quick Charge 2.0 has 3 fixed voltage options, and version 3.0 has a smooth adjustment in the range from 3.6 to 20 V. Most often, gadgets with a newer version of Quick Charge are also compatible with older devices for charging, but for full use, an exact match in versions is desirable.
Also note that certain versions of Quick Charge have become the basis for some other technologies. However, again, the mutual compatibility of chargers/power banks and gadgets supporting these technologies needs to be clarified separately.

— Pump Express. Own development of MediaTek, used in portable devices with CPUs of this brand. Also available in several versions, with improvements and additions as it develops.

— Power delivery. Native fast charging technology for the USB type C connector. Used by many brands, found mainly in chargers (including power banks) and gadgets using this type of connector. Presented in several versions.

— Samsung Adaptive Fast Charging. Samsung's proprietary fast charging technology. It has been used without any changes since 2015, in light of which it looks quite modest compared to newer standards. Nevertheless, it is able to provide good speed, especially in the first 50% of the charge.

— Huawei FastCharge Protocol. One of Huawei's proprietary technologies. Formally similar to Quick Charge 2.0, but used with both Qualcomm and other brands of mobile processors, so compatibility is not guaranteed. In general, it is considered obsolete, gradually being replaced by more advanced standards like the SuperCharge Protocol.

— Huawei SuperCharge Protocol. Another proprietary technology from Huawei introduced in 2016; for 2021 is available in several versions. In some devices, the power of such charging exceeds 60 V — not a record, but quite an indicator.

— Oppo VOOC. OPPO technology, used both in branded smartphones and in equipment from other brands. Available in several versions; The latest (for 2021) version of SuperVOOC is for 2-cell batteries and is sometimes listed as a separate technology called Oppo SuperVOOC Flash Charge.

— OnePlus Dash Charge. A relatively old proprietary standard from OnePlus. An interesting feature is that in some gadgets, the effectiveness of Dash Charge is practically independent of the use of the screen: when the display is on, the battery charges at almost the same rate as when it is off. Technically a licensed version of OPPO's VOOC, however, these technologies are not compatible. Since 2018, Dash Charge has been phased out by Warp Charge, but this newer technology is still rare in separately sold chargers and power banks.

— PowerIQ. Technology developed by the Anker brand. The key feature of PowerIQ is that it is not a standalone standard, but a combined format of operation that combines a wide range of popular fast charging formats. In particular, version 3.0 claims the ability to work with Quick Charge, Power Delivery, Apple Fast Charging, Samsung Adaptive Fast Charging and others.

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.