How to choose a power bank: capacity, power, use case
- 2 days ago
- 7 min read
A power bank has long stopped being just an “emergency battery for your phone”. Today, it can be a compact 5000 mAh magnetic model for everyday top-ups, or a powerful 20,000-27,000 mAh battery with USB-C Power Delivery for a tablet or laptop, including USB PD 3.1 support and up to 140W. Even wireless charging has changed: Qi2 brought magnetic alignment and 15W, while the new Qi2 25W profile raised the bar even higher.
That is why capacity in mAh is an important parameter for a power bank, but not the decisive one. By itself, it does not answer the main question for modern devices: can this specific power bank charge your device quickly and correctly?
Where to start
First, it is worth answering one question: what exactly will you charge most often?
If it is only a smartphone, a compact 5000-10,000 mAh model is often enough. If you also carry a tablet, headphones, a watch, or want several days of autonomy during a trip, it makes more sense to look at 10,000-20,000 mAh. If the power bank is also needed for a laptop, the approach is completely different: not only capacity matters, but also the power from a single USB-C port, supported protocols, and a suitable cable.
Why capacity alone is not enough
For modern devices, three things are critical: maximum power, support for the required protocols, and how much power the power bank can deliver from one port.
This is especially important for laptops. In real life, the typical reference point for a universal USB-C power bank is usually in the range of 65-100W from a single port. This is usually enough for office laptops and ultrabooks, and sometimes also for more powerful models under light load. But there are exceptions. Apple officially uses a 140W USB-C power adapter for the 16-inch MacBook Pro, while gaming laptops often come with 280-330W power supplies. However, their USB-C charging may be limited to about 100W and may be suitable mainly for work, not for maximum performance or gaming.
This leads to a simple conclusion: a power bank can indeed be suitable for modern laptops, but it should be chosen not by the “for laptop” label, but by the real power of a single USB-C port and by the limitations of the laptop itself.
Why PPS is important for many smartphones
If you have a Samsung, Google Pixel, or a modern smartphone from one of the Chinese brands, looking only at “30W”, “45W”, or “65W” on the power bank box is not enough. PPS support is also important, and sometimes the specific PPS voltage range matters too.
Samsung shows this clearly even with its official accessories: the branded 45W adapter declares PD 3.0 PDO/PPS max 45W. Google directly says that Pixel phones can use any PPS adapter rated at 30W or higher, while regular PD adapters from 15W also work, but that is already a different level of compatibility. With Chinese brands, the situation is less uniform: for example, Xiaomi has official accessories with QC/PD/PPS support, while OnePlus directly states that some models and accessories work with PD/PPS, but specific smartphones may behave differently with third-party PPS chargers. In other words, you need to look not at the brand in general, but at the specification of the specific smartphone model and power bank.
That is why a good power bank today should be evaluated not only by maximum watts, but also by the list of supported protocols. For some users, PPS is not a bonus, but a mandatory requirement if they want truly fast charging, not just “charging via USB-C”.
USB-C cable matters!
Even the right power bank may fail to show its full potential if you use an unsuitable cable. This is especially important for laptops and any high-power charging modes.
A regular USB-C to USB-C cable without any markings is designed to transmit up to 60W of power with a current up to 3A. But to allow the power source to deliver more power, the cable must have a special e-marker chip that reports whether this cable can transmit 100W (20V5A) or 240W (48V5A).
However, some devices may require 5A cables even at relatively low power levels, for example, PPS at 45W, 10.5V5A. This is found in Samsung flagship smartphones.
That is why it makes sense to choose cables with 100W or 240W support, so the cable does not become the bottleneck when charging your devices.
What capacity to choose
When choosing, it is more useful to focus not on “the more, the better”, but on the use case:
5000-10,000 mAh - This is a pocket format for those who need a light energy reserve for the day. Such models are well-suited for one smartphone, headphones, a watch, and occasional top-ups on the go. This class includes many slim magnetic power banks with wireless charging. Weight is usually roughly in the range of 100 to 250 g, while power is most often 15-30W, although faster options also exist. For example, IINIU P50-E1 10000 45W.
The most common use case for power banks in this category is:
a travel companion when actively using navigation, the screen, and the camera, when the battery does not last the whole day;
supporting smartphones with a worn battery during the day.
10,000-20,000 mAh - This is the most universal segment. It suits most users who need more than one “emergency” recharge, but do not yet need a heavy battery for a laptop. In this class, you can often find basic 22.5W models, many 65W models, and even some 310W models.
A power bank in this category is an excellent format for:
backup power for smartphones, and also laptops if it is 20,000 mAh and over 65W;
long flights, train or bus travel, vacations, camping, or working outdoors;
a travel companion when actively using navigation, the screen, and the camera, when the battery does not last the whole day;
mobile professional work: demonstrations, training, sales, technical presentations;
powering a mobile router;
powering a PD soldering iron when there is no access to mains power.
Weight usually falls roughly in the range of 180-500 g, although the exact figure strongly depends on power and design. At the same time, modern 20,000 mAh models with 100W can already weigh less than 400 g, which is noticeably better than the old idea that a power bank of this class must necessarily be heavy.
25,000-27,000 mAh - This is already a very interesting class for those who need a power bank not only for a smartphone, but also for a laptop. This is where you often find truly powerful models with 100-140W from a single USB-C port and very fast recharging at the same power level. Pass-through charging is also often implemented. These characteristics, and especially the capacity, come at the cost of weight: a typical reference point for serious models here is already about 400-650 g. However, technology does not stand still, and new batteries with higher energy density are appearing, reducing weight. For example, the INIU Cougar P63-E1 25000 100W weighs only 400g.
A power bank in this category is an excellent format for:
powering laptops and other electronic devices during long flights, train or bus travel, vacations, camping, or working outdoors;
working in a coworking space, park, or cafe with limited access to power outlets;
use in hospitals, exhibitions, and long conferences;
field work: interviews, content creation, working with drones;
mobile professional work: demonstrations, training, sales, technical presentations;
powering a mobile router;
powering a PD soldering iron when there is no access to mains power;
backup power during unstable or intermittent electricity supply.
However, considering its weight, this is no longer the accessory you want to carry in your pocket all the time. An important nuance: for flights, you need to look not only at mAh, but also at Wh. Power banks in this category have a capacity of up to 100Wh, which is the limit for carry-on luggage under IATA rules. 100-160 Wh may be allowed with airline approval, but this is a risk, and power banks cannot be placed in checked luggage.
Over 30,000 mAh - This is no longer an “everyday power bank”, but rather a solution for expeditions, long trips, camping, filming, drones, cameras, multiple laptop recharges, or working far from a power outlet. Here, devices often become noticeably larger and heavier, and some models are effectively close in concept to mini power stations.
Wireless charging: useful, but not mandatory
A separate use case is a power bank with wireless charging. It is convenient if you want to simply attach your smartphone and avoid carrying a separate cable for short top-up sessions. But it is important to understand that wireless charging almost always loses to wired charging in both efficiency and speed.
If you specifically need a modern magnetic format, it is better to look for Qi2 compatibility. This standard brought magnetic alignment and 15W, while the new Qi2 25W version raises the power even higher. But even if a wireless function is present, charging via USB-C cable will often remain the main scenario, while wireless charging is an additional option for cases where convenience matters more than maximum speed and efficiency.
Charging the power bank and a device at the same time
Some power banks have a mode that allows the battery itself and a connected device to be charged at the same time. This is usually called pass-through charging. This feature can indeed be useful: for example, in a hotel, on a train, or at a desk when you want to use one charger and avoid reconnecting cables.
But it should not be treated as a constant use scenario. For a power bank, this is a more demanding operating mode, especially if it is used often and under high load. As a one-time or situational feature, it is convenient and makes sense. As a 24/7 operating mode, it is more questionable.
Conclusion
A good power bank is chosen not by a single mAh number, but by a combination of four parameters:
capacity;
power from a single USB-C port;
support for the required protocols;
weight and dimensions.
The simplest guideline is this:
For an everyday smartphone, 5000-10,000 mAh is usually enough.
For a universal city use case, 10,000-20,000 mAh is usually the best fit.
For a laptop and travel, the 25,000-27,000 mAh class is especially interesting.
The segment above 30,000 mAh should be chosen for specific heavy-duty tasks, and with flight restrictions in mind.
