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.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.
