I once heard my friends said she bought a power bank which disappointed her. She tested it by charging her smartphone and found out that the capacity was not as high as 20,000mAh.
So, is the capacity of a 20,000mAh power bank as high as 20,000mAh?
Today, I would like you to know the consensus in the industry which is unknown to the general public and some knowledge about the power bank.
It is similar to the fact that you can only get a little over 50GB from 64GB memory cards; you can't get 128GB storage memory from 128GB smartphones.
It is a kind of consensus in the industry. Those who do not know it think that they are fooled. You won't complain as long as you know something about it.
The available power banks have two capacities:
1. Battery cell capacity.
2. Rated capacity.
The 20,000mAh in the advertisements are about the battery cell capacity. What can be used is the rated capacity. There is no doubt that the rated capacity is lower than the battery cell capacity. The difference is enormous, far beyond 100mAh or 200mAh.
For example, the actual output capacity (rated capacity) of a Merpower 20,000mAh power bank is only 13000mAh.
The difference is 7000mAh. Don't the manufacturers fool us?
Of course not. Many factors lead to the difference, among which the most important is the conversion rate.
As for most power banks, the voltage of each battery cell is 3.7V. When charging a smartphone, the battery voltage should be increased to 5V, so the conversion rate is only 3.7/5=74%. In addition to other kinds of power consumption, such as the wires and the battery cells, only around 6,000mAh can be used out of 10,000mAh.
If you can find the capacity on the product, you won't think that you're fooled.
However, the main problem is, due to considerable consumption, most manufacturers only advertise the battery cell capacity of 20,000mAh, without mentioning the rated capacity.
That's the reason why many people don't think the capacity of their power banks is as high as 20,000mAh, and it is the manufacturers to blame.
Of course, we can't rule out that quite a few unbranded power banks are falsely tagged. For instance, a 10000mAh one is tagged 20000mAh. It is recommended that you buy a power bank from famous brands like Merpower & Anker to avoid being fooled.