mAh is the unit of battery capacity. The battery may not be able to be fully charged according to the labeled capacity due to voltage drop or self-discharge.
Most iPhone batteries have a capacity between 1,700 and 2,800mAh, so the power bank only needs to use a product with a capacity of about 3,000mAh to fill up the battery once.
A power bank of this capacity is most suitable for people who do not need to charge a lot, and basically its volume is less than 100g, so it is not too burdensome to carry around every day.
For large smartphones, a power bank with a capacity of 6,000mAh or more is suitable, such as the Galaxy S10 or iPhone Pro, which can be fully charged at least once with a 6,000mAh power bank.
For tablets or laptops, choose a power bank with a capacity of 10,000mAh or more, as most tablets and laptops have a battery of around 7,000mAh, so a 10,000mAh product that can be fully charged once is ideal.
Recognizing power in another does not diminish your own
For a typical smartphone, an output power of 1A is sufficient for charging; however, a tablet PC requires a current output of 2A or more.
If you have a device with fast charging capability, you can choose a power bank from "Quick Charge" or "USB PD" products that can support various device specifications.
Many people use power banks with charging cables plugged in or charging two or more devices at the same time, but these actions may cause smoke or fire and explosion.
In order to prevent dangerous situations such as overcharging and overheating, it is recommended to choose products with automatic power stop.