Power banks with a maximum capacity of 5,000mAh are useful if you're mainly looking for a light power bank. These power banks are all relatively compact, so they easily fit in your bag or pocket. Keep in mind that a 5,000mAh capacity can't even charge some smartphones once. Due to voltage conversion and energy loss during charging, the actual capacity is approximately 3,400mAh. That is enough to charge most iPhone models, but not enough to fill the battery of a new Samsung smartphone. You can use these power banks mainly for smartphones with a small battery or for accessories, such as earbuds and headphones.