To choose the power of a power bank, first you have to know
for what type of use or device you need to charge. The
greater the storage capacity of your device's internal battery, the
greater the capacity of the external charger will have to be. Thus,
you can choose powerbanks from 1200 mAh to 3000 mAh that will be
perfect for backup charging or more powerful mobile chargers
ranging from 4000 mAh to 6000 mAh, ideal for powering a tablet.
Choose high capacity power banks of 10,000mAh, 15,000mAh or
20,000mAh for portable electronic devices, such as a computer.