Never charge a power bank with another — here's why

Portable batteries save smartphones on busy days, but what do you do when the charge in the battery itself is melting away before your eyes? Connecting it to another power bank seems like an obvious solution, but in practice, such a "chain" is more expensive than it seems.

SlashGear writes about it.

Can one power bank be charged from another?

Some models have a clear division of ports: one only "accepts" current, the other gives it away. If your power source works this way, it is possible to charge it from another battery, but each conversion of voltage from 3.7 V in the case to 5 V at the output takes away part of the capacity. Even branded devices with "smart" control consume charge due to losses, so the sum of the declared capacities will not provide "double" the benefit. To minimize losses, it is worth choosing the same voltages, the shortest cable, and the output with the highest current, but the efficiency will still be noticeably lower than when charging the phone directly.

Due to such energy losses and additional load on the electronics, there is almost no point in "transferring" the charge. It is more rational to use each power bank separately: this way, you will save battery resources and get more actual milliampere-hours for your smartphone or other gadget.

How to choose a power bank for your needs

Power banks differ not only in shape and capacity. Standard models work like a regular USB charger and power the phone via a cable or wireless coil. If you need to power a laptop, mini-fridge, or field equipment, you will need a large "stationary" class battery: bulky, heavier than a car battery, but capable of keeping your equipment running for hours while camping or in the workshop.

In every situation, the right power bank is the difference between comfort and forced shutdown. Determine which devices you will charge most often and choose a model with enough power and the necessary connectors to stay connected and safe even during long trips.

As a reminder, power banks have long been indispensable for those who are often far from a power outlet. However, there are still fake devices on the market with significantly "exaggerated" specifications.