Uninterruptible power supply for Raspberry Pi?

Question

Raspberry Pi

I don’t want to use 12 volt batteries and all sorts of boards for 2k+, I heard that there are PowerBanks that can recharge the battery itself and power the device at the output, and when the external power is turned off, continue to power the raspberry from the battery. But what I came across in my hands - requires turning on the button and at the same time either charging or feeding. At home I have a small cluster of 4 raspberries and one banana pi with a sata output, a backup Internet via a modem, it is very important to reserve not only the Internet, but also food, because. it happened - they cut down the Internet and I could not get access to important information.

Answer 1

what is the maximum consumption of the entire structure? lithium charger option - lithium battery - step-up / step-down converter for the desired current. from the power banks that the eloop e14 tested, it works on the output with the charging connected (powers xiaomi Wi-Fi nano + minicomputer on the atom).