What do you think about the idea of ​​using the powerbank as an uninterruptible power supply for Raspberry Pi (or other electronics)?

Question

Electronics

Good afternoon!
I would like to discuss the idea of ​​using a powerbank as an uninterruptible power supply and express my concerns.
I encountered some unpleasant moments, which I will write about later.
There was a problem when it is necessary to provide uninterrupted power to Raspberry Pi 3.
Characteristics of the original power supply: 5V 2.5A.
In practice, I looked, I have a consumption of about 1-1.5 Amperes (but the board is not fully loaded, WiFi is not used), because I suspect that the consumption may increase further.
I am advised to use Powerbank as an uninterruptible power supply.
However, when I initially considered the idea of ​​an uninterruptible power supply and selected what could be used as a source of this power, I had some concerns about Powerbanks.
Before that, I came across 12V uninterruptible power supplies and there I encountered one unpleasant situation - a mismatch between the declared parameters and the real ones.
In particular, it was a guaranteed output current at a certain voltage.
And the essence of the problem was as follows:
- we have a certain current at the input of the uninterruptible power supply,
- in the case of a charged battery, the input stabilizer normally works on the output and provides the required current,
- however, at a certain point in time, a situation arises when the input power is turned off, the system switches to battery power, working from the battery for some time,
- I do not yet consider issues related to what current the battery gives, at what current the protection is triggered (in lithium -polymer batteries), etc.,
- however, when the input power reappears, the current that the input stabilizer gives off branches and part of the current goes to charge the battery,
- and here I was faced with a situation where the output current ceased to correspond to the declared parameters, t .to. when I ate to select the declared and necessary current for me, the voltage sagged due to the fact that the input stabilizer simply could not normally provide the total current per battery charge and the current at the output.
Now back to Powerbank.
I decided to conduct an experiment and test my fears.
For experiments, I took the available Xiaomi Mi Power Bank 2 5000.
When a phone is connected to it (with the input voltage turned off), the USB parameters are as follows: 4.97-5.1V 0.9-1.2A.
However, as soon as I turn on the input voltage, it happens
- firstly, a sharp drop in the output voltage to 4.73-4.75V and a current drop to 0.4-0.5A,
- secondly, when the powerbank input power is turned off after that in 30-40% of cases first turned off the output power at all, and then turned back on the original parameters 4.97-5.1V 0.9-1.2A.
Based on this, I personally concluded that the manufacturer did not consider the option that it can be used as a UPS, because otherwise he would have provided
- firstly, another option for switching power supply from the battery / from the mains, which would allow to avoid power failures / power outages during switching,
- secondly, it would provide more or less matching of the output parameters in cases of power supply from the battery / from the mains.
But again, all this was tested on only one available powerbank, perhaps some other powerbank manufacturer will behave differently.
If so, I would be happy to find out what kind of manufacturer it is and would buy it for myself to try.

Answer 1

I have an old PB Hiper MP12500. It pulls out the third raspberry and does not cut the output power when an external power supply is connected, but it is cut down when the charging is turned off. In this case, the power supply to the ports is turned on only by a button on the case.
There is a newfangled Romoss SW20 Pro 20000 mAh with automatic power on and fast charging. When the external power is turned on, it briefly cuts the outputs, so that the raspberry goes into reboot.
Low voltage messages periodically appear on both.
UPD : There are still such things. Claimed to function as UPS
https://geekworm.com/collections/raspberry-pi-4/pr...
https://geekworm.com/collections/raspberry-pi-4/pr...

Answer 2

On Aliexpress, there are shields for the battery with a controller for i2c batteries with a high current output, just take it or something.
#Aliexpress $1,140.47 10% DISCOUNT | New UPS Power Device Extended Two USBA Ports for Raspberry Pi 4 B/3B+/3B, compatible with 18650 battery (not included)
https://a.aliexpress.ru/_Nq7I8

Answer 3

I bought a power bank with the UPS function on Alik. Called Soshine E3S, copes with the declared functions.

Answer 4

This is a normal situation, usually the power bank controller can either charge the internal battery or discharge it, not at the same time.
When the battery is discharged - all the current goes to your device.
When the battery is charging - charging is due to the current of the power supply, power to your device is also due to this power supply. Perhaps the power supply does not pull out both the battery and your device.
As already said, you need a power bank in which the ability to work as a UPS is directly registered
. Or a special 5 volt UPS like this https://www.aliexpress.com/item/4000321440982.html