Smartphone power banks are not designed for Raspberry pi UPS

[Michel]

Hello,

I recently discovered that some smartphone power banks have a neat pass-through charging feature. Not all of them have this feature!
"Pass-through" means that both power bank and smartphone can be charged at the same time (see red highlighted area in the picture below).
So why not testing "Raspberry pi - RasPBX" connected to the power bank ?

Unhappily as you will notice it hereafter, the Cellularline power bank is a useful device for mobile application but not suitable as UPS (Uninterruptible Power Supply) for a Raspberry pi running RasPBX permanently

Residual charge is displayed on the blue illuminated surface when pressing the power bank white button (see above picture)

I got some detailed informations from "Cellularline" support department:

1) A new Raspberry power supply is not needed as the "Cellularline power bank" maximum input current will be limited to 950 mA by hardware design. So existing Raspberry pi power supply may still be used. There is no need to buy a more powerful one.
2) As Raspberry pi consumption is approx. 700 mA, 250 mA will still be available for the power bank battery when using a 1000 mA @ 5V power supply ( in case RasPBX is running with only network cable connected -no USB device etc...- see picture below ).
3) Maximum "power bank" output current is 1000 mA. It suits Rasberry pi power requirements with above mentioned limitation (only network cable connected).
4) I am grateful to Cellularline support department as they honestly explained me that this power bank is not intended for applications where the power bank and consequently the battery stay permanently under power voltage.
Even if the support department didn't explained if battery has, or not, cut-off over-charge protection, the whole power bank keeps warm when running permanently. This may result in shorter battery life

All smartphone "power banks" have the same design. Battery and voltage regulator, PMIC (Power Management Integrated Circuit) or DC to DC converter are in the same enclosure. These components unhappily generate heat exchanged with the battery.

Nevertheless the small Raspberry installation below is operational for more than 3 hours with a full charged battery. It may be useful in some mobile applications.

The black HAMA mains power supply, seen on this picture, is not part of the package. It is my existing 1000 mA @ 5V Raspberry pi power supply with its micro USB connector plugged into the power bank.

This USB Pocket charger 2200 costs 30,24 EUR in Belgium (including 21% VAT)

Contents of the package:
1) Power bank
2) Micro USB - USB white charging cable
3) Instruction manual