I have another issue with the battery charger, I don't know why but in order to output tension it needs to be plugged to the main power supply (220v AC) so that it leaves the "stand by" mode. Is there any way to bypass this? Or how can I simulate this behavior without doing so? I'll leave a picture of the controller too.
The big component marked 2R2 is an inductor. That's a tell tale sign of a boost (or buck) converter. This allows the power bank to output higher voltage (or more current in case of a buckconverter) than the batteries are able to provide.
Boost converters work by shorting the inductor to ground and then using the stored energy to boost the voltage.
Most power banks using such a boost circuit will have a sensing circuit to turn it off if there is no load.
The simplest method of keeping the circuit enabled is by adding more load to increase the current.
Nano operates at 5v, but its required input voltage is 7-12v, because there is a 5v regulator in the nano board, and this 2v gap is required to make the onboard regulator work.
But if you're feeding only 5v to Nano Vin, the Nano's regulator will not output the 5v required and that's the reason the Nano is not working. If the Nano doesn't leak any current, the power-bank regulator shuts down its output.
You could either:
- adjust your regulator to feed 7v to Nano's Vin; or
- feed the 5v from your power bank directly to the Nano 5V pin (this second option bypass the onboard regulator).
If you power-bank regulator has only an USB output (5v), there's only the second alternative.