Power Bank to Arduino

Is it possible to connect a power bank (5V) to arduino (between Vin and GND pins)? Should I take any precautions?

Enryke:
Is it possible to connect a power bank (5V) to arduino (between Vin and GND pins)?

It is possible but won't work as expected. The 5V regulator needs a 7V input to give a 5V output. If you connect 5V to the Vin pin (which leads to the input of the regulator) you will get less than 5V out. Perhaps as low as 3V which isn't enough to properly run a 16 MHz Arduino.

If you have regulated 5V for an input you should connect it to the "+5V" (post regulator) pin and not the "Vin" (pre regulator) pin. You could also connect it through a USB cable.

Interesting! so Vin leads to the input of the regulator AMS1117 like the jack input?

Enryke:
Interesting! so Vin leads to the input of the regulator AMS1117 like the jack input?

Yes. The only difference is that the power jack goes through a polarity protection diode first to avoid problems where the center pin is negative instead of positive.