Hi,
narri:
I have a proyect using an Arduino mega rev3, with an ultrasonic sensor and a RGB LED to indicate the distance(calculated with the sensor), it is powered with a verbatin Powerbank, which is conected to the ground and to a resistor in the PCB, to drain the energy, which is the same as conecting to the VIN
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
If you are using a 5V USB powerbank, you can connect it directly to the USB socket on the mega.
Thanks.. Tom.. 