Hi everyone is there a way i can i monitor the battery percentage of my power bank connected in the Jack Barrel and flash it in the LCD screen? I just want to know the battery percentage of my power bank using only the screen display.
SparkFun LiPo Fuel Gauge, might be of interest to you.
And yes it is possible to tap the incoming.
What you want is a coulomb counter, they are very difficult to make and get accurate results. Battery chemistry has a big impact on this circuit.
Since you do not connect a 5 V "Power Bank" to the "barrel jack" of an Arduino (at least not on a UNO, Leonardo or Mega 2560), I find your question rather confusing.