This is a common enough theme and there are some work arounds which may help see: Powering the arduino nano with a Power bank but also Google for Arduino Power Bank.
The long duration you have experienced is, as already pointed out, unusual.
This is a common enough theme and there are some work arounds which may help see: Powering the arduino nano with a Power bank but also Google for Arduino Power Bank.
The long duration you have experienced is, as already pointed out, unusual.