ASCII art to show sizes is completely useless. How do you know what size monitor I'm using and at what resolution ?

If you don't even know the basics like what CAPACITY (mAh) pack you're using your guess will be as good as mine. Could 10 minute, could be an hour or more.

What you're doing is the equivalent of asking how far a car will go on a tank of petrol when you don't know either how much petrol the tank holds or how much petrol the car uses per mile. Sorry, can't help.

Steve