kimberlina2278, do you know the exact model of the Anker battery pack for your backpack that automatically turns on when you plug it in your outside power port??? That would be very helpful! Thank you.
Our USB backpack fits most of Power Banks. There is a point is that most power banks require to push a button to power on. And you need to reach your backpack, then open your power bank and charge your phone.
So a power bank require no button push to power on will be more convenient.
The problem will most likely arise due to the diameter of the base of the water bottle. My bottle fits very snug into pockets and this is the thinnest bottle that I own with a diameter of 2.5 inches. Anything larger than that will probably not fit well.