I want to purchase a USB Power Bank, one of the tiny portable ones, to power my Pi Zero, I need it to last at least 12 hours, but preferably 15 hours, for a comfortable safety cushion of time. My Pi would not be using WiFi and would only be using a USB sound card and a USB camera. The processor would be at 75-100% almost all the time. This link shows the power consumption of the Pi Zero, which at max is 800mA. So what size power bank would I need to purchase?
For power saving tips: Have a look @ Raspberry Pi Zero - Conserve power and reduce draw to 30mA http://www.midwesternmac.com/blogs/jeff-geerling/raspberry-pi-zero-conserve-energy