Im using an Anker 13,000 mAh. It has a 1amp and a 2amp output (2 usb ports) I run the 1amp for the pineapple and the 2amp to power the usb hub, usb stick, alfa card and what ever else i need (like an android phone)
Although i need another battery, my phone has an extended battery (8000mAh) and requires 2amps to charge so with the usb drive plugged into the hub it sometimes doesnt recognize im connected and android tethering fails. A standard galaxy s3 would work perfect though