I'm looking to power a rPi Zero W and a tomoko 87 mechanical keyboard both of which take 5v power (I know the rPi needs 1amp, not sure about the tomoko 87 as the description simply says "5v DC"). I'm thinking of using the Powerboost 1000 charger/recharger from adafruit and a Lithium Ion Polymer Battery - 3.7v 2500mAh to power them. Do I need to use 2 batteries? Or must I use 2 Powerboosts? Or do I need to use two batteries and two Powerboosts?