see: DIYSchema
USB Charging Circuit
3V to 5V Generic DC to USB Booster
Lithium Charge Controller with 5V Out
Single USB Boost + Lithium Charge Controller Board
12V Solar Charge Controller Dual USB
PowerBoost 1000 Basic - 5V USB Boost @ 1000mA from 1.8V+
Lithium Ion Polymer Battery - 3.7v 2500mAh
uninterruptible power supply for P
http://www.pi-supply.com/product/pi-supply-raspberry-pi-power-switch/
5V
72W LAPTOP BATTERY
39W USB Battery
12V