Zagg Dual USB Power Bank/Charger 12000mah £10.99 at 7dayshop

Complete with USB charge cable etc. Useful emergency back-up power for your mobile device – compatible with Apple iPhone, Samsung Galaxy, Motorola, LG, HTC, Sony, Nokia etc etc
Easy to use and carry – portable, compact and sleek design. Dimensions: 14x8x2.2cm – Use and then simply recharge over and over again. Offers twin USB charge and power ports, great for travel and commuting where you cant get to a power source.
High output 2.1A output for fast charging times. This unit also features a very useful built in LED torch! Extra high capacity of 12,000mAh – Enough power to charge most smartphones up to four times!
Built in short circuit protection. Airline safe – carry on as hand baggage. Allowed through airport security. USB Charging Cable included – use any USB port to re-charge this battery, that could be a computer, laptop or mains to USB adapter etc.