Use promo code 5PLFWTKU to get the very well reviewed RAVPower Dynamo-On-the-Go RP-PB09 7800mAh External Backup Battery Pack down to $24.99. It'll provide spare power to your iPhone 5, iPad, Glaxy S4 and any other power-hungry USB gadgets. Over 100 reviews give it a 4.5 star average, so don't expect disappointment.