External batteries are always important and you can never really have enough. This I learned when the power went out a few weeks ago, and we were without power for a few days. Having 2-3 battery packs really helped me get through that time as I was still able to get some work done and not be completely bored during that time. But that's not the only reason to pick up a few battery packs. It's also great for when you're on the road, or on a camping trip, etc. Anker's Astro E4 13,000mAh battery pack is on sale today for $29.99. Which is actually a fantastic price.
Anker® 2nd Gen Astro E4 13000mAh External Battery Portable Dual USB Charger Power Bank. PowerIQâ„¢ Broad Compatibility, Fast Charging, High Capacity, Ultra Compact. For iPhone 5S 5C 5 4S, iPad Air mini, Galaxy S5 S4 S3, Note 3 2, Tab 4 3 2 Pro, Nexus, HTC One, One 2 (M8), LG G3, Nexus, MOTO X and More (Black).