With removable batteries starting to become extinct, portable battery packs like this one from Aukey have begun to become pretty popular. Aukey here has a 15,000mAh battery pack that is about 5x the size of your smartphone battery. Additionally it has Quick Charge 2.0 built in. Which will charge your phone about twice as fast as a normal charger. Of course, that's only on phones with a Snapdragon 800, 801, 805, 808 or 810 processor inside. It's great being able to charge your phone faster, even while being away from the outlet. There are two USB ports on this power bank from Aukey, with one being Quick Charge 2.0 and the other being a standard charger, which is going to be quite a bit slower. Aukey has also included a flashlight, which can be turned on by holding the power button. Definitely a nice addition to this power bank, especially if you're ever in the dark and need a flashlight to see. this way you aren't using the power from your phone.
This power bank from Aukey would normally go for around $35, but right now it's on sale for just $22. However you do need a promo code. Which you will find down below.
Aukey Quick Charge 2.0 15000mAh Portable External Battery Fast Charger - $22 w/ code VLS2CENC