You've probably seen those external battery packs made for smartphones. Also known as power banks, they come with an embedded rechargeable battery and a USB port providing back-up power for our mobile gadgets. And if you do a little research, you'll discover that they come in all shapes and sizes. Here's for example a post listing some of the largest smartphone battery packs money can buy.
Now, having a large power bank on hand is great, there's no denying that. Some larger models, however, can be too bulky to carry around all the time. That's why we dug out some of the smaller external power packs on the market. Keep in mind that not all of them can charge a high-end smartphone completely. After all, a small power bank can't hold a very large battery. However, they are all portable enough to be easily stored in a pocket, backpack, or purse. Check them out in the slideshow below.