Update: This sale has ended.

There's nothing worse than a dead phone. You can't Instagram your lunch, Waze your commute, or jam Spotify at the gym if your battery is empty. This is why you need a backup plan, like the Anker Astro E1 6700mAh High-Speed Portable Charger. It's on sale for $13.99 at Amazon right now. It typically sells for around $17, and has been priced as high as $22. Go with the black color since every other one will run you $20.

This power bank received 4.5 out of 5 stars based on 228 customer reviews. It's tiny -- the size of a candy bar, in fact -- and will charge your phone at least once depending on the device you have. Anker's exclusive PowerIQ technology will detect your device and charge your battery as quickly as possible.

You'll get the battery pack, a micro USB cable, travel pouch, welcome guide, and an 18-month warranty. It's a good idea to keep a spare phone charging cable in the travel pouch as well. You can pick up an AmazonBasics Lightning Cable for $6.49! Micro USB users, you can use the included cable, but a 6-foot one will only cost you $5.99. If you use USB-C, here's one for $6.99.

See at Amazon