RAVPower’s newest battery pack is very similar to the reader-favorite Anker PowerCore Fusion, but with double the battery capacity (10,000mAh vs. 5,000mAh). For a battery pack that plugs directly into an AC outlet, that does mean that it might be more susceptible to falling out of worn out, loose-fitting outlets, but at $19 (with promo code KINJA066), it wouldn’t hurt to try it out.
The real appeal of these things is that you only have to take one charger with you when you travel. This can act as your wall charger at night, and your battery pack during the day, all without the need to futz with microUSB cables to recharge it.