The best waterproof portable charger is the Unifun Waterproof External Battery. This charger has enough capacity to charge an iPhone 6 about 4 times. It has two USB ports to charge two devices simultaneously. One port has a higher amperage for charging tablets.
The Unifun Waterproof External Battery is great to have on hand for your outdoor excursions. It goes where standard portable chargers can’t: poolside, camping, skiing and just about anywhere there’s a chance of dust or precipitation. That’s why its trusted by first responders as well as vacationers.
The battery takes around 5-7 hours to charge after it expends all 10,400mAh. When it is charged up, the Unifun can fully charge about four empty smartphones. It is compatible with a wide range of gadgets, including the iPhone 6 Plus 5S, 5C 4 4S, iPad Air/iPad Mini, Samsung Galaxy S5 S4 S3, Google Nexus 7, cameras, and tablets. It does automatically power down when it is not in use, which helps keep it going for longer. Unifun claims that the lithium polymer core has a long lifespan and can give up to 1,000 lifetime charges, which is above industry standard.
We also like the battery’s durable casing. It is IP66 waterproof rated, which means it is totally dust-proof and protected against string water jets and waves. One caveat: don’t expect a quick charge with the Unifun. It charges about 1% every five minutes, so it will take a device a while to get back to life if you let it completely expire.
The Limefuel Rugged L104XR is another durable waterproof portable charger option. As its name suggests, the Limefuel Rugged can take a beating and has an IP66 rating. It has 2 universally compatible outlets equipped with 5V/2A input.
The Limefuel charges devices faster than the Unifun and both are 10400mAh, but the Limefuel has a shorter lifespan than its competition. It is good for 500 cycles, about half as many as the Unifun.