Battery cases — "smart" or not — are for suckers and only highlight a modern smartphone's inability to last through an entire day without needing to be recharged.

Until we get a real battery breakthrough, cramming a bigger battery into a phone is the next best thing. That's exactly what the Oukitel K10000 phone packs. Whereas most smartphone batteries store between 1,500-3,000 milliamp-hours (mAh), the K10000 has a 10,000 mAh battery — good for 10 to 15 days according to a report from The Techolic.

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The K10000's big battery is also good for charging other devices. That's right, it works like a battery pack and can recharge an iPhone 6S Plus up to three times.

Other than the unusually large battery, the K10000 is a pretty average smartphone running Android 5.1 Lollipop. It has a 5.5-inch screen with 720p resolution (1,280 x 720), a 1GHz quad-core processor, 2GB of RAM and 16GB of internal storage (expandable via microSD card). It also supports dual SIM cards.

On the back is an 8-megapixel camera with LED flash, and the front camera is 2 megapixels. Nothing special.

Impressive as the K10000's battery life sounds, we have to sour things a bit. At best, a phone with a 3,000 mAh battery is good for around 1.5 days. Extrapolating on that data that we've seen time and again from our Android phone reviews over the years, the K10000 will probably only last up to about five days of "normal" smartphone use consisting of web browsing, texting, video playback and light gaming, which is still significantly longer than most phones.

It's more likely the 10-15 day battery life is referring to talk time, and who really talks anymore on their phones? Of course, it's possible the phone can last up to 15 days if you simply don't use it very often.

The K10000 is available for from Gearbeast for $239.99 and ships on Jan. 2.