The Apple Watch battery should keep running on average for around 19 hours, confirming Apple's initial statement that you'll need to charge it every night.
Apple news site 9to5Mac has managed to get hold of the battery benchmarks that Apple has set out and they show that the smart wearable will indeed be suffering from the same battery problems that have been facing Google's Android Wear smartwatches like the Asus ZenWatch and the Moto 360.
The leaked benchmarks state that the Apple Watch should be able to achieve 2.5-4 hours of active application use, and 19 hours of mixed use.
While this may not sound like much, it's important to point out that the Apple Watch looks set to be significantly more powerful than other smartwatches on the market.
For starters there's the Retina Display, that alone puts the consumption demands above those of most current smartwatches which are using much smaller resolution displays.
According to the same leaked information, the Apple Watch is running a cut down version of iOS while the S1 chip is incredibly powerful, offering the same performance as the A5 chip found in the current iPod Touch.