Tech blog 9to5mac also claims that in constant use, the battery will die after just four hours.

However, the tech giant is believed to be still working on the software in a bid to improve battery life before its expected ship date in March.

'For the first time, people with knowledge of the Apple Watch’s development have provided us with the specific performance targets Apple wants to achieve for the Apple Watch battery, but the actual numbers may fall short of those targets,' 9to5mac's Mark Gurman said.

'According to our sources, Apple opted to use a relatively powerful processor and high-quality screen for the Apple Watch, both of which contribute to significant power drain.'

It says that Apple wanted the Watch to provide roughly 2.5 to 4 hours of active application use versus 19 hours of combined active/passive use, 3 days of pure standby time, or 4 days if left in a sleeping mode,' it says.

However, the site's sources say that Apple will only likely achieve approximately 2-3 days in either the standby or low-power modes. 

Running a stripped-down version of iOS codenamed SkiHill, the Apple S1 chip inside the Apple Watch is claimed to be similar in performance to the version of Apple’s A5 processor found inside the current-generation iPod touch.

'We’re told that Apple has been shooting for roughly 19 hours of mixed usage each day, but that the company may not hit that number in the first generation version.'  

Nearly 3,000 test units are said to be currently roaming around as Apple tries to get the battery life of the product right.

It comes just weeks after leaked screenshots revealed the app owners will use on their iPhone.

Called the companion app, the shots reveal several new capabilities of the Apple Watch - including the ability to customise its display with a monogram. 

It also shows how users will rearrange the watch's display, moving the apps they want.  

'Within Apple, the application is currently called the Apple Watch "Companion” app for iPhone,' said Mark Gurman of 9to5mac, who revealed the screenshots.

'This application manages settings for Apple Watch applications, as well as settings for iPhone/Watch interactivity.'

Apple is putting the finishing touches to its Watch ahead of an expected launch in March - and yesterday released a test version of the software that will link it to an iPhone.

The latest release of iOS 8.2, expected to be launched within weeks, includes references to the much anticipated watch.

Apple Watch will link via Bluetooth and a special app on user's iPhone. 

'Inside of the Bluetooth Settings menu is a new panel specifically for pairing an iPhone with the Apple Watch,' said Mark Gurman of 9to5mac.

'Additionally, the instructions inside of the Bluetooth menu specifically indicate that Apple will release a dedicated 'Apple Watch app' for setting up and controlling the wearable device.

(dailymail.co.uk)