The Lenovo Yoga 3 Pro comes with a 44.8 Wh internal battery, which is 17% smaller than the 54 Wh battery found in the Yoga 2 Pro. With the smaller battery in the Yoga 3 Pro, Lenovo themselves rate the battery life as being 20% less than the Yoga 2 Pro, claiming its good for 7.2 hours of life versus nine hours. Going just on Lenovo's data, this would suggest that the lower power rating of Intel's Core M chip doesn't improve battery life at all.
While I really liked many aspects of the Yoga 3 Pro, the area I was most disappointed with is the battery life, especially considering Intel was positioning their Core M chips as being extremely power efficient. I'm sure some of the blame can be leveraged towards Lenovo for reducing the size of the battery compared to the Yoga 2 Pro as well.
When I was writing this review entirely on the Yoga 3 Pro, I typically got around 5-6 hours of usage before I had to grab the charger. This was with display brightness at around 65%, with Wi-Fi connected as I was constantly browsing the web, and with Microsoft Word open. This is a typical use case for a device like the Yoga 3 Pro, and it's not exactly encouraging figures.
Battery life figures around the six hour mark can be attributed to the high resolution display which is reasonably power consuming at high brightness levels. Running the display at near 100% brightness would kill the battery in under four hours, so managing brightness is key to extending the life of the Yoga 3 Pro.
But as far as I'm concerned, six hours of battery life isn't good enough for a laptop of this class and this price. Getting eight or nine hours of life out of an Ultrabook isn't out of the question in 2014, with the MacBook Air rated at a whopping 12 hours, something the Yoga 3 Pro would seriously struggle to achieve even at the lowest power use.
If I were able to go a full work day (eight hours) without having to reach for a charger, I would be very happy with the Lenovo Yoga 3 Pro and Intel's latest Broadwell chip. But the choice to focus on slimness - which I also appreciate and love about this device - over battery life hasn't left the machine as balanced as I would like.
For those that are curious, I ran some battery benchmarks on the device, and recorded 5.01 hours of Wi-Fi browsing looping websites every 20 seconds in Chrome at 50% brightness. I also achieved 6.05 hours of 1080p video playback in the Windows Videos app at 75% brightness.