There's been a lot of talk surrounding the battery life of the Apple Watch following a scoop by 9to5Mac:
Apple initially wanted the Apple Watch battery to provide roughly one full day of usage, mixing a comparatively small amount of active use with a larger amount of passive use. As of 2014, 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. Sources, however, say that Apple will only likely achieve approximately 2-3 days in either the standby or low-power modes…
Apple has also been stress-testing the Apple Watch’s battery life with pre-bundled and third-party applications. Our sources say that Apple is targeting 2.5 hours of “heavy” application use, such as processor-intensive gameplay, or 3.5 hours of standard app use. Interestingly, Apple expects to see better battery life when using the Watch’s fitness tracking software, which is targeted for nearly 4 hours of straight exercise tracking on a single charge.
Initially I thought those numbers were brutal, but after some consideration I think 3.5 hours of standard use will suffice for most users.
Apple has consistently said the Apple Watch would require daily charging.
As an example, my 'day' begins at 6 AM and ends at midnight when I go to sleep, which means the Apple Watch would need to last 18 hours to make it through a full day. If we do a little bit of math given the estimated 3.5 hours of battery life, it means the Apple Watch could be 'active' - as in, the display is on and being used - for 20% of my day.
20% seems like a pretty high percentage, especially considering my iPhone is still my main source of communication. Of course, there will be people who try to game on the Apple Watch and who will be disappointed when it shuts off after a couple hours. Those will be the same people who will complain through every medium they can that the Apple Watch is a failure. For the average person however, I suspect 3.5 hours will be sufficient for all-day use.
Luckily, I don't think we will have to wait much longer for some answers from Apple.