Even though the phone has yet to release in the US and the UK just yet, the Samsung Galaxy Note 4 has already started receiving a new update which will supposedly increase its battery life significantly. The update is firmware version XXU1ANJ4 and clocks in at 36MB. The update has already been fully distributed OTA, so that likely means when you get your Note 4 it will start downloading the update as soon as you power it on.
Some folks were skeptical that the batter life on the Note 4 would be able to match the legendary efficiency of the previous generation Note 3 because of the QHD display drinking more juice; however, with the massive 3220 mAh battery in the Note 4, and this new update, the new Note 4 might be just as good as the Note 3. The new update supposedly includes some bug fixes as well to improve the deices stability.
Source: SamMobile