A firmware update for Microsoft's Surface Pro 2 appears to have drastically improved battery life, addressing one of the beefy tablet's biggest weak points.

Microsoft issued the firmware update shortly after the Surface Pro 2 launched. According to AnandTech, web browsing on Wi-Fi jumped to 8.33 hours, compared to 6.68 hours before the firmware update. Video playback also got a boost, from 6.65 hours to 7.73 hours.

Another test by The Verge yielded 8 hours and 51 minutes of battery life when cycling through web pages and still images. That's a 20 percent improvement over the 7 hours and 33 minutes achieved in the site's previous testing.

AnandTech says the update allows Surface Pro 2's Marvell Wi-Fi solution to reach lower power states than before. It's unclear why this functionality wasn't included at launch. In any case, the firmware update appears to validate Microsoft's claims of a 75 percent battery improvement over the original Surface Pro. The first-generation Pro lasted for about four or five hours on a charge, so a 75 percent improvement would put Surface Pro 2 battery life in the seven- to eight-hour range.

We're in the process of checking out the improved battery life using a real-life scenario, by keeping multiple browser tabs open, word processing, and using Twitter in Windows 8.1's Snap view. This type of use previously yielded a little under six hours on a charge at 50 percent brightness. While that's certainly enough for an evening on the couch or an afternoon working at a coffee shop, it's not quite the all-day battery life we were hoping for from the upgrade to Intel's "Haswell" processor.

Surface Pro 2 users don't need to do anything to get the update, as it should have installed automatically by now. You can check which updates have been installed by opening the Settings charm and going to PC settings > Update and Recovery > Windows Update and clicking "View your update history."