The Motorola Droid Turbo promises a whopping 48 hours of battery life during mixed usage, but how long does it last under heavy use? As it turns out, its high-capacity 3,900 mAh battery delivers good endurance, but it's not best in class.

To gauge the staying power of the Droid Turbo, we ran our standard Android battery test, which involves surfing 50 of the most popular websites over 4G LTE on 150 nits of brightness. Verizon's new exclusive device lasted 9 hours and 30 minutes. That's more than an hour longer than the smartphone average and the Verizon Galaxy S5.

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However, other handsets last longer. The HTC One M8 on Verizon, for instance, ran for a solid 9:52 on our test. And although it was on AT&T's network, the iPhone 6 Plus lasted a half hour longer than the Turbo at 10 hours even. Although it has a smaller 3,100 mAh battery, the OnePlus One offered more than 13 hours of power.

To be fair, the Turbo is likely working harder than some competing handsets because it has more pixels to render on its 5.2-inch QHD (2560 x 1440) screen. The Galaxy Note 4, which has a larger 5.7-inch QHD display, lasted for 8:43 on AT&T. The Verizon version of the LG G3 sports a 5.5-inch QHD panel and lasted only 6 hours and 10 minutes on our test.

If you read the fine print on its website, Motorola doesn't claim that the Droid Turbo lasts 48 hours on a demanding test like the one we run. The company's estimate is "based on an average user profile that includes both usage and standby." Still, we were hoping that the Turbo would break the 10-hour mark.

The good news is that Motorola claims that you'll be to get 8 hours of juice after recharging for just 15 minutes. We'll put that claim to the test in our full review.

Mark Spoonauer is the editor in chief of Tom's Guide. Follow him at @mspoonauer. Follow Tom's Guide at @tomsguide, on Facebook and on Google+.