The trouble with making phones thinner and lighter is that the internal components need to shrink each time, which isn't always an easy ask - and that might be why Samsung is said to be putting a 2,600 mAh battery inside the Galaxy S6.
That's a smaller battery than the 2,800 mAh sported by last year's Galaxy S5, and it's going to have users worrying about the impact on battery life even before it's on sale.
To make matters worse it sounds like the Galaxy S6 won't have a removable battery, as its predecessors had, so you won't be able to swap it out for a spare or an upgrade. And there are likely to be more pixels to power - 1440 x 2560 to be precise.
Size isn't everything
The speculation comes from a source in South Korea - a source of dubious legitimacy - but the manufacturer is certainly going to have to do something to accommodate the unibody design we're all expecting.
On a brighter note, there are indications that the Exynos 7420 SoC chip slated for the Galaxy S6 is so efficient that the phone will last longer on a single charge, despite the fact that the battery itself is smaller. It's a balancing act Samsung needs to get right.