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(Pocket-lint) - Samsung's upcoming Galaxy Z Flip 4 might well change up the design of its clamshell phone, but a new leak suggests that it'll make a telling change under the hood as well.

Sammobile has got its hands on images of a new dual-battery system that will reportedly power the Z Flip 4, with a 2,555mAh unit paired with a smaller 1,040mAh one. This makes 3,700mAh in total capacity, which is a noticeable upgrade over the Z Flip 3.

That phone had a 3,330mAh battery, so you're talking about a decent uplift which could well result in better battery life for the actual user.

Of course, that all depends on whether Samsung is trying to eke more power-hungry features from the newer phone, too.

If it has an upgraded display, for example, the added battery capacity might be countered by the increased demand placed on it by the hardware.

The phone will apparently also now be able to charge at 25W speeds, though, so faster charging should be present regardless.

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We don't have any official word from Samsung about the Z Flip 4, but it's getting more and more heat in terms of rumours and leaks, so we might not be too far off hearing something more substantive.

Writing by Max Freeman-Mills.