iOS 7.1.1 is out, and iPhone users will probably notice a dramatic difference in the battery life of their phones. Adrian Kingsley-Hughes of ZDNet reports that he noted a major improvement, literally overnight.

Apple iOS 7.1.1

Before and after iOS 7.0

He said he has been watching and measuring battery life on both the iPhone and the iPad with every iOS update Apple Inc. (NASDAQ:AAPL) rolls out. He found that the last update—iOS 7.1—was horrible for his iPhone’s battery life and a number of other test devices. He said it went “from ‘great’ to ‘poor’ overnight.”

Before iOS 7.0, he noted that his iPhone’s battery, after being fully charged, fell to 74% after six hours of use. After he upgraded to iOS 7.0, he did see a minor reduction in battery life, although he said it “came back to normal quickly,” so he chalked that up to battery calibration. He noted that some updates to Apple Inc. (NASDAQ:AAPL)’s operating system appear to wipe out the battery calibration data, so it may take a few cycles to get things back to the way before.

iOS 7.1 reduced iPhone battery life

He noted major battery problems after upgrading his iPhone to iOS 7.1. He said after six hours of use, he began to see his battery fall to about 48%, which was a big difference. As a result, he had to recharge his iPhone one during the day jut to make it through a full day. In fact, he said it was possible to “actually watch the battery counter drop” and that he “saw it drop several percentage points in one go” more than once.

The tech guru said even when using the tweaks he uses to improve battery life on his iOS devices, he was only able to squeeze “a few extra percentage points” out of it. He saw that Facebook Inc (NASDAQ:FB) was one of the largest users of battery life, so after removing it, he was able to get 61% after six hours of use, but that was still a significant drop from where it had been.

With iOS 7.1.1

He said after updating to iOS 7.1.1, he noticed major improvements. One of those improvements is that the battery life falls to just about 76% after six hours of use, which is even slightly better than what he was getting before iOS 7.0.