This is Apple's trick for longer iPhone battery life in iOS 9

Benchmarks suggest an iPhone's battery can last for several hours longer.

Low power mode in iOS 9 running on the iPhone 6 (Image: ZDNet/CBS Interactive)

Let's talk about battery life. It sucks, and everyone knows it.

Most of us struggle to get more than half-a-day of battery life out of our phones on moderate use. As our smartphones get hungrier for power, battery life continues to plunge. Phone makers are sacrificing basic functionality for style, thinness, and weight. Apple is no exception. It's one of the worst offenders.

Apple can't solve that problem until it lifts the veil on the new iPhone, expected later this year. But it has a fix in place in the meanwhile: a "low power mode."

Here's why many "free" apps drain your smartphone battery

And here's how you can get that power back...

Read More

Buried within the settings in iOS 9, Apple has a new section dedicated to helping users manage their power settings better.

The power-saving mode gives you the option of kicking in when you reach the 20 percent level. By turning off battery-hungry functions, like push email fetching and automatic downloads, the mode conserves your battery for when you need it most. It also reduces your processor clock speed, further lowering how much power is consumed by your phone.

The feature can't come soon enough for some users, who have complained about poor battery life since the iPhone's inception. Google included a similar feature into its Android software years ago.

Apple's Low power mode is said to conserve up to three hours from full charge, reports say, while other battery-saving improvements can squeeze an extra hour out of the battery compared to iOS 8. (Apple said at its annual developer conference to expect about an hour extra battery life from the software update.)

According to MacRumors, which benchmarked the new feature, device performance is lowered by about 40 percent, putting the latest iPhone 6 in line with the performance of an older iPhone 5 or iPhone 5s.

Anecdotal evidence suggests that the feature, introduced in the first beta of the software, is far more effective in the second beta, released to developers last week.

The section also includes a list of which apps are consuming the most power to help users manage their app consumption better.

Apple is scheduled to release iOS 9 as a public preview in July.