If you own a smartphone then that sinking feeling you get as you watch your battery life tick away faster than your day will be all too familiar. The new Low Power Mode feature built into iOS 9 can help to alleviate that anxiety, but don't expect miracles.
To the end user Low Power Mode is something that they'll be prompted to turn on when battery life hits the 20 percent and 10 percent mark (it can also be found under Settings > Battery). According to Apple, enabling it "temporarily reduces power consumption." When enabled "mail fetch, background app refresh, automatic downloads and some visual effects are reduced or turned off." I've also noticed that it aggressively auto-locks the device every 30 seconds.
What the user sees is the screen being dimmed, a drop in performance, and the battery icon color changed to a fetching yellow. Oh, and users also see battery life tick away at a slower rate.
How much of a performance hit can you expect when you enable Low Power Mode? According to Geekbench 3 tests I've done, about 40 percent. This means that the iPhone 6's A8 processor runs at a speed that's something between that of the iPhone 5's A6 chip and A7 chip that was found in the iPhone 5s.
In real terms this performance drop is not as noticeable as you might think. Sure, the more performance intensive the task you're doing, the bigger the hit will be, but for general stuff such as messaging, browsing the web, calling people and such, the effect is minimal.
And now to tackle the question that you're all pondering: how much extra battery life will I get from Low Power Mode?
You're not going to like my answer, which is "it depends."
According to Apple, iOS 9 gives you an hour extra run time between recharges, and from the testing I've carried out, if you activate Low Power Mode when the battery hits the 20 percent mark then this ballpark figure holds true. But there are a lot of factors that can negatively affect battery life.
Here are just a few:
Then there's how you're using your iOS device. An iPhone that's in someone pocket waiting for a phone call or text message is going to see far greater battery gains than one that's being used to play Angry Birds or watch cat videos on YouTube over LTE.
Based on all these variables, your real world gains could be a few minutes or they could be a few hours.
So what's the best way to get the most from Low Power Mode? Simple. The sooner you turn it on, the more you'll get from the battery, so if you know it's going to be a long day, switch it on when your battery is at 80 percent rather than wait for the 20 or 10 percent warning.