Hands-on with iOS 11.3 battery health features on a performance throttled iPhone

Zac Hall | Feb 27 2018 - 9:10 am PT

My iPhone X lost a fight with concrete on Sunday morning when I folded up my jogging stroller and forgot the phone in its storage compartment. The smashed iPhone X is on its way to Apple’s repair facility (yes, the one that makes all those 911 calls) and I’m living on an iPhone 6 Plus for the week.

A few observations: the modern haptic engine is light years ahead of the 2014 vibration motor, cameras on newer iPhones have improved dramatically, and older iPhones feel slow in comparison with or without throttling. More on my experience with a throttled iPhone so far below.

In 2014, iPhone 6 and iPhone 6 Plus were absolute powerhouses. The first 4.7-inch and 5.5-inch iPhones finally gave Samsung a run for their money with smartphones larger than 3.5- and 4-inches which lead to a super cycle of upgrades that Apple still strives to repeat.

The general look of the iPhones that cost under $1000 has not changed since 2014 either, so I could understand someone holding on to an iPhone 6 or iPhone 6 Plus and waiting to upgrade when something similarly priced and but with an all new design hits the market. That’s the expectation this year for the 2018 fall lineup which is expected to include a 6.1-inch LCD iPhone that looks like the iPhone X but costs more like the iPhone 8.

So what’s life like for iPhone 6 and iPhone 6 Plus users running the latest (and most secure) software versions? It’s pretty slow with or without throttling, which means a new battery may not remedy speed complaints for everyone.

Being able to see battery health data and know whether or not your performance is being throttled is absolutely enlightening for this reason. Otherwise I would swear general use was already being throttled when it’s not.

Restoring an iPhone has a big hit on performance, but even after that process is complete three-year old iPhones on modern operating systems can be frustratingly slow in day-to-day use.

Don’t get me wrong, this iPhone 6 Plus is totally usable for almost everything I use my iPhone X for, but every interaction has an expected delay and sometimes requires force quitting apps to get the job done. Tasks like launching the Camera app to snap a photo, launching the Phone app to switch from recent calls to the keypad, and using Siri — before throttling.

iPhones with older batteries that are throttled will be reset when iOS 11.3 is released, then throttling will kick in after the first unexpected shutdown. The user can disable throttling again, but throttling will kick back in after the next unexpected shutdown and can’t be re-enabled manually.

So what does this look like in a real world scenario? My iPhone 6 Plus reports 84% maximum battery capacity which means it won’t last as long in between charges as it would if it had a new battery. Throttling was off by default and it only took a few hours for an unexpected shutdown to occur.

It happened around lunch time when the iPhone 6 Plus showed 59% battery remaining. I attempted to log my meal with my calorie counting app, and launching the app was excruciatingly slow. I looked away for a few minutes then checked back and the iPhone was powered off. Attempting to power it back up showed the battery charge indicator.

In this real world scenario, I actually missed an important work phone call in between the shutdown and powering back up by recharging. For this reason, I am now totally on the side of performance management to avoid unexpected shutdowns (although it would obviously be ideal to not have to worry about that either).

After charging for a few minutes, the iPhone 6 Plus booted back up showing around 20% battery and included an alert about the shutdown and throttling:

This iPhone has experienced an unexpected shutdown because the battery was unable to delivery the necessary peak power. Performance management has been applied to help prevent this from happening again.

I’m not sure if the alert was actionable (i.e. if it could take you to power management settings), but I followed up with checking the battery health section which updated to say throttling was happening.

I ran the iPhone in this state for a few hours before opting out of performance management for further testing. Next time the iPhone experiences an unexpected shutdown, throttling should kick back in and I won’t opt out.

Benchmark results don’t always capture the experience of normal usage, and the numbers I captured before and after throttling surprised me.

The process of restoring the iPhone seemingly took a bigger hit to performance than applying throttling. The 9:42 am results were noticeably slower before throttling than the 1:54 pm results after throttling was applied. I’m attributing this to the impact that restoring an iPhone from a backup has on performance, but I’ll continue testing until my iPhone X is returned later this week.

The key takeaway for me personally is that either we misremember how well these iPhones performed with their original software or modern software updates that aren’t optimized for older hardware have a serious impact on performance — or both.

Another factor to experiment with would be actually replacing the battery and comparing that performance on iOS 11.3 (which is also still in beta and not optimized for release yet) to the throttled performance. Performance management is primarily intended to prevent unexpected shutdowns during peak performance, but it’s not a total fix for a three-year old battery.

Stay tuned for further testing in future betas and scenarios, and read more about performance management and solutions below:

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