Apple has been putting a lot of effort into helping iPhone users prevent premature battery wear — an issue that’s plagued the iPhone for years.
One of the main ways that Apple has addressed this is with overcharging prevention. Lithium-ion batteries can suffer from overcharging, which can lead to the production of metallic lithium inside the cell, posing a fire hazard. By limiting the charge to 80%, the risk of battery damage through overcharging is significantly reduced.
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With iOS 13, the company introduced Optimized Battery Charging, a technology that extended the lifespan of the iPhone’s battery by reducing the time it spent fully charged. The tech uses on-device machine learning to learn the user’s daily charging routine, holding the charge at 80% and only completing the charge to 100% shortly before the user typically unplugs their phone.
With iOS 17, an 80% charge limit option was introduced; charging would be halted at 80% and only resume when the charge level hit 75%. Every so often, the battery is charged to 100% to ensure that information about the battery’s health and capacity is accurate.
Now — with iOS 18 — the operating system will take a more hands-on approach to improving battery life by recommending a specific charging limit to users through a notification. The latest iOS introduces a new set of charging options — 85%, 90%, and 95% — to choose from. The charge limit recommendation can also be found in the Settings app under Battery > Charging.
In the example below, the iOS 18 beta is suggesting to me — via highlighted green text — that I could get away with setting the limit at 85%.
iOS 18 beta is suggesting a charge limit of 85% for my iPhone 15 Pro Max.
Screenshot by Adrian Kingsley-Hughes/ZDNET
So, what’s going on here? Wouldn’t limiting charging to 80% be the best option for long-term battery health?
Probably, but not by a huge amount, and this is a compromise that will make people happier. While I’ve been more than happy with limiting my charge to 80%, there are a lot of people see a 20% cut in battery capacity as unacceptable. Additionally, newer batteries can handle being pushed more than batteries that have been through many months or even years of charge/discharge cycles.
Setting the charge limit to 100% triggers this message.
Screenshot by Adrian Kingsley-Hughes/ZDNET
The older the battery, the more sensitive it will be to overcharging, and the more wear it will suffer from being pushed too hard.
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As of the latest iOS 18 beta, this charge limit feature is only found on the iPhone 15 lineup; the option is not showing up for iPhone 14 handsets or older. I hope that Apple will roll this out to older handsets, as it will help keep older hardware in use for longer.
