How to Turn On Optimised Battery Charging on iPhone

Charging your iPhone to 100% and leaving it plugged in all night is convenient, but it is one of the fastest ways to wear the battery out. Apple built a feature called Optimised Battery Charging to solve exactly this problem. It learns your daily routine and delays the final part of charging until just before you need the phone. Here is how it works and how to make sure it is switched on.

Quick Answer

Go to Settings, tap Battery, then Battery Health & Charging, and turn on Optimised Charging (on newer iPhones, choose “Optimised” under Charging Optimisation). With it enabled, your iPhone charges to about 80% and waits there, finishing the last 20% shortly before your usual wake-up time, which reduces battery ageing.

How Optimised Charging Works

A lithium-ion battery wears out fastest when it sits at a full charge for hours, especially while warm. Optimised charging avoids that. Using on-device learning, your iPhone studies the times you normally plug in and unplug. When it predicts a long charge, such as overnight, it stops at around 80% and holds there. Then, roughly an hour before you usually wake up, it tops the battery up to 100% so the phone is ready when you are.

Because the learning happens on the phone itself, your routine data is not sent to Apple. The feature needs some location settings to work out where you spend significant time, such as your home, because it mainly activates in places where you charge for long periods.

Step-by-Step: Turn It On

1. Open Settings and tap Battery.
2. Tap Battery Health & Charging.
3. On most models, simply switch on Optimised Battery Charging.
4. On the iPhone 15 and newer, tap Charging Optimisation and choose Optimise from the list of options.
5. Make sure Settings > Privacy & Security > Location Services > System Services has Significant Locations enabled, as the feature relies on it.

Give the feature about two weeks of regular routine to learn your habits. If your schedule changes every day, such as shift work, the predictions will be less reliable, but the feature will not harm anything by trying.

The Charging Options on Newer iPhones Explained

On the iPhone 15 series and later, including the iPhone 17 and 18 families, you get three choices instead of a simple switch:

• Optimise: the smart option described above, best for most people.
• 80% Limit: the phone never charges past 80%. This gives the longest possible battery lifespan and suits people who are near a charger all day.
• None: the phone charges to 100% as fast as possible every time, with no protection.

If you plan to keep your phone for three or four years, the 80% limit is surprisingly practical. Most people never truly need the last 20% on a normal day, and the battery stays healthier for far longer. You can read your current health figure any time using our guide on checking iPhone battery health and maximum capacity.

How to Charge Past the Limit When You Need To

Sometimes you know you will have a long day away from a charger and you want a full battery. When your phone is holding at 80% with optimised charging, a notification appears on the lock screen telling you when charging will finish. Tap and hold that notification and choose “Charge Now” to push straight to 100%. On models with the 80% limit setting, temporarily change the setting to Optimise or None the night before a big day.

Why Is Optimised Charging Not Working?

If your phone still charges straight to 100%, work through these checks. First, the feature needs a consistent routine, so irregular hours can defeat it. Second, Significant Locations must be on, and the phone needs to learn your main charging place. Third, if you recently got the phone or reset it, the learning starts from zero. Finally, alarms help: setting a regular wake-up alarm gives the phone a clear target time to finish charging.

Apple explains the reasoning behind the feature on its page about how and why lithium-ion batteries age, which is worth a read if you want the science behind the 80% figure.

Mistakes to Avoid

The biggest mistake is turning optimised charging off because the phone was “only” at 85% one morning when you woke up early. An unusually early start catches the feature out now and then; it is not broken. Another mistake is combining a thick case, wireless charging and a hot room overnight, which adds heat stress that no software feature can undo.

What the Research on Charging Habits Shows

The reason Apple, and now almost every phone maker, builds features around the 80% mark is that lithium-ion battery wear is not linear. A battery kept between roughly 20% and 80% can last far more charge cycles than one regularly pushed to 100% and drained to zero, because the chemical stress is highest at the extremes of charge. Heat multiplies the effect: a full battery in a hot environment ages faster than any other combination, which is why overnight charging on a warm nightstand used to be the worst common habit before optimised charging existed.

You do not need to obsess over perfect numbers. Real life needs full charges before travel days, and the occasional 100% does no meaningful harm. The benefit of optimised charging is that it handles the everyday pattern automatically, the 300 ordinary nights a year when you did not need a full battery by 6 a.m. but the phone sat at 100% for six hours anyway. Removing that background wear is what adds months, and eventually years, to the useful life of the battery.

If you regularly wake to find the phone has charged fully despite the feature being on, check that your alarm and routine are consistent, and remember the phone favours being ready over being gentle: when in doubt, it charges. That is the right priority, and it means the feature protects you quietly in the background without ever leaving you short of charge.

Conclusion

Optimised Battery Charging is one of the simplest free wins for iPhone owners. Turn it on in Settings > Battery > Battery Health & Charging, keep Significant Locations enabled, and give it a couple of weeks to learn your routine. Your battery will spend far less time sitting at a stressful full charge, and it will hold its capacity noticeably longer.

Travelling and Irregular Schedules

Optimised charging is built around routine, so travel tests it. In a new time zone or a hotel, the phone may simply charge to full because it cannot predict your morning, and that is the correct behaviour: being ready matters more than being gentle on a travel day. Shift workers see the same effect across rotating patterns. The feature still helps on the ordinary weeks at home, which make up most of the year. If your schedule is permanently irregular, the fixed 80% limit on newer models is the more dependable protection, because it needs no predictions at all; it simply never lets the battery sit in the high-stress zone, whatever your hours.

Frequently Asked Questions

Does optimised charging slow down charging speed?

It does not slow the first part of charging at all. The phone charges quickly to about 80%, then pauses, and finishes near your wake-up time. The total speed to 80% is the same as normal charging.

Why does my iPhone sometimes charge to 100% anyway?

If your routine changes, you travel, or the phone cannot predict a long charging session, it charges fully as a safety measure. Occasional full charges are harmless and also help the battery gauge stay accurate.

Is the 80% limit better than optimised charging?

For maximum battery lifespan, yes, because the battery never reaches a full charge. For convenience, optimised charging is better since you still get 100% on the days you follow your normal routine. Choose based on how close you stay to a charger.

Does optimised charging work with MagSafe and wireless chargers?

Yes. It works with Lightning, USB-C, MagSafe and Qi wireless charging. The learning is about your routine and location, not the type of charger you use.

Do I need an internet connection for it to work?

No. The learning and predictions happen on the device itself. You only need the relevant location services switched on so the phone recognises your regular charging places.