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How to Use iPhone Optimized Battery Charging

Diagram Depicting Lithium-Ion Battery Charging
image credit: ACS Publications

published by Chand Bellur
November 20, 2022 at 2:57 p.m.
  • Apple added Optimized Battery Charging in iOS 13 to help maintain your iPhone battery’s lifespan.
  • By default, iOS activates Optimized Battery Charging on all compatible devices.
  • The feature analyzes iPhone usage, postponing complete charging until it predicts you will use your device.
  • Users can deactivate the feature temporarily or shut it off entirely.

What is Optimized Battery Charging?

Apple added Optimized Battery Charging to iOS 13 to prolong your iPhone battery’s lifespan. By analyzing usage patterns, iOS can estimate when you will use your iPhone after plugging it into a charger.

For example, suppose you regularly plug in your iPhone overnight and wake up at 7 a.m. In that case, Optimized Battery Charging will charge your iPhone to 80%, pause, and then resume charging immediately before 7 a.m.

Why Does Optimized Battery Charging Pause at 80%

A lithium-ion battery is under stress any time it’s fully charged. According to Battery University:

Li-ion does not need to be fully charged as is the case with lead acid, nor is it desirable to do so. In fact, it is better not to fully charge because a high voltage stresses the battery. Choosing a lower voltage threshold or eliminating the saturation charge altogether, prolongs battery life but this reduces the runtime. Chargers for consumer products go for maximum capacity and cannot be adjusted; extended service life is perceived less important.

A battery is damaged when charged fully due to an oxidation film that accumulates on the cathode over time. According to Professor Jeff Dahn:

The cathode (positive electrode) develops a similar restrictive layer known as electrolyte oxidation. Dr. Dahn stresses that a voltage above 4.10V/cell at elevated temperature causes this, a demise that can be more harmful than cycling a battery. The longer the battery stays in a high voltage, the faster the degradation occurs.

This is why NASA only partially charges lithium-ion batteries in satellites. It’s not easy to get up there and replace them. By under-charging them, the batteries last much longer.

Apple’s Optimized Battery Charging works on the same principle. By postponing the saturation charge (over 80%), it prevents cathode oxidation. Also, it gives your iPhone time to cool down before running the saturation charge. Both voltage saturation and heat cause the cathode to accumulate an oxidized film.

How to Turn Off Optimized Battery Charging

Since Optimized Battery Charging is on by default, you don’t have to do anything to activate it. There are even a few good reasons to shut off the feature.

If you buy a new iPhone every 1-2 years, don’t worry about preserving battery life. Unless you’re a total iPhone junky, battery health will unlikely dip below 80% while you possess it. I trade in my iPhone every year so I don’t need to fuss over battery management. If it fails, it’s under warranty because I buy a new iPhone every year.

Also, if you’re very busy and rely on your iPhone for work, you want it fully charged. Sometimes I plug in my iPhone to charge during the afternoon and forget that Optimized Battery Charging is turned on. After a few hours, I see my iPhone is still not fully charged. That’s because of Optimized Charging. If you’re not aware and careful, the feature can leave a busy iPhone user with a partially charged phone.

Turning off Optimized Battery Charging is easy. If you’re very busy and need to use your iPhone a lot, turn it off.

iOS 16.1.1 Battery Health & Charging Screen

First, open the Settings app and tap on Battery. From the Battery screen, tap on Battery Health & Charging. You can now switch off Optimized Battery Charging. iOS will ask if you want to turn it off tomorrow or permanently.

iOS 16.1.1 Shows Option to Turn Off Optimized Battery Charging Permanently or Until Tomorrow

I recommend disabling the feature if you’re very busy because one of these days, you’ll end up with an under-charged device. The difference between an 80% and 100% charge is a few hours of iPhone usage. If you’re a busy professional, you’ll want a full charge and probably replace your iPhone often.

If you’re more frugal and replace an iPhone every few years, you want the battery to last. In this case, just shut off Optimized Charging whenever you need a full charge.

Apple makes this easy. If you’re charging your phone and Optimized Charging is activated (it may not be, even if you turned it on, because it depends on your usage patterns), you can override it simply by tapping on the notification. If you don’t see a notification, your iPhone isn’t executing Optimized Charging procedures, and your phone will charge to 100%.

Optimized Battery Charging Notification

iOS is much more intelligent today than when the feature debuted a few years ago. I use Optimized Charging, and when I plug in my phone during the day, iOS now realizes it should be fully charged. If I connect it to a charger overnight, then it postpones a full charge until just before I wake.

I actually switched off Optimized Battery Charging after writing this article. It’s not for me. I’m busy and need a fully charged iPhone. Also, I replace my iPhone every year. Fiddling over battery optimizations isn’t worth my time, but Appledystopia is a consumer-oriented website, so we will continue researching and writing about battery-preserving tips and techniques.

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