How to know when it's time to replace your iPhone battery

🧰 Difficulty: ★★☆☆☆ (Easy to check, tricky to replace)

⏱ Time involved: 10–15 minutes

⚠️ Risk level: Low for testing, high if you open it up.

💡 Pro insight: We see plenty of DIY battery swaps gone wrong—swollen batteries and cracked screens are common.

⚙️ Play it safe—visit a nearby uBreakiFix® by Asurion store for an expert battery replacement.

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No matter what you do, your iPhone® battery has a limited shelf life. As it ages, the battery slows—so a full charge won't last as long. Most batteries are good for at least 2 to 3 years, often longer, but how do you know when to replace your iPhone battery?

At Asurion, we help millions of people maximize their tech. From extending the life of your phone to using cloud storage on your computer, our experts offer total tech care to millions. Here are our tips on how to know when to change your iPhone battery.

How your iPhone battery works

iPhones run on rechargeable lithium-ion batteries. They charge fast and pack more power into a lighter battery than ever before. Older iPhones are more prone to battery issues than newer models, which are built with advanced features that compensate for poor battery health. But all batteries degrade over time.

iPhone battery issues to look out for

If your phone is unexpectedly shutting down and you can't get through a day with a single charge, you likely have battery problems. Other signs include sluggish apps and lower-than-usual speaker volume.

If your iPhone's screen is lifting, separating from the frame, or the device appears swollen, stop using it and have it inspected immediately. A swollen battery is a safety concern.

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How to check your iPhone battery health

To check the health of your battery, make sure your phone is charged and then go to Settings > Battery and tap Battery Health & Charging. Here, you'll find information on maximum capacity, cycle count, and important battery messages, as well as when to change your iPhone battery.

Let's take a closer look at what you might find.

(Note: You need an iPhone 6 or later device running the iOS 11.3 or later operating system. If your iPhone can't upgrade, contact an expert for help.)

iPhone battery maximum capacity

This percentage measures your phone's current battery capacity relative to when it was brand new.

• 100% to 80%: Your battery is considered healthy.
• Below 80%: Apple considers batteries below 80% significantly degraded, but replacement should also be based on real-world symptoms like short battery life, unexpected shutdowns, or performance issues.

If you have an iPhone 15 or newer, you can set a charge limit between 80% and 100% to help reduce battery aging.

Battery Cycle Count

On iPhone 15 and newer models, you can now see your Cycle Count directly in the Battery Health menu.

• A "cycle" is counted every time you use a total of 100% of your battery's capacity.
• Newer iPhone batteries are designed to retain around 80% of their original capacity after approximately 1,000 complete charge cycles under normal conditions.

Peak Performance Capability

This section tells you if your battery is still powerful enough to handle demanding tasks.

• Performance is normal: You will see "Your battery is currently supporting normal peak performance."
• Performance management applied: If your iPhone has shut down unexpectedly, you will see a message stating that performance management has been applied to prevent future crashes. You can choose to Disable this, but you cannot turn it back on manually—it will only re-enable if the phone crashes again.

Battery health degraded

If your capacity drops below 80%, you will see a "Service" message:

• "Your battery's health is significantly degraded. An Apple Authorized Service Provider can replace the battery to restore full performance and capacity."

Battery health unknown or non-genuine

If your iPhone cannot verify the battery, you may see one of the following:

• Unknown Part: This appears if the battery was replaced with a non-genuine part or if the installation was incomplete.
• Important Battery Message: "Unable to verify this iPhone has a genuine Apple battery. Health information not available."

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How to replace your iPhone battery

Replacing your battery is easy, cost-effective, and a great way to improve your phone's lifespan. There are DIY battery replacement kits out there, but you need to know exactly what you're doing, so your best bet is to contact an iPhone repair expert for help. Battery replacement costs start at $70, depending on your iPhone model.

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How to extend the life of your iPhone battery

While there's no way to stop your iPhone battery from aging, you can slow that process by following some best practices, from updating your version of iOS to avoiding using your phone in extreme temperatures. To learn more, check out our guide to saving your iPhone battery.

And if you're ready to swap out your battery, schedule an iPhone battery replacement service at the nearest

uBreakiFix® by Asurion store and our certified experts can get your device back up and running as soon as the same day.

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FAQ

Is 79% battery health bad on an iPhone?

Not automatically. Plenty of iPhones keep chugging along below 80%. But if you're always hunting for a charger, it's worth considering a battery replacement.

Should I replace my iPhone battery at 80%?

Think of 80% as a checkpoint, not a deadline. If battery life is frustrating you, it's probably time. If not, you may be able to keep going.

How many years does an iPhone battery last?

Most iPhone batteries last about 2–4 years. Heavy use can shorten that timeline, while lighter use can stretch it out.

Will replacing my iPhone battery make it faster?

Sometimes. A fresh battery won't turn your iPhone into the latest model, but it can help restore performance if battery wear is holding it back.

Is it worth replacing an iPhone battery instead of buying a new phone?

Usually. If your battery is the main problem, replacing it is often much cheaper than upgrading to a new device.

What are the signs of a bad iPhone battery?

Fast battery drain, random shutdowns, slow charging, overheating, or a battery health warning. If your screen starts lifting away from the frame, that's your cue to stop using it and get it checked out.