Replace your iPhone battery when it no longer holds a full day of normal use, when iOS reports battery health below 80 percent, or when the phone shuts down unexpectedly at high battery percentages.
iPhones use lithium-ion batteries that degrade over time. A new iPhone battery holds a full charge; after roughly 500 complete charge cycles (a full drain and recharge), the battery retains about 80 percent of its original capacity. After 1,000 cycles, it typically holds 60 to 70 percent. One charge cycle takes about one month of normal daily use, so most people notice a real difference after two to three years.
You do not have to wait until the battery fails completely. Replacing it when capacity drops below 80 percent costs less than repairing water damage or a cracked screen caused by a phone that shuts down unexpectedly in your pocket. Apple and most repair shops can replace the battery in one to three hours.
Key Takeaways
- Check your battery health in Settings > Battery > Battery Health & Charging to see the exact percentage your battery retains.
- Battery health below 80 percent means the battery is degraded enough that replacement will noticeably improve daily use.
- Unexpected shutdowns at 20 to 50 percent battery are a sign the battery cannot deliver the power your phone needs, even if the percentage display says otherwise.
- Apple offers battery replacement at its stores and authorized repair shops; independent repair shops often charge less but may not use Apple parts.
- If your iPhone is still under warranty or covered by AppleCare+, battery replacement may be covered at no cost.
How to Check Your Battery Health Right Now
Open Settings on your iPhone, then tap Battery, then Battery Health & Charging. You will see a percentage labeled "Maximum Capacity." This number tells you what fraction of the original charge your battery can now hold. A new iPhone shows 100 percent. If yours shows 80 percent or lower, the battery has degraded enough that most people notice shorter battery life during the day.
You will also see a line labeled "Battery Health." If it says "Normal," your battery is functioning as expected for its age. If it says "Degraded" or "Service Recommended," Apple is telling you the battery should be replaced soon. "Service Required" means the battery may fail without warning and should be replaced when ready.
Signs Your Battery Needs Replacement Before It Fails
The most common sign is that your phone no longer lasts a full day with normal use. If you used to unplug in the morning and still have 20 percent at bedtime, but now you are at 5 percent by mid-afternoon, the battery is degraded. This happens gradually, so you might not notice day to day—but comparing your phone's endurance to last year will show the difference.
A second sign is unexpected shutdowns. If your iPhone powers off when the battery percentage shows 30 percent, 40 percent, or even higher, the battery cannot deliver the current your phone needs at that moment. The percentage display is an estimate; the actual voltage has dropped too low. This is dangerous because your phone may shut down while you are using it, and you cannot predict when it will happen.
A third sign is that your phone gets warm during normal use—not during a video call or game, but during light tasks like texting or email. A degraded battery works harder to deliver power, which generates heat. If your phone feels warm in your hand during everyday tasks, the battery is likely near the end of its life.
When Battery Replacement Is Covered by Apple
If your iPhone is within one year of purchase and the battery health has dropped below 80 percent due to a manufacturing defect (not normal wear), Apple will replace it at no cost under the standard warranty. You will need your receipt or proof of purchase.
If you have AppleCare+, battery replacement is covered at no cost as long as the coverage is active, regardless of how degraded the battery is. AppleCare+ costs between $99 and $379 depending on your iPhone model and is usually purchased when you buy the phone, though you can sometimes add it later.
If your iPhone is out of warranty and you do not have AppleCare+, Apple charges a flat fee for battery replacement. This fee varies by model—typically $69 to $99—and is the same whether your battery is at 79 percent or 20 percent capacity. The replacement usually takes one to three hours at an Apple Store, or you can mail it in if no store is nearby.
Repair Options Beyond Apple
Independent repair shops and some electronics retailers offer iPhone battery replacement, often for $30 to $60 less than Apple charges. The trade-off is that they may not use genuine Apple batteries. A non-Apple battery will work, but it may not last as long or report its health accurately to iOS.
Before choosing an independent shop, ask whether they use Apple-certified parts or third-party batteries, and whether they can transfer your data if something goes wrong during the repair. Some shops offer a warranty on the replacement battery; others do not. Read recent reviews on Google Maps or Yelp to see whether customers report problems weeks or months after the repair.
If your phone is still under warranty, going to an unauthorized repair shop may void the warranty for other components. Check your warranty status at apple.com/support before deciding.
What Happens If You Wait Too Long
A battery that has degraded to 50 percent capacity or lower will shut down without warning, sometimes multiple times a day. Your phone may restart on its own, lose unsaved work, or disconnect from calls or messages. If this happens while you are driving, navigating, or in an emergency, it creates a real safety risk.
A severely degraded battery can also swell inside the phone, pushing the screen or back panel outward. This is rare but dangerous—a swollen battery can catch fire. If you notice your phone's back panel is no longer flat or the screen is lifting at the edges, stop using it and take it to a repair shop when ready.
Waiting for the battery to fail completely also means you may damage other components. A phone that shuts down unexpectedly can corrupt data or damage the logic board if it powers off during a write operation. Replacing the battery before it reaches this point is cheaper than repairing water damage or data loss.
How Often You Will Need to Replace the Battery
Most people replace their iPhone battery once every two to four years, depending on how much they use the phone and how they charge it. If you charge your phone to 100 percent every night and drain it to 0 percent every day, the battery will degrade faster than if you keep it between 20 and 80 percent most of the time.
iOS includes a feature called "Optimized Battery Charging" that slows degradation. It learns your charging habits and holds the battery at 80 percent until shortly before you usually wake up, then charges to 100 percent. You can turn this on in Settings > Battery > Battery Health & Charging. Using this feature can extend the time between replacements by several months.
Frequently Asked Questions
Can I replace my iPhone battery myself?
You can, but it is not recommended unless you have experience with phone repair. The battery is glued to the phone and requires special tools to remove safely. If you damage the screen, logic board, or battery connector during removal, the repair cost will be much higher than paying a shop. Apple and authorized repair shops are the safest option.
Does iOS tell me when my battery needs to be replaced?
Yes. If your battery health drops below 80 percent, iOS will show "Battery Health" status in Settings. If it drops further, you may see a notification saying "Battery Health Degraded" or "Service Recommended." However, you should check manually every few months rather than waiting for a notification, because the notification does not always appear when ready.
Will a new battery make my old iPhone feel like new?
A new battery will restore battery life to what it was when the phone was new, but it will not speed up the processor or improve performance in other ways. If your iPhone is slow because of age, a new battery alone will not fix that. However, if slowness is caused by iOS throttling the processor to protect a weak battery, a new battery may improve speed.
What should I do with my old battery after replacement?
Do not throw it in the trash. Lithium-ion batteries can catch fire in landfills. Apple and most repair shops will recycle the old battery at no cost. If you replace the battery at an independent shop, ask whether they recycle it or if you need to take it to a recycling center. Many electronics retailers like Best Buy also accept old batteries for recycling.
Can I use my iPhone while it is being repaired?
No. The repair takes one to three hours, and your phone will be powered off during the battery replacement. If you need your phone during that time, you can ask the shop to do the repair while you wait, or you can arrange a loaner phone if the shop offers one. Mail-in repairs take longer—usually five to seven business days plus shipping time.