Replace your iPhone battery when it no longer holds a charge through a normal day, or when the phone shuts down unexpectedly even with battery percentage remaining
Your iPhone battery degrades over time. Apple designs them to retain 80 percent of their original capacity after 500 full charge cycles — roughly two years of normal use. Once you hit that point, the battery still works, but it loses charge faster and may not power your phone through a full day.
You do not have to wait until the battery fails completely. The right time to replace it is when the behavior changes enough to disrupt your day: when you need to charge twice instead of once, when the phone shuts down at 20 percent battery, or when apps close unexpectedly because the system thinks power is too low.
Key Takeaways
- Replace your battery when it no longer lasts a full day of normal use, or when your iPhone shuts down unexpectedly with battery percentage still showing.
- Apple's battery health tool in Settings shows the maximum capacity your battery can now hold — anything below 80 percent means the battery has degraded significantly.
- Unexpected shutdowns happen when the battery cannot deliver the power the phone needs, even if the percentage display shows charge remaining.
- Battery replacement costs between $69 and $99 at Apple, depending on your iPhone model, and takes one to two hours at most Apple Stores.
- Third-party repair shops often charge less but may use non-Apple batteries, which can affect performance and may not be covered by your warranty.
How to check your battery health right now
Open Settings, tap Battery, then Battery Health & Charging. You will see a number labeled "Maximum Capacity" — this is the percentage of the original charge your battery can now hold. If it shows 80 percent or higher, your battery is still within normal wear. If it shows below 80 percent, the battery has degraded enough that you will likely notice shorter battery life.
The same screen shows "Condition" — if it says "Normal", your battery is functioning as expected for its age. If it says "Service Recommended" or "Service Battery", Apple is telling you the battery has degraded enough that replacement would improve performance. "Poor Condition" means the battery is failing and should be replaced soon.
This tool does not predict when your battery will fail. It shows you its current state. A battery at 75 percent capacity may still last all day if you use your phone lightly, or it may not last through afternoon if you use it heavily.
Why iPhones shut down before the battery is empty
A degraded battery cannot deliver power as quickly as the phone demands it. When you open a demanding app or use the camera flash, the phone needs a sudden burst of power. An old battery cannot provide that burst, even if it has charge remaining. The system shuts down to protect the battery from damage.
This is why you might see 20 percent battery remaining, then the phone powers off, and when you turn it back on it shows 5 percent. The percentage display is based on voltage, but the battery cannot actually deliver that power. Replacing the battery fixes this because a new battery can deliver the power the phone asks for.
The cost and time for battery replacement at Apple
Apple replaces iPhone batteries for $69 to $99 depending on your model — older phones cost less, newer ones cost more. The replacement takes one to two hours at most Apple Stores if you walk in without an appointment, though you can schedule ahead to skip the wait. Apple also offers mail-in service if no store is near you, which takes about a week total.
If your iPhone is still under warranty or covered by AppleCare+, battery replacement is free if the battery is defective. If the battery has straightforward degraded from normal use, you pay the standard fee. AppleCare+ costs $99 to $199 upfront depending on your model, but covers accidental damage and battery replacement for two years.
Third-party repair shops and what to expect
Independent repair shops and big-box retailers like Best Buy often replace iPhone batteries for $40 to $60, less than Apple charges. The trade-off is that they may use non-Apple batteries, which can affect performance or longevity. Some shops use quality third-party batteries that work well; others use cheaper ones that degrade faster.
If you use a non-Apple battery, you lose any remaining warranty coverage on the phone itself — Apple will not service a phone that has been opened by someone else. You also cannot return to Apple later if the third-party battery causes problems. Ask the shop what battery they use and whether they may provide it, and understand that you are taking on the risk if something goes wrong.
Signs you should replace the battery soon, not later
Replace the battery within the next month if your phone shuts down unexpectedly, even once. This is a sign the battery cannot deliver the power your phone needs, and it will happen more often as the battery ages. Waiting risks losing work or missing important calls.
Also replace soon if the maximum capacity has dropped below 70 percent and you use your phone heavily — for work, navigation, or streaming. A battery at 70 percent capacity will not last a full day under heavy use, and you will spend more time charging than using the phone.
If the maximum capacity is between 80 and 90 percent and you use your phone lightly, you can wait. The battery will continue to degrade, but you may get another six months or a year before it becomes a problem. Check the battery health every few months to watch the trend.
What happens if you ignore a failing battery
The phone will shut down more often and at higher battery percentages. You will need to carry a charger everywhere or use a portable battery pack. The shutdowns can corrupt files if they happen while you are saving something, though this is rare.
A very old battery can swell inside the phone, which pushes the screen or back panel outward. This is dangerous and requires when ready replacement. If you notice the phone feels thicker, the screen is separating from the body, or the back is bulging, stop using it and take it to Apple or a repair shop right away.
Replacing the battery does not restore the phone to brand new. It fixes the battery problem only. The processor, screen, and other parts continue to age. But a new battery often makes an older phone feel responsive again because you are not constantly managing low power mode.
Frequently Asked Questions
Can I replace my iPhone battery myself?
You can, but it is difficult and risky. iPhones are glued together, and opening one requires heat, special tools, and careful technique. If you crack the screen or damage the logic board, the repair cost becomes $300 or more. Unless you have done this before, having a professional do it is safer and not much more expensive.
Does replacing the battery affect my data or apps?
No. The battery is a separate component. Your data, photos, and apps stay on the phone. The technician removes the old battery and installs a new one without touching the storage or processor.
Should I replace the battery before I sell my iPhone?
Only if the battery health is below 80 percent and you want to get a better price. A phone with a degraded battery sells for less because the buyer will need to replace it soon. A new battery costs $69 to $99, so if replacing it increases the sale price by more than that, it makes sense to do it first.
Will a new battery make my old iPhone faster?
Not directly. The processor and storage do not change. But a new battery removes power limits that slow the phone down. When a battery is failing, iOS reduces performance to save power. A new battery means the phone can run at full speed again, which makes it feel faster.
How long does a replacement battery last?
A new Apple battery lasts roughly two years or 500 full charge cycles before it drops below 80 percent capacity, the same as the original. How fast you reach that depends on how often you charge and how you use the phone. Heavy daily use reaches 500 cycles in about 18 months; light use takes closer to three years.