Replace your iPhone battery when it no longer holds a charge through a normal day, when the phone shuts down unexpectedly at 20 percent battery, or when it has completed more than 500 full charge cycles.
Most iPhones start showing battery wear after two to three years of daily use. Apple designs iPhone batteries to retain 80 percent of their original capacity after 500 complete charge cycles — a cycle means draining the battery fully and charging it back to 100 percent. Once you hit that mark, the battery degrades faster. You do not have to wait until the battery is completely dead; replacing it before it becomes unreliable prevents the phone from shutting down at inconvenient moments.
The most practical signal is when your phone no longer lasts a full day with normal use. If you are charging twice a day or carrying a power bank, the battery has likely degraded enough to warrant replacement. A second clear sign is unexpected shutdowns — when your iPhone powers off even though the battery percentage shows 20 or 30 percent remaining. This happens because the battery can no longer deliver the power the phone demands, even though it still holds some charge.
Key Takeaways
- Replace your battery when it no longer lasts a full day of normal use or when your phone shuts down unexpectedly at 20 to 30 percent charge.
- Apple batteries are designed to retain 80 percent capacity after 500 charge cycles, which typically takes two to three years of daily use.
- You can check your battery health in Settings > Battery > Battery Health & Charging to see the maximum capacity percentage.
- Replacement costs range from $69 to $99 at Apple depending on your iPhone model, and takes one to two hours at an Apple Store or authorized repair shop.
- Third-party repairs are cheaper but may void your warranty and could use lower-quality batteries that degrade faster.
How to check your battery health before deciding
Your iPhone tells you exactly how degraded the battery is. Go to Settings, tap Battery, then Battery Health & Charging. You will see "Maximum Capacity" — this is the percentage of the original battery charge your phone can now hold. If it shows 80 percent or lower, the battery has aged significantly. If it shows 70 percent or lower, replacement is overdue.
The same screen shows "Condition" — Apple will say either "Normal" or "Service Recommended." If it says "Service Recommended," Apple is telling you the battery should be replaced. You do not need to wait for the percentage to drop further. Some older iPhones may also show "Poor Condition," which means the battery is failing and replacement is urgent.
When degradation becomes a daily problem
Battery degradation is gradual, so the moment to replace is different for everyone depending on how you use your phone. If you use your iPhone lightly — mostly texting, email, and occasional browsing — you might get four years before the battery becomes bothersome. If you use it heavily for video, gaming, or navigation, two years is more realistic.
The real test is whether the battery meets your actual needs. If you work away from outlets all day and your phone dies by 3 p.m., replacement makes sense even if the maximum capacity is still 75 percent. If you are near a charger most of the time, you can tolerate lower capacity longer. The point is not to hit a magic number but to replace the battery before it stops being reliable.
Cost and where to get replacement
Apple charges $69 to $99 for battery replacement depending on your iPhone model, with newer models costing more. The replacement takes one to two hours at an Apple Store if you have an appointment, or longer if you walk in. You can book an appointment through the Apple Support app or on Apple's website.
Authorized Apple repair shops — usually carriers like Verizon or independent certified repair centers — charge the same price and use genuine Apple batteries. Third-party repair shops often charge $30 to $50 less but may use aftermarket batteries that degrade faster or do not perform as well. Replacing the battery yourself is possible with a kit from iFixit or Amazon, but it requires opening the phone, risks damaging the screen or other components, and voids your warranty if anything goes wrong.
What happens if you ignore a failing battery
A degraded battery does not suddenly explode or catch fire — that is extremely rare. What happens instead is that your phone becomes unreliable. It shuts down without warning, even when the battery percentage shows 30 or 40 percent. You miss calls and messages because the phone powered off. You lose unsaved work. If you rely on your phone for navigation or communication, an unexpected shutdown is a real problem.
Over time, a very old battery can also swell slightly, which can push the screen or back panel out of alignment. This is a sign the battery should have been replaced months earlier. Swelling is rare but a reason to stop using the phone and get it serviced when ready.
Battery replacement versus buying a new phone
If your iPhone is three years old or newer and otherwise works well, battery replacement is almost always cheaper than a new phone. A $79 battery replacement extends the life of a phone that cost $800 or more. If your iPhone is five years old or older, the decision depends on whether other parts are failing — if the screen is cracked, the camera is broken, or the phone is slow, replacement may make more sense than pouring money into repairs.
Apple also offers trade-in credit if you do buy a new phone, which reduces the actual cost. But if the only problem is the battery, replacement is the practical choice.
How to extend battery life between replacements
You cannot stop a battery from aging, but you can slow it down. Avoid letting the phone drain completely to zero percent regularly — this stresses the battery. Avoid leaving it plugged in overnight constantly; modern iPhones have Optimized Battery Charging, which you can turn on in Settings > Battery > Battery Health & Charging. This feature learns your charging patterns and slows charging to 80 percent until you need the phone, reducing wear.
Keep your phone cool. Heat degrades batteries faster, so avoid leaving it in hot cars or direct sunlight. Use a case that does not trap heat. These steps will not prevent replacement forever, but they can add six months to a year to battery life.
Frequently Asked Questions
Can I replace just the battery or do I have to replace the whole phone?
You can replace just the battery. Apple and authorized repair shops can swap out the battery while keeping everything else on your phone intact. Your data, apps, and settings stay exactly as they are. The process takes one to two hours.
Will replacing the battery affect my warranty?
If you get the battery replaced at Apple or an authorized repair shop, your warranty is not affected. If you use a third-party repair shop or replace it yourself, you may void your warranty on other components if something goes wrong during the repair.
What is a charge cycle and how do I know how many I have?
One charge cycle means draining your battery from 100 percent to zero and back to 100 percent. You do not have to do this in one day — if you charge from 50 to 100 percent twice, that counts as one cycle. Your iPhone does not display total cycles, but you can estimate: if you charge once daily, you complete about 365 cycles per year.
Is it normal for my iPhone to get hot during charging?
Slight warmth is normal, especially with fast charging. Heat above what you would expect — too hot to hold comfortably — can indicate a battery problem. If your phone gets very hot during normal use or charging, have the battery checked before it fails unexpectedly.
Should I replace the battery before it gets really bad?
Yes. Replacing the battery when maximum capacity is 80 to 85 percent is easier and cheaper than waiting until it is 50 percent and the phone is shutting down constantly. Early replacement prevents the frustration of unexpected shutdowns and keeps the phone reliable longer.