A new iPhone battery lasts two to three years under normal use
An iPhone battery degrades over time, and most people notice a real drop in performance between year two and year three. Apple designs its batteries to retain 80 percent of their original capacity after 500 full charge cycles — that is, 500 times from zero to 100 percent. In daily use, that usually means two to three years before the battery no longer holds a full day of charge.
How fast your battery degrades depends on what you do with your phone. Heavy use — constant video, gaming, or navigation — wears the battery faster. Light use stretches it longer. Temperature matters too: heat speeds degradation, so a phone left in a hot car or used while charging in direct sun will age faster than one kept cool.
You can check your battery's current health in Settings. Go to Settings > Battery > Battery Health & Charging, and look at the "Maximum Capacity" number. If it shows 80 percent or higher, your battery is still in good shape. Below 80 percent, you will start to notice the phone shutting down unexpectedly or struggling to run multiple apps at once.
Key Takeaways
- Most iPhone batteries last two to three years before they drop below 80 percent capacity and start to noticeably drain faster.
- You can see your battery's current health percentage in Settings > Battery > Battery Health & Charging on any iPhone running iOS 16 or later.
- Heavy use, heat exposure, and frequent fast charging all speed up battery degradation beyond the normal timeline.
- Once capacity falls below 80 percent, the phone may shut down unexpectedly even when the battery percentage shows 20 or 30 percent remaining.
What happens as your battery ages
As a battery loses capacity, it cannot hold as much charge. A two-year-old battery might only reach 85 percent of its original capacity, meaning a full charge gets you through less of the day than it used to. The phone's operating system tries to manage this by limiting performance — slowing down the processor slightly to reduce power draw — but you will still notice the phone drains faster.
Around 80 percent capacity, the phone starts to show real signs of age. Apps take longer to open. Multitasking becomes sluggish. The camera takes longer to launch. These slowdowns are intentional: Apple throttles performance to prevent unexpected shutdowns, which happen when the battery voltage drops too quickly under heavy load.
Below 70 percent capacity, unexpected shutdowns become common. Your phone might show 30 percent battery and then power off without warning. This is not a software glitch — it is the battery no longer being able to deliver the current the processor needs, even though chemical energy remains inside.
Factors that shorten battery life
Heat is the single biggest enemy of iPhone batteries. Lithium-ion batteries degrade faster at high temperatures. If you regularly use your phone while it is charging, leave it in a hot car, or use it in direct sunlight for extended periods, the battery will age faster than the two-to-three-year baseline. Even a few degrees of sustained heat can cut a year off the battery's lifespan.
Fast charging and wireless charging also speed degradation slightly, though the effect is smaller than heat. Charging from zero to 100 percent repeatedly is harder on the battery than charging from 20 to 80 percent. If you want to extend battery life, avoid letting the phone drop below 20 percent regularly, and unplug it once it reaches 100 percent rather than leaving it plugged in overnight.
Background activity drains the battery and generates heat. Apps running location services, checking email constantly, or syncing in the background all contribute. Turning off location for apps that do not need it, disabling background app refresh for apps you do not use often, and turning off push notifications for less important apps will reduce the workload on the battery and slow degradation.
When to replace your battery
You should consider a battery replacement once capacity drops below 80 percent and you notice the phone draining noticeably faster or shutting down unexpectedly. At that point, the battery is no longer reliable for a full day of normal use.
Apple offers battery replacement through its stores and authorized service providers. The cost varies by iPhone model but typically ranges from $50 to $70 for models older than the current generation. If your phone is still under warranty or covered by AppleCare+, the replacement may be covered at no cost. Out-of-warranty replacement usually takes three to five business days.
Third-party repair shops often charge less than Apple — sometimes $30 to $50 — but the quality of the replacement battery varies. Some use genuine Apple batteries, others use aftermarket batteries that may not last as long or perform as well. If you choose a third-party shop, ask whether they use original or aftermarket batteries before you commit.
How to slow battery degradation
Keep your phone cool. Avoid using it in direct sunlight for long periods, do not leave it in hot cars, and remove the case while charging if the phone gets warm. If your phone feels hot during normal use, close apps and let it cool down before continuing.
Enable Optimized Battery Charging in Settings > Battery > Battery Health & Charging. This feature learns your charging patterns and slows charging to 80 percent until you are about to use the phone, which reduces the time the battery spends at full charge — the state where degradation happens fastest. It extends battery lifespan by several months over the life of the phone.
Avoid letting the battery drop to zero regularly. Charging from 20 to 80 percent is gentler on the battery than charging from zero to 100 percent. If you use your phone heavily, charge it during the day rather than waiting until the battery is nearly dead.
Turn off features you do not use. Location services, Bluetooth, and background app refresh all consume power and generate heat. Disable them for apps that do not need them. In low-battery situations, enable Low Power Mode, which reduces performance and background activity to extend the time before the battery dies.
Battery life versus battery health
Battery health is the maximum capacity — how much charge the battery can hold. Battery life is how long the phone runs on a single charge. These are different things. A phone with 85 percent battery health might still last a full day if you use it lightly, but a phone with 70 percent health will probably not.
Battery health degrades predictably over time. Battery life depends on what you do with the phone. The same phone with 80 percent health might last a full day for someone who checks email and texts, but only eight hours for someone who streams video constantly. Check your battery health in Settings to know where you stand, but remember that your actual usage determines whether you need a replacement now or can wait a few more months.
Frequently Asked Questions
Can I replace the battery myself?
Apple does not sell batteries to consumers for self-installation, and opening the phone yourself will void any remaining warranty. If you want a replacement, you will need to go through Apple, an authorized service provider, or a third-party repair shop. Self-repair is technically possible but requires specialized tools and risks damaging the phone.
Does using Low Power Mode damage the battery?
No. Low Power Mode reduces performance and background activity to extend battery life, but it does not harm the battery itself. Using it regularly actually helps, because it reduces the overall workload on the battery and generates less heat.
Why does my iPhone shut down at 20 percent battery?
If your phone shuts down when the battery percentage is still 20 or 30 percent, the battery health has dropped significantly — probably below 70 percent. The battery cannot deliver enough current to power the phone at that moment, even though chemical energy remains. This is a sign you need a replacement soon.
Does charging overnight damage the battery?
Modern iPhones have Optimized Battery Charging, which stops charging at 80 percent until shortly before you wake up. If this feature is on, overnight charging is fine. If it is off, leaving the phone plugged in all night does cause some extra degradation, because the battery spends hours at 100 percent capacity. Turn on Optimized Battery Charging in Settings to avoid this.
Is a two-year-old iPhone battery still good?
It depends on use. Check Settings > Battery > Battery Health & Charging. If capacity is 85 percent or higher, the battery is still in good shape and should last another year or more. If it is below 80 percent, you will notice performance issues and should plan for a replacement within the next few months.