An iPhone that goes dark in the middle of a call, or shuts down with plenty of charge still showing, is hard to trust. If you're asking why does my iPhone keep turning off, my first suspect is the battery, even when the percentage looks fine. Cold weather, a heavy update and a software loop come next, and a few free checks tell you which one you have. This guide walks through them in the order I'd check them, with notes for the iPhone 17, iPhone 16 and iPhone 14.
Key Takeaways
- An aging or cold battery can shut an iPhone down with charge left, and Apple says that shutdown protects the phone's parts.
- Check Battery Health in Settings first for the battery's maximum capacity and whether Apple recommends a replacement.
- Warm a cold phone up, and give it a day after a major iOS update.
- If it keeps turning on and off, force restart it, then use recovery mode and try Update.
- A worn battery needs replacing, and Apple's one-year warranty covers a defective battery.
Why does my iPhone keep turning off with battery left?
Most people expect a phone to die at 0 percent. An iPhone can switch off before that, and the reason is peak power, not the number in the corner.
A battery's impedance can rise as it chemically ages, and Apple says it also rises for a while when the charge is low or the phone is cold. When the phone needs a burst of power, a battery with high impedance lets its voltage drop further. If it drops too far, the iPhone performs a shutdown to protect its electronic components. Apple calls this shutdown intentional from the device's side, even though it feels random to you.
Apple says shutdowns are more likely at a low charge, a higher chemical age and in the cold. If your phone tends to switch off outdoors in winter, late in the day or after a few years of use, peak power is my first guess.
Check Battery Health first
Where to find it On iPhone 15 and later, Settings > Battery > Battery Health. On iPhone 11 to 14, Settings > Battery > Battery Health & Charging
In my view, this screen is the fastest way to confirm a battery problem. It shows the battery's maximum capacity compared with when it was new, and whether Apple recommends a replacement. On iPhone 15 models and later, it also shows the cycle count.
What it says about shutdowns depends on the model. On the iPhone 11 and later, Apple says a built-in system is automatic and always on, managing performance as the battery ages, so there's no switch to look for. On the iPhone 6 through iPhone XR, the screen can say the phone "has experienced an unexpected shutdown because the battery was unable to deliver the necessary peak power," with an option to turn performance management off. On those phones I'd leave performance management on until the battery is replaced.
Apple's battery and performance guide explains the messages on this screen. If you see "Your battery's health is significantly degraded," Apple says a replacement battery restores full performance and capacity, which no setting can do. Our guide on how to make phone battery last longer helps a healthy battery go further, but it can't bring a worn one back.
Warm up a cold iPhone
Where to find it Bring the phone indoors and let it warm up before you rely on it
Apple designs iPhone for use between 32 and 95 degrees Fahrenheit. Below that range, battery life can drop for a while, and Apple says very cold conditions could cause the phone to turn off. Battery life returns to normal once the phone is back in warmer air.
Heat is the other half. Apple warns against leaving an iPhone in a parked car, where temperatures can climb past even the 113 degrees Fahrenheit Apple gives as the limit for storing it, and says very hot conditions can permanently shorten battery life. If your iPhone only shuts down on ski days or winter walks, I'd keep it in an inside pocket and carry a small battery pack. If you're packing for a trip, our guide to iPhone settings for international travel covers the rest of the prep.
Update iOS
Where to find it Settings > General > Software Update
If the battery checks out, software is my next suspect, and updates are where Apple ships its bug fixes. Apple calls automatic updates the best way to get its features, security updates and bug fixes, so turn them on in the same menu.
One catch is worth knowing. Apple says an iPhone can feel warmer when it completes a software update, particularly a major release, and also while you set it up or restore it from a backup. That's normal, and the phone cools once the process is done. If shutdowns started the day you updated, I'd give the phone a day on the charger before deciding something is broken.
Why does my iPhone keep turning on and off?
Where to find it On an iPhone with Face ID, press volume up, then volume down, then hold the side button until the Apple logo appears
A phone that restarts over and over, flashing the Apple logo and going dark again, is stuck in a loop. Start with a force restart, using the three button presses above. Apple says the logo can take longer than 10 seconds to appear, so keep holding. If it won't turn on at all, Apple's advice is to charge it for one hour and try again.
If it still loops, the Apple logo stays on screen for several minutes with no progress bar, or it keeps starting up to Recovery Assistant, use recovery mode. Connect the iPhone to a computer and open the Finder on a Mac or the Apple Devices app on a PC. Do the same button presses, holding the side button until the "Connect to computer" screen shows. When the Update or Restore choice appears on the computer, Apple says to try Update first. Restore reinstalls iOS and erases all your data, so it's the last resort.
In my view, the answer to why does my iPhone keep turning on and off is usually software that can't finish loading or a battery that can't hold up. If recovery mode fails too, it's time for a repair.
Why does my iPhone 17 keep turning off?
Where to find it Settings > Battery > Battery Health
The iPhone 17 came out in September 2025, so even the first ones are only about a year old. A battery that young shouldn't have much chemical age, which is why I look at other causes first. Is the phone very cold or hot? Did it just finish a major iOS update, a setup or a restore from a backup? Apple says those make a phone run warm and that it cools once the process is done.
Apple designs the batteries in the iPhone 15 and later to keep 80 percent of their original capacity at 1,000 complete charge cycles under ideal conditions. Check Battery Health anyway. If it shows close to 100 percent and the phone still shuts down at normal temperatures, I'd say that points away from wear. A new phone that does that deserves a call to Apple, and if it's still inside the one-year warranty, a defective battery is covered.
Why does my iPhone 16 keep turning off?
Where to find it Settings > Battery > Charging
The iPhone 16 arrived in September 2024, so the first ones are now about two years old. Its battery carries the same rating of 80 percent at 1,000 complete cycles under ideal conditions, and its Battery Health screen shows the cycle count. If you use a full battery's worth every day, that's about 730 cycles in two years. Compare your count with 1,000 to see how far along yours is.
On the iPhone 15 and later you can set a charge limit between 80 and 100 percent, and Apple offers it to improve battery lifespan. The trade-off is that you start each day with less in reserve, and Apple says shutdowns are more likely at a low state of charge. If your iPhone 16 dies late in the day, I'd set the limit to 100 percent for a week and see if the shutdowns stop.
Why does my iPhone 14 keep turning off?
Where to find it Settings > Battery > Battery Health & Charging
The iPhone 14 came out in September 2022, and Apple stopped selling it in February 2025, so every one bought new from Apple has some age on it. Apple designs the batteries in the iPhone 14 and earlier to keep 80 percent of their original capacity at 500 complete charge cycles under ideal conditions, half the rating of the newer models. At about one cycle a day, that's under a year and a half of use.
That makes a worn battery my first answer to why does my iPhone 14 keep turning off, especially when it happens in the cold or at a low charge. Open Battery Health & Charging and read the maximum capacity and whether a replacement is recommended. If capacity is below 80 percent and you have AppleCare, Apple says it will replace the battery for no extra charge. Either way, I think a new battery is the fix, and money well spent on a phone this age.
When to book a battery replacement
Apple's one-year warranty covers a defective battery, but it doesn't cover a battery that wears down from normal use. Outside the warranty, Apple offers battery service for a charge. For most people, Apple says the safest repair is from a provider with certified technicians using genuine Apple parts, such as Apple or an Apple Authorized Service Provider, and its Independent Repair Providers can get genuine parts too. It also says only a trained technician should replace an iPhone battery.
Book the repair if Battery Health says the battery is significantly degraded or recommends a replacement, or if the phone shuts down at normal temperatures with a healthy battery. In my view, that second case points to a different fault, and it's one for Apple to diagnose. My rule is to back up before any repair, and Apple's own update steps start with a backup too. Our guide on how to back up photos covers the free options.
The Five-Step Shutdown Check
My advice is to work through this list in order, since the first three steps cost nothing.
- Open Battery Health and read the maximum capacity and whether a replacement is recommended.
- Note when it happens. Cold, a low charge and an old battery all point to peak power.
- Install the latest iOS update, then give the phone a day.
- If it loops or won't turn on, force restart it and charge it for an hour, then use recovery mode and try Update.
- Book a battery replacement when Battery Health says the battery is worn.
In my view, the answer to why does my iPhone keep turning off is usually waiting on the Battery Health screen. More fixes live in our phone secrets guides.
FAQs about an iPhone that keeps turning off
- Does AppleCare cover a worn battery?
- Apple says AppleCare will replace the battery for no extra charge if its capacity drops below 80 percent. The one-year warranty covers a defective battery but not normal wear.
- Why does my iPhone keep restarting by itself?
- In my view, a loop of restarts usually means iOS can't finish starting or the battery can't keep up. Force restart it, charge it for an hour if it won't turn on, then try recovery mode and choose Update.
- Can heat make my iPhone turn off?
- Heat can shut parts of it down. Apple says a phone that gets too warm can dim or black out its display and switch off some features for a while, and in extreme conditions the device might become temporarily disabled.
- Why does my iPhone keep turning off after an update?
- Apple says an iPhone can feel warmer after a major update and calls that normal. I'd give it a day, and if it keeps shutting down after that, check Battery Health and install any newer update.
- How do I stop my iPhone from turning off?
- Check Battery Health, keep the phone warm and charged, and install updates. If the battery is worn, replacing it is the lasting fix.
- Will my iPhone charge if it's too cold?
- It might not. Apple says a phone that gets too cold might not charge or could stop charging, and the Lock Screen can show a Charging On Hold message until it's back to a normal temperature.
- Will I lose my data if my iPhone keeps turning off?
- The checks in this guide don't erase anything, with one exception. Restore in recovery mode erases all your data, and Apple says to try Update before it.
- Is a new battery worth it for an older iPhone?
- For a phone that shuts down because its battery is worn, I think it is. When battery health is significantly degraded, Apple says a replacement battery restores full performance and capacity.
