Heat does more damage to an iPhone battery than almost anything else, and the damage can be permanent. Here is how to protect your iPhone battery from heat, from a parked car to the charger on your desk.
The best temperature range for an iPhone battery is 62 to 72 degrees Fahrenheit (16 to 22 degrees Celsius). Using or charging an iPhone in ambient temperatures above 95 degrees Fahrenheit (35 degrees Celsius) can permanently reduce battery lifespan.
Hot Cars and Direct Sunlight Do the Most Damage
A parked car or a sunny windowsill pushes an iPhone past 95 degrees Fahrenheit faster than any other situation. Extended GPS navigation and long camera sessions in hot weather add to the load.
Once the phone gets too hot, it protects itself. Charging slows or stops, the display can dim or go black, the cellular signal weakens, the camera flash switches off for a while and apps run slower. Navigation may show a message that the iPhone needs to cool down.
Keep the iPhone out of direct sunlight and out of parked cars. Avoid using or charging it in hot environments for long stretches.
Setup, Updates and Wireless Charging Make an iPhone Run Hot
A battery warms up as it charges, and that heat counts against its lifespan. Charging in a hot room stacks the two together. Several everyday jobs also raise the temperature on their own.
- Setting up a new iPhone or restoring from a backup
- Installing a software update
- Wireless charging, including MagSafe wireless chargers
- Graphics-intensive or processor-intensive apps and games
- High-quality video streaming
Newer hardware helps, since the iPhone 18 Pro teardown showed a larger vapor chamber, but the same temperature limits apply.
Charge Limit and Optimized Battery Charging Cut the Time at 100 Percent
On iPhone 15 models and later, Optimized Battery Charging is turned on by default and reduces battery wear by cutting the time the iPhone spends fully charged. It holds the charge near 80 percent when it expects a long stretch on the charger, then finishes before you need the phone. It needs at least 14 days to learn your routine.
iPhone 15 models and later also have a Charge Limit. It caps charging anywhere from 80 to 100 percent in 5 percent steps, so an iPhone that sits on a charger all day can stop well short of full.
- Open Settings and tap Battery.
- Tap Charging.
- Choose a limit between 80 and 100 percent.
Even with a limit below 100 percent, the iPhone charges fully once in a while to keep its battery estimate accurate. The software can also hold charging at 80 percent on its own when the battery temperature goes outside the recommended range.
A Hot iPhone Should Be Turned Off and Moved Somewhere Cool
When an iPhone gets too hot, turn it off, move it out of direct sun to a cooler spot and give it time. A lock screen message saying charging is on hold means the phone is waiting to return to a normal temperature. Charging, including wireless charging, resumes once it does.
The normal operating range is 32 to 95 degrees Fahrenheit (0 to 35 degrees Celsius). Storage should stay between minus 4 and 113 degrees Fahrenheit (minus 20 to 45 degrees Celsius). For long-term storage, keep the iPhone about half charged.
Battery Health Shows the Damage Over Time
Maximum capacity in the Battery Health settings compares what the battery holds now with what it held when new. Batteries on iPhone 14 models and earlier are designed to keep 80 percent of their original capacity at 500 complete charge cycles under ideal conditions.
If battery health has dropped sharply, an Apple Authorized Service Provider can replace the battery to restore performance and capacity.
