How to look after your iPhone battery in hot weather

Keep your iPhone out of hot places and avoid charging it while it is hot. Apple says iPhone works best at ambient temperatures between 0°C and 35°C. In hot weather, the parked car, direct sun and a hot charging spot matter most, and a few built-in settings take care of the rest.

Why does heat matter for an iPhone battery?

Apple describes 16°C to 22°C as the ideal comfort zone for iPhone. It warns that ambient temperatures above 35°C can permanently damage battery capacity, which means a full charge lasts for less time. Charging in high temperatures can add to that damage, and even storing a battery somewhere hot can harm it for good.

Cold works differently. In a very cold place battery life can drop for a while, then it returns to normal once the phone warms up. Heat is the one to plan for, because its effect can last.

Which everyday habits protect your battery in the heat?

• Never leave it in a parked car. Apple advises storing iPhone between minus 20°C and 45°C, and says temperatures in parked cars can go beyond that range. Take it with you, even for a short stop.
• Keep it out of direct sun. Apple lists leaving the phone in direct sunlight for a long time among the conditions to avoid. At the beach or by the pool, keep it in a bag or in the shade, and do not leave it on a sunny dashboard.
• Charge it somewhere cool. A room at normal temperature is the right place. Avoid charging in the sun or in a hot car.
• Take the case off if it gets hot while charging. Apple notes that some styles of case can hold extra heat in while the phone charges, and that heat can affect battery capacity.
• Give heavy tasks a break in the heat. Apple mentions GPS and maps in a car, graphics-heavy games and long camera sessions in hot conditions or direct sun. Pause, move into the shade and let the phone cool.

Which settings help the battery every day?

Optimized Battery Charging. It is on from the moment you set up your iPhone. The phone learns your daily routine and, when it expects to stay on the charger for a long time, waits to finish charging so it spends less time fully charged. On iPhone 15 models and later, you can also choose a charge limit in Settings > Battery > Charging. On iPhone 14 models and earlier, the switch is in Settings > Battery > Battery Health & Charging. Apple notes that turning charging optimisations off can increase wear on the battery.

Low Power Mode. When the battery runs low, turn it on in Settings > Battery > Power Mode on iPhone 15 and later, or in Settings > Battery on iPhone 14 and earlier. You can also tap the battery icon in Control Center. It reduces screen brightness and turns off background tasks such as automatic downloads and Background App Refresh.

Software and screen. Keep iOS up to date in Settings > General > Software Update. Use Auto-Brightness or a lower brightness level, and use Wi-Fi when you can: Apple notes that a Wi-Fi connection uses less power than a cellular network.

What does a hot iPhone do to protect itself?

Some warmth is normal. Apple says an iPhone can feel warmer during setup, while restoring from a backup, during a software update, on a wireless charger, while streaming high-quality video and in games or camera apps. It cools down when the task ends.

If the inside of the phone gets too hot, iOS steps in to protect its parts. Charging may slow down or pause, the screen may dim, the signal may weaken for a while, and some camera features may switch off until it cools. A Lock Screen message may say that charging is on hold until the iPhone returns to normal temperature. If you are following directions in the car, spoken turn-by-turn guidance continues even while the screen is off.

If a temperature warning appears, follow Apple's steps: turn the iPhone off, move it somewhere cooler and out of direct sunlight, and let it cool down.

How should you store a spare iPhone?

For a phone you keep in a drawer, Apple recommends storing it about half charged and switched off, in a cool, dry place below 32°C. If it stays there longer than six months, charge it to about half again every six months.

How does 3ASH DEVICE check the battery?

Every pre-owned iPhone we sell is inspected before it is listed, with Phonecheck software and more than 80 checks, and the battery is tested as part of that inspection. Every pre-owned device also comes with a 12-month 3ASH warranty.

Frequently asked questions

Can I charge my iPhone overnight?

Yes. This is the situation Optimized Battery Charging is designed for: the phone learns when you usually unplug and times the last part of the charge, so it spends less time fully charged. Apple says the feature needs at least 14 days to learn your routine. Leave the phone on a cool surface, away from direct sun.

Why has my iPhone stopped charging on a hot day?

When the battery is too warm, iOS can put charging on hold and show a message on the Lock Screen. Charging resumes by itself once the temperature is back to normal. Move the phone somewhere cooler, and take it out of its case if the case feels hot.

Is it fine to leave my iPhone in the car for a few minutes?

It is better not to. Apple advises against leaving iPhone in a car, because temperatures in parked cars can exceed its storage range, and heat damage to the battery can be permanent.

Does a pre-owned iPhone need special battery care?

The same habits suit every iPhone, new or pre-owned: keep it out of the heat, charge it somewhere cool and leave Optimized Battery Charging on. We test the battery of every pre-owned device as part of our inspection, and each one comes with a 12-month 3ASH warranty.

When you are ready for your next iPhone, browse our pre-owned iPhone, compare the three conditions in the condition guide, or read how to check a used iPhone before you buy.