Why Your Phone Dies in the Cold and How to Stop It

A phone that drops from 30% to nothing on a frosty platform has not lost its charge for good. Lithium-ion batteries deliver power less readily when they are cold, so the phone sees a voltage dip and shuts down to protect itself. Warm it up gently and most of that charge comes back. Apple, for one, says the drop in battery life in very cold conditions is temporary.

It happens every winter: a walk to the bus stop in sub-zero temperatures, a photo of the frost, and the screen goes black. The good news is that this is normal behaviour and rarely a sign of a failing battery. The trick is to keep the phone in its comfortable range and to know what to do when it does give up.

What the manufacturers say about temperature

Apple's support page on hot and cold conditions says iPhone and iPad are designed for use where the ambient temperature is between 0°C and 35°C, and should be stored between -20°C and 45°C. Below that operating range, the phone may change its behaviour to regulate its temperature, and some features may be temporarily disabled.

Apple's battery performance page adds that the ideal comfort zone is 16°C to 22°C. It notes that in a very cold environment you may see a decrease in battery life, but the condition is temporary, and performance returns to normal once the battery is back within its usual range. Heat is the real long-term enemy: Apple says temperatures above 35°C can permanently damage battery capacity.

Android phones use the same battery chemistry and behave in much the same way, even if manufacturers word their guidance differently.

Why the percentage lies in the cold

A battery's percentage is an estimate based partly on its voltage. When the cells are cold, the chemical reactions inside slow down and the battery cannot deliver current as easily. The voltage sags, especially when you ask for a burst of power by opening the camera or turning on the torch. The phone reads that dip as a nearly empty battery and switches off to avoid damage.

An older battery makes this worse. As a battery ages, its internal resistance rises, so the voltage drop under load is larger. If your phone only started shutting down in the cold this year, its battery health may be part of the story. Our guide to smartphone battery health explains how to check it in settings.

Keeping it warm without overdoing it

• Inside pocket, not outside. A jacket's inner pocket, close to your body, keeps the phone several degrees warmer than a coat pocket or a bag.
• Use a case. Even a slim case adds a little insulation and cuts down how quickly the phone cools. Folio cases, which cover the screen, help most. Our case guide compares the types.
• Limit time out in the open. Take the photo, then put the phone away rather than holding it in a bare hand at the bus stop.
• Use earbuds or a smartwatch for calls and directions on a long walk, so the phone stays tucked away.

Condensation: the hidden winter risk

Bringing a very cold phone straight into a warm, steamy room, like a café or a kitchen with the kettle on, can cause condensation to form on and inside it. For the same reason, avoid charging a phone that has just come in from freezing conditions. Give it time to reach room temperature in a pocket or bag first, then plug it in.

If you see misting on the camera lens or screen, let it clear by itself. Do not use a hairdryer. Our article on cleaning your phone safely covers wiping off moisture without pushing it into the ports.

If the phone has already switched off

1. Put it somewhere warm but not hot, such as an inside pocket, for 15 to 20 minutes.
2. Try switching it on. In many cases it will show a much higher percentage than you expected.
3. If it will not start, connect it to a charger once it has reached room temperature, and leave it for a few minutes before pressing the power button.

If your phone keeps shutting down even indoors at room temperature, or the battery health reading is low, it is time to look at a battery replacement rather than blaming the weather.

Charging in winter

Charging a battery while it is very cold is harder on it than charging it at room temperature. Phones manage this automatically by slowing down or pausing charging, but you can help:

• Charge indoors, not in an unheated car on a frosty morning.
• Take a power bank on long winter days out, and keep that warm too, as it uses the same battery chemistry. If you are flying, check our guide to this year's power bank rules for flights.
• Use a decent USB-C charger and cable, which give the phone's own charging control the best chance to work properly.

Settings that buy you time outdoors

When you know you will be out in the cold for a while, such as on a winter walk or at a bonfire night event, reduce the demand on the battery:

• Turn on Low Power Mode or Battery Saver before you head out, not when the battery is already low.
• Download maps for offline use, so the phone is not constantly searching for signal on a hillside.
• Turn screen brightness down and shorten the auto-lock time.
• Close the camera when you are not taking photos; it is one of the most power-hungry apps.

For long days in remote places, it is still worth carrying a paper map or telling someone your route. A phone is a brilliant tool, but in real cold it should not be your only plan.