Pourquoi la batterie de votre téléphone meurt-elle si rapidement?

Your Definitive Guide to Phone Battery Life

There is one battery you're always watching. Your phone battery.

How much do you know about it?

Your phone runs on a lithium-ion battery, and for a good reason. Li-ion batteries pack a lot of energy for their size and weight—and they can get really small. They also hold their charge when they're not being used. Lithium-ion batteries are compact, stable and energy dense.

But if you've had your phone for a while, it's probably not working as well as it used to.

Your phone battery is draining fast these days. It doesn't stay at 100 percent as long as it did last year, and it runs to 0 percent before you can get to a charger.

Sometimes your phone gets hot. Really hot.

Your phone's heat, the battery draining so fast — it's all connected.

Let's explain what's happening in your phone and show you how your phone's heat affects its performance.

We'll give you some new habits to help your phone battery last longer. First …

Why your phone is so hot

The short answer is electricity. You could be running a fancy virtual reality chat, installing the latest OS update or playing a game with 3D graphics.

Your phone gets so hot because it's moving a lot of electricity, either to process data, brighten the phone screen or recharge the battery.

Any of these can raise the temperature of your phone, which isn't good for your phone battery's overall lifespan.

Your phone is hot because it's processing data.

One of the big reasons your phone overheats is because it's processing a lot of information.

You see, computers create heat when they process data.

Deep in your phone, in the silicon and circuit boards, electricity is moving and shifting position. The more processing your phone is trying to do, the more heat it can generate. No system is perfect, so some electrons turn into heat instead of finishing a calculation or opening an app.

Now, anytime you tap your phone, you're using processing power. Swiping menus or scrolling through a car battery blog doesn't take much processing. That's hardly enough to warm up the central processing unit (CPU).

Heavy processing really heats up your phone.

Your phone may get hot when it's:

• Navigating a map with GPS
• Streaming a movie in high definition
• Running a video game with 3D graphics
• Running a photo editor
• Streaming a voice chat
• Downloading and installing a large app or operating system update
• Doing two or more of those at the same time

You can find your phone's processor by following the heat. Touch the back of your phone when you start anything that takes heavy processing. The first warm spot you find is probably the CPU.

Heat doesn't stay in one place. It radiates out. By the time your phone is hot in your hand, your phone's other components are already feeling the heat. To the screen, the battery, other circuits, the case, everywhere.

You can cool down your phone by cooling down how much work your phone is doing. Stop the game, voice chat or video. Or turn off background apps. You can even save some processes, such as updating your apps, for when you're not using the phone.

You can also follow some of these ideas below.

Your phone is hot because the screen is bright.

Think of a light bulb. The brighter it gets, the hotter it gets.

Now, your phone's manufacturer put a lot of thought into the screen you're poking right now. Your phone's touch screen is both the computer's primary input and its main display. It's interpreting electrical disturbances on the screen as input. At the same time, the graphics processing unit (GPU) is putting out instructions toward ultra-thin layers of crystal, filament, pixel grids and more. There's a lot going on. The ever-innovating engineers push the technology to be both more efficient and more sophisticated.

That said, the brighter your screen gets, the hotter it gets.

Phone screens, especially OLED (organic light-emitting diode or organic LED) screens, work so efficiently that you can make them blindingly bright. And at first it won't warm up your phone much. Give it five minutes. The screen will warm evenly. The rest of your device will get a few degrees hotter, too, because your screen covers one whole side of your phone.

Most phones have a setting for adaptive brightness. If it senses a bright environment (like a sunny day), your phone will brighten up the screen.

Unfortunately, sunny days are also warm. Warmth adds up.

Your Android phone gets hot because you spent 10 minutes trying to get the perfect selfie on a sunny day. Your iPhone is so hot because you're outside on a bright day watching YouTube. Your phone is hot because the sunlight from your window tricked the adaptive brightness into pumping up the screen's brightness to 100%, and you haven't noticed yet.

So, turn that screen brightness down.

Your phone battery will thank you (by lasting longer.)

Your phone is hot because it's recharging.

Recharging your phone battery moves a lot of electricity—and heat is a natural result.

Which is unfortunate because heat hurts your phone battery's long-term health. Fast charging generates even more heat.

Recharging your phone starts a process that separates lithium atoms from one layer of the battery to another, converting it back into lithium metal that you can then use for power. However, chemical processes aren't 100 percent efficient. A fraction of that electricity turns into heat. Usually, you don't feel much heat because lithium-ion batteries usually power small devices that need a low, steady charge.

However, the faster you recharge it or use its power, the hotter your phone battery will get.

Usually that heat will dissipate, either into the air, a solid surface or your hand. (Ouch!) If the heat can't escape (because it's insulated in your coat pocket or purse), then a li-ion battery will steadily overheat and start generating more heat than it can get rid of. That's called thermal runoff, and it's not good.

So keep your phone cool when you charge it.

Why your phone battery is draining so fast

If your phone battery is dropping from 80 percent to below 30 percent in a few hours,

Your lithium-ion battery has been damaged in some way, and your phone has apps that draw constant processing power.

There are two ways your phone battery can get damaged: heat damage or damage from being 100 percent or 0 percent.

Staying 100 percent charged and hitting 0 percent hurt your battery.

Li-ion batteries don't like being 100 percent charged or 0 percent empty. Those extremes damage the usable part of a li-ion battery, the lithium metal.

Your phone battery gets electricity from lithium metal merging with another material and losing some of its ions. When you charge it (sending ions back into the battery), the lithium returns to itself. The lithium can do this all day. The problem comes when it charges to 100 percent all the time, then molecules of it start to resist change. Worse is when your phone battery drops to 0 percent. Some of the lithium stays permanently bonded. The longer your battery stays low on charge, the more usable lithium you lose.

Heat can hurt your phone battery's anode.

Remember how moving electricity around causes heat? The anode is the part of the battery that receives new electricity when you charge it.

It's also where lithium-ion batteries face a particular weakness: anode fracturing.

The anode, receiving new electrons, warms up. Warm things expand. It returns to normal as it cools down. However, the more often the anode expands and contracts, the more likely it is to break.

The warmer your phone gets while charging, the more likely it is for microscopic cracks to form. Anode cracks make it hard to recharge the phone battery completely. The electricity has to find new paths around those cracks. And anode cracks are irreversible.

Scientists are hard at work searching for more durable materials that stand up to recharging more often.

Until then, keep your phone cool when charging it.

Phone apps add to its processing load (and the demands on its battery.)

A damaged li-ion battery won't discharge itself to 0 percent without help.

Phone apps you've added over time might be running in the background. Any amount of processing your phone does will draw power from the battery.

Plus, your phone needs power to run all of its signals and sensors. If an app is checking your GPS position, tapping the Wi-Fi, or checking on Bluetooth signals, those antennas are also drawing power from the phone battery.

Your regular cellular data signal is checking towers and position constantly.

Alone, one app in the background won't drain your battery quickly. However, a couple dozen processes will draw a healthy dose of power.

If your phone battery is healthy enough to give one.

Otherwise, keep your charger handy.

How to make your phone battery last longer

These guidelines and new phone habits will help you get more life out of your phone battery.

That said, you should consult your battery manufacturer's and phone maker's documentation to see what the typical lifespan of your phone battery is and what you can reasonably expect a year or two into using it.

1. Turn your phone off before it hits zero percent. Getting to zero percent is the biggest danger you have direct control over. When your phone hits 40 percent, get to a charger. If your phone battery drops to 20 percent, turn your phone off. Better safe than short-lived battery life. Once you get to a charger, it's safe to power up your phone again.
2. Unplug your phone at 90 percent. Hitting 100 percent might soothe your anxiety in some way, but your phone battery doesn't feel soothed. Hitting the hundred can chip away at your battery's health—ultimately making 100 percent mean less than you think.
3. Get comfortable with life between 80 percent and 40 percent. You live in this zone. Keeping your phone battery healthy isn't about using your phone less. Train yourself out of thinking you have to hit 100 percent or wait for it to die.
4. Unplug your phone before bed. Stop overnight charging. Just charge up before going to sleep. Some phone features try to calculate how to slowly charge your phone to avoid the damage this does to your battery. Make the whole thing easier on your phone and unplug it overnight.
5. Avoid heat when charging your phone up. Don't update apps, and turn off unused antennas such as Bluetooth, Wi-Fi or mobile data. Avoid any heavy processing when recharging your phone. If you can't avoid it, then …
6. Dissipate your phone's heat often. Put your phone in cool air. On a wood table or a thick stone cutting board. Set a warm phone in a place where it can cool down—and far from anything warm or insulating.
7. Update and install your apps when you're not charging. Just one heat-generating process at a time, please. Monitor your phone so you don't lose power at a crucial moment.
8. Manage your screen's brightness. Phone screens are scientific wonders. Turning up the light isn't the only way to make text more legible. Explore your display settings. See if text size, contrast boosting and adaptive colors let you take the brightness down a notch.
9. Learn from your battery usage stats. If screen brightness isn't your problem but background apps are, you'll see it in the battery usage stats. You can also find battery health apps to help you pinpoint anything that is draining your phone battery. However, only keep the apps you use.
10. Uninstall unused apps. A phone application may run without you opening it, and your phone definitely spends processing power updating it. If you're not using it, uninstall it. You may find a background power-hungry app draining your phone.