Is it safe to charge your phone overnight?

Many people put their phone on a charger before going to sleep so that they can start the next day with a full battery. Is this good, or is it better not to charge your smartphone when you lie on one ear?

Fact or fiction: Charging your phone overnight is bad

Thanks to the rise of fast charging, smartphone batteries are full faster and faster. Anyone walking around with a relatively new model can bring her or his battery from 0 to 100 percent in about 45 minutes to an hour. With some devices, this is even faster. Consider, for example, the OnePlus 10T, which only takes 20 minutes to do.

That’s where the first myth surrounding charging your phone overnight comes into play. It is not the case that smartphone batteries can ‘overcharge’. When 100 percent is tapped, the device stops drinking electricity. If the percentage falls to 99 percent, then something is added. This process continues until you wake up in the morning.

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Yet you regularly hear the advice to remove your smartphones from the charger as soon as the battery is full. This myth is probably so persistent because the advice used to be correct. Back then, telephones had older batteries that could indeed overcharge (with wear and tear as a result). Modern lithium-ion batteries do not have this problem. 

Risk of fire

It is therefore not the case that charging your phone at night is very harmful because the battery then ‘overflows’. However, some parties, including insurers and the fire service, advise against charging your device before going to sleep. This is mainly due to the risk of fire hazard.

Some devices get very hot during charging. The heat can (in rare cases) cause the phone to catch fire. This risk increases the moment you charge your phone under a pillow, for example, or put it under a pile of books. It also sometimes happens that people accidentally place their smartphone on the heating or a laptop while charging.

Charging a phone overnight is bad for the phone’s battery

There’s another reason why you might prefer not to charge your phone overnight. It sounds a bit crazy, but it’s better not to charge the battery to 100 percent. This leads to much more battery wear than when you charge to 70 or 80 percent, for example.

Lithium-ion batteries wear out much faster after 80 percent than before. This has to do with the chemical composition of a telephone battery, which thrives best between a charge percentage of about 20 to 80 percent. The video below shows how hard a lithium-ion battery wears when you fully charge the battery or completely discharge it (i.e. let it run to 0 percent).

Tips to keep your battery in tip-top condition

It is therefore bad for the lifespan to fully charge a smartphone battery. That said, the question is how concerned you should be about this. The long-term effect is probably not that bad.

If you wake up at night and see that the battery is full, it is of course best to unplug the charger from the socket. However, the effect should not be overestimated. It is not that your battery lasts for years longer if you always keep the percentage in the middle.

It is therefore best not to fully charge or discharge the battery if you want to work seriously with her or his phone battery. That is easier said than done because by default smartphones charge their batteries to 100 percent. If you don’t feel like it, you should remove the charger exactly around the 80 percent battery percentage.

Accu​Battery

AccuBattery is a handy app that helps with this. Not only does the program show the power consumption of your smartphone in great detail, but you can also set timers. Such a ‘charging alarm’ gives a signal when, for example, the battery is 70 or 80 percent full. AccuBattery is free but does contain ads. You can buy it by purchasing the premium version.

You can also approach it differently. Do you use a smart plug at home? Then set it so that the battery supply is cut off as soon as your smartphone battery is sufficiently full. For example, you can set the smart plug to switch off automatically 45 minutes after you start charging. This way you can still charge a phone responsibly at night.