Does Charging Your Phone Overnight RUIN the Battery?

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Does charging your phone overnight RUIN the battery

Does charging your phone overnight ruin the battery? Let’s dig in and take a look.

Smartphones can charge within two hours. So people worry about overcharging their phones overnight. They think that overnight charging can ruin their devices. This means that many people unplug their power cables before going to bed.

Yet there is another category of people who have the opposite opinion. They believe that overcharging cellphones does not affect the batteries.

In the past, most cellphone manufacturers warned not to overcharge their devices. They recommended that you stop charging at 100%.

But technology has advanced in the last decade. And most modern devices contain a chip that stops charging at 100%.

Many of these warnings regarding nocturnal charging are, in fact, superfluous. Most modern cellphones feature a fast charger: the charger recharges the battery double quick and once the cellphone is fully re-charged the charger automatically stops.

Still, many sources still argue that you shouldn’t charge your cellphone at 100%. To explain this mystery let’s have a look at the supposed reasons why you shouldn’t recharge the mobile phone overnight.

Lithium-ion Battery

As most of us know, cellphones contain a rechargeable lithium-ion battery.[1] These batteries recharge faster than traditional batteries.

Modern smartphones recharge the battery up to 80% in minutes. The remaining 20% takes a little longer to recharge.

Modern devices often have several applications running in the background. These include emails, messages, socials, and weather apps. So the charge diminishes. This is why many people consider overnight charging a necessity.

Mobile Apps

Still, we know that the charge cuts when it reaches 100%. But with constant app updates, the charger continues to add the bit of charge consumed.

In this situation, the cellphone stays between full charge and a little below. This increases the battery temperature for a prolonged period. And this can reduce its capacity. You can, of course, avoid this problem, if you turn the phone off while you sleep.

Another reason not to recharge overnight is the lifespan of rechargeable batteries. The capacity of rechargeable batteries is finite. And over time, it reduces with extensive use.

So the batteries used in mobile devices are in constant decay from the moment they’re first used. The constant recharging of mobile phone batteries results in the loss of their capacity.[2]

Battery Lifespan

As the lifespan of the battery reduces, so does the speed with which it accepts the charge. So with every cycle of charging, we increase the amount of time that a mobile phone spends with the charger. In this sense, overnight charging of mobile devices DOES reduce battery life.

And by charging overnight, we keep our phones on charge for three to four months per year.

This constant discharging and recharging increases the number of cycles of every recharge. This ends the battery life sooner.

There is a way to reduce the number of recharge cycles we need. Researchers recommend NOT waiting until the device is close to 0% before recharging.[3]

Recharging cycles

The reason? Charging an empty discharged battery increases the number of recharging cycles. This ultimately reduces the battery life and its capacity.

The best time for a charge, as recommended by battery experts, is when your charge is around 35-40% percent. This won’t consume a full recharge cycle, so saves the battery life.

One of the main issues with Li-Ion batteries is that they are temperature sensitive. Their charge and output efficiency vary depending on the temperature of the battery.

The only way that li-ion batteries can handle extra incoming current is by dissipating energy as heat. This increases the battery temperature and causes gases within the battery structure. In extreme cases, this can result in the battery rupturing or exploding.

But the latest advances in battery tech largely end the threat of overheating during the night.


The main time overheating can still be an issue is with the use of third-party chargers. These are often cheaply made and may not conform to appropriate safety standards. And they are probably not compatible with the cellphone and its energy needs. In these cases, the threat of overheating during overnight charging is real.

Moreover, for overnight charging so-called ‘fast chargers’ are not recommended. This is because they can cause overheating, thus reducing the lifespan of the battery.

For the modern smartphone, overnight charging doesn’t cause any damage. But this is only if you use the original charger supplied by the manufacturer.

Does charging your phone overnight ruin the battery – the VERDICT

However, any and all charging ultimately eats into the lifespan of the battery. So, by following the instruction above and generally making wise choices with your use of the cellphone, you can manage the decline and squeeze the maximum possible use from your trusty battery.

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Steve Brown


Steve is a gadget enthusiast who's always been intrigued by batteries. The founder and editor of Battery Chargers Info, he's assembled a group of like-minded experts to cover every facet of portable power His aim is to help you learn more about your favorite gadgets and their batteries so you can maximize both their performance and their life. Follow him on Twitter: @batterycharge1

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