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Is charging your phone overnight bad? 5 ways to improve battery life

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  • 8 min read

Every time you turn on your smartphone, a series of chemical reactions occur, and your device comes to life. These reactions occur in your devices’ Lithium-ion battery, a battery technology that has made handheld electronics possible.

Although Lithium-ion batteries have revolutionised the electronics industry, they are not perfect yet, and with every charging cycle, they lose the amount of charge they can hold.

In addition to this, your charging habits can also impact your devices’ battery life. So what is the best way to charge your device, and does charging it overnight degrade its capacity over time?

This article will be looking at all there is to Lithium-ion batteries and if connecting them to a charger overnight can degrade their performance.

Also read: What to do if you drop your phone in the water? Here are 4 ways to dry it

How do Lithium-ion batteries work?

Before understanding what is best for your battery, it is important to understand how they work.

Any battery you use is made of two parts, the Anode and the Cathode. In the case of a Lithium-ion battery, the Anode is made of graphite, and Lithium atoms are placed inside its crystalline structure.

The Cathode is made of metal oxides, and in most cases, this oxide uses Cobalt. The electricity which powers your mobile phone is created by the movement of electrons between these two terminals.

In addition to this, the two terminals have an electrolyte between them which is made of organic matter and has ionic Lithium salts inside it. This electrolyte enables the movement of ions between the two terminals.

During discharge, the lithium atoms in the graphite sheets lose electrons to become Lithium-ions. These electrons then make their way to the Cathode passing through the electronic circuitry of your device, powering it up. At the same time, Lithium-ions move from the Anode to the Cathode through the electrolyte and get trapped inside the Cobalt oxides.

When you charge your device, the charger pulls electrons from the Cathode back to the Anode. Due to this, the Lithium-ions also move back to the Anode and combine with the electrons to form Lithium atoms.

So if you look at it, the capacity of a Lithium-ion battery depends on the number of Lithium atoms that can provide free electrons. Therefore, any reaction which consumes Lithium-ions or atoms degrades its charging capacity.

Also read: Should you sleep next to your phone? Side effects and solution

Why do Lithium-ion batteries lose capacity?

If the above process works perfectly, a Lithium-ion battery would work forever, but due to some unwanted reactions, the Lithium-ions get consumed, reducing your batteries capacity.

Some of the reasons for the consumption of Lithium-ions and the degradation of capacity are as follows

  • Solid electrolyte interface: When the Lithium-ions move from the Cathode back to the Anode during charging, the Lithium-ion combines with the organic solvents to create solid electrolyte interfaces that irreversibly consume Lithium-ions.
  • Capacity: Looking at the data given above, we can see that keeping devices at full capacity can also reduce the battery’s capacity. In addition to this, completely discharging your battery can also harm its capacity. If a battery is kept in a completely discharged state, then the Lithium-ions at the Cathode combine with oxygen to form Lithium oxides which can degrade its capacity.
  • Temperature: Storing the battery at high temperatures can also degrade its performance.

The data given below shows how the retention capacity of Lithium-ion battery goes down as temperature increases.

Temperature40% charge100% charge
0°C98%(after 1 year)94%(after 1 year)
25°C96%(after 1 year)80%(after 1 year)
40°C85%(after 1 year)65%(after 1 year)
60°C75%(after 1 year)60%(after 3 months)
Estimated recoverable capacity after storing Lithium-ion batteries for one year at various temperatures.
Source: Battery university

Also read: How old is my Phone? 6 ways to figure it out

What happens when you charge your phone overnight?

Contrary to popular belief, you cannot overcharge the Lithium-ion battery on your smartphone. They have specialised circuitry, which prevents your phone from over changing. Therefore when you charge your phone overnight, it stops charging your battery when it reaches full capacity.

The battery management system then directs the power from the charger to the device and not the battery. Due to this, the battery losses power over time and needs to be charged again. So when you connect your device to a charger overnight, it keeps topping up the battery to 100 per cent repeatedly.

This repeated charging of your battery increases its temperature and keeps the battery at 100 per cent as well. If you look at the data given above, you can see that Lithium-ion batteries degrade more when kept in such conditions.

In addition to this, modern smartphones use fast charging technology to charge phones quicker by using more voltage. This further elevates the temperature of your phone and causes more damage when connected to the charger overnight.

Fast charging uses intelligent charging adapters that vary the voltage concerning the battery’s temperature to protect it. That said, it takes the battery to a higher temperature in lesser time, causing more damage to the battery.

The main problem with keeping your phone connected to a charger overnight is that it becomes a habit. So if you charge your phone overnight for a year, it stays connected to the charger for a period of 4 months and keeping a battery in such stressed situations causes the battery to degrade over time.

In addition to this, using protective covers while charging your device is also a bad practice. The covers heat up during the fast charging phase and keep the phone in a heated environment for a long period of time.

Also read: Does excessive gadget usage cause sleep inconsistencies?

How to improve your phone’s battery life?

Although Lithium-ion batteries are not perfect and their degradation is inevitable. You can improve their life by following good charging habits. A few tips for improving your smartphones battery life are given below.

Is charging your phone overnight bad? 5 ways to improve battery life
  • Charge your phone in a cool environment: High temperatures are your batteries biggest enemies. So to solve this problem, you can charge your phone by removing its protective case and not keeping it under your pillow while charging. A temperature range of 16 to 35 degrees is optimum for charging your phone.
  • Prevent charging at extreme battery conditions: Do not wait for your device to discharge completely before charging it. Instead, charge it when it is at 20 per cent. In addition to this, there is no need to charge your device to 100 per cent, and you can stop charging at 80 per cent.
  • Enable Airplane mode while charging: If you stress your phone while charging, it will generate a lot of heat. This heat can be awful for your batteries condition. Therefore, if you want to prolong your battery life, charge it in Airplane mode as it keeps your phone in a low-stress state.
  • Use slow chargers: If you have the time, you can use a regular charger rather than your fast charger while charging your device. A fast charger pumps a lot of power into your battery, degrading it faster.
  • Use authentic charging accessories: Using proper charging accessories to charge your devices is quintessential. Using cheap knock offs to charge your device can cause a lot of damage. Most manufacturers use proprietary technologies to charge their devices, and unverified third party manufacturers use cheap wires and current limiting systems, which can damage your device.

Lithium-ion batteries bring your electronics to life, and if you want to use them for a long time without damaging the batteries, you have to charge them with care. That said, if you can’t give up the habit of charging your phone overnight, you can buy a smart switch that can be configured to turn off after a certain duration.

Also read: How to unlock your Android smartphone with a broken screen?

Nischay Khanna

Nischay Khanna

A tech enthusiast, driven by curiosity. A bibliophile who loves to travel. An Engineering graduate who loves to code and write about new technologies. Can't sustain without coffee. You can contact Nischay via email: