Does Charging Your Phone Overnight Ruin The Battery?

There has been a lot of myths going around smartphones and one of them is charging your phone overnight ruins or damages the battery.

This is absolutely false. People spread these myths without knowing the capabilities of Lithium-Ion batteries which are used in smartphones.

Lithium-ion batteries are smarter than AA batteries and here’s how charging your phone overnight won’t cause any damage to your smartphone’s battery.

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What Are Lithium-Ion Batteries?

Every battery contains two electrodes and an electrolyte which acts as a conductor of ions from the negative electrode to the positive electrode to allow the flow of current.

In Lithium-Ion batteries, the Lithium ions move from the negatively charged electrode(Cathode) to the positively charged electrode(Anode) in the presence of an electrolyte to provide current or power to the smartphone.

lithium ion battery of smartphone

This power is consumed by the smartphone for different tasks and the battery of the smartphone gets discharged. When all the Lithium ions have traveled from the Cathode to the Anode then the Smartphone battery gets totally discharged and you are left with Zero Charge(0% Charge).

When you plug your phone to charge then the electricity completes the circuit and forces the Lithium ions to now move from Anode to the Cathode. This causes your battery to get charged. Once all the Lithium ions have moved from the Anode to the Cathode then your battery gets Fully Charged(100% Charge).

Unlike AA batteries the Lithium-Ion batteries can recharge with the help of electric current. Hence, they are known as Rechargeable Batteries.

Lithium-Ion batteries in smartphones can be removable or non-removable.

Charging and Discharging Cycles of Lithium-Ion Batteries?

Lithium-Ion batteries have a certain number of charging and discharging cycles before it loses most of the charge and becomes unusable. You have to replace the battery once this happens.

charging-discharging cycle of lithium ion battery

A Full Charging Discharging Cycle occurs when the battery goes from 100% Charge to 0% and then 0% to 100%.

When the battery goes from 100% to 0% charge then it is called Full Discharging Cycle. Similarly, when the battery goes from 0% to 100% charge then it is known as Full Charging Cycle. The full cycle is known as One Charge Discharge Cycle.

If you repeat the cycle above once more then you will get Two Charge Discharge Cycles.

An Average Lithium-Ion battery has a life of about 300 – 500 Full Charge Discharge Cycles. This translates to a life of around 2 to 3 years.

If your battery charge drains from 100% to 50% and then you plug in your smartphone and charge it from 50% to 100% then it is known as Half Charge-Discharge Cycle. If you repeat the cycle again then you will get One Full Charge-Discharge Cycle.

Again if your battery discharges from 100% to 25% and you plug in the phone and charge it from 25% to 100% then it will be 3/4 Charge Cycle.

This unique Charge Discharge cycle makes the Lithium-ion battery last longer than normal batteries.

If your smartphone battery doesn’t reach 0% then your battery won’t lose the charge-discharge cycle quickly. That is why all smartphone manufacturers advise you to never let your battery discharge to 0% before charging it again.

The best time to recharge your smartphone is before it discharges to 50% charge. If you can charge your phone before it discharges to 50% then you’ll save a lot of Charge-Discharge cycles and prolong the life of your Smartphone battery.

Does Charging Your Phone Overnight Ruin the Battery?

Charging your phone overnight does absolutely NO damage to the battery. Excessive charging has no effect on your battery.

I mentioned in the introduction that Lithium-Ion batteries are smarter than AA and other normal batteries. The reason for this is that Lithium-ion batteries have a unique mechanism by which it stops charging once the battery has been fully charged to 100%.

If you keep on charging the battery then there will be no effect on the battery because it stops the charging-discharging cycle.

If you leave your phone to charge overnight then there is no decrease in the number of charge-discharge cycles once it reaches 100%. Since there is no reduction in the charge-discharge cycle, therefore, there is no reduction in battery life or any battery damage.

This unique mechanism helps the Lithium-Ion battery to save charge and prolong the battery life.

But, there is one thing that can cause serious damage to the batteries and that is Extreme Temperature. Very High or Very Low temperatures can affect your battery capacity and battery life.

You should never charge your phone on a surface that can get too hot or too cold. It is highly advisable that you don’t charge your phone over a metallic surface, pillows, blankets, and other heat conducting surfaces.

The reason for this is that extreme temperature affects battery capacity and battery life.

In some cases like a faulty charger or a fault in the charging point may lead to leakage of charge even when it is plugged into charging.

Effect Of Temperature On Lithium-Ion Battery Performance

When the temperature is very low then internal resistance increases and your battery capacity will decrease. This means a full charge will only lead to a 50% battery charge and not 100%.

If the temperature is very high then the internal resistance decreases and your battery life will decrease. This means your battery cannot complete the minimum 300 charge-discharge cycles anymore.

What Is A Safe Operating Temperature For A lithium Ion Battery?

The safest operating temperature for a Lithium-Ion battery is around 26 – 27 degrees Celsius and around 78 – 81 degrees Fahrenheit. This temperature is called Normal Room Temperature.

Factors That Ruin Smartphone Battery Life

There are three main factors that ruin your battery life.

(a) Extremely hot and extremely cold temperatures while charging.

(b) Charging your phone after it gets discharged fully to 0%.

(c) Charging your phone on heat conducting surfaces.

How To Increase Smartphone Battery Life

You can increase the battery life of your smartphone by following these three practices.

(a) Don’t charge your phone on heat conducting materials like metal surfaces, blankets, pillows, etc.

(b) Never let your phone discharge to 0% before plugging it back again to charge. The best way is to plug it in before it reaches 50% battery life.

(c) Make sure that you don’t charge your phone at very low or very high temperatures. For North American and European countries, make sure you charge your phone at a temperature of around 26-27 degrees Celsius when it’s very cold outside.

These practices can reduce the rate at which battery life decreases. But remember every battery has a certain lifetime and you cannot increase your battery life beyond that.


Charging your phone overnight doesn’t damage the battery because Lithium-Ion phone batteries use a mechanism to stop charging when it reaches 100% charge.

Temperature can affect the longevity of your phone battery so make sure you don’t charge your phone on heat conducting materials and under very low or very high temperatures.

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