Can overheating damage your phone battery?

Quick Answers

Overheating can definitely damage phone batteries. High temperatures put strain on the battery components and accelerate capacity loss. The extent of damage depends on how hot the phone gets and for how long. Sustained overheating above 45°C can permanently reduce battery life. Occasional high temps are less harmful but still wear the battery faster over time. Keeping phones cool protects battery health.

What causes phones to overheat?

There are several main causes of overheating in phones:

Intensive app use

Apps that utilize a lot of processing power like 3D games can make phone components heat up quickly. The CPU and GPU work harder, generating more heat.

Bright display settings

Having your screen brightness set high for extended periods adds heat to the phone. The display is one of the biggest battery drains.

Direct sunlight

Leaving your phone in direct sunlight is a surefire way to overheat it. The infrared and visible light radiation from the sun warms up the phone.


Charging your phone when its battery is already hot can drive temperatures higher. Fast charging also produces excess warmth.

Poor airflow

Blocking the phone’s ventilation or using it in hot confined spaces prevents heat from dissipating, leading to overheating.

Faulty battery

Defective lithium-ion batteries can overheat due to internal shorts or reactions. This is rare but does happen.

Hardware problems

Phone hardware issues like a damaged processor or clogged cooling fans can interfere with heat dissipation and cause overheating.

How hot is too hot for a smartphone battery?

Most lithium-ion batteries used in smartphones today have a safe operating temperature range of 32°F to 113°F (0°C to 45°C). Temperatures beyond that threshold can start degrading components:

120°F – 140°F (49°C – 60°C)

At these temperatures, the electrolyte solution in the battery begins to break down through uncontrolled chemical reactions. Gas builds up inside the battery which can lead to swelling. Battery capacity starts decreasing faster.

>140°F (>60°C)

Above 140°F, the binder materials and separators within the battery can melt or warp. This can create internal shorts, leading to thermal runaway where the battery overheats continuously. Permanent damage is very likely at these temperatures.

167°F (75°C)

This is around the typical thermal runaway temperature for lithium-ion batteries. The battery will vent gas, smoke, or even catch fire at this temperature. The damage is irreversible.

So in general, sustained heating above 45°C (113°F) accelerates battery degradation, while temperatures exceeding 60°C (140°F) can be dangerous and destroy the battery.

How does overheating actually damage batteries?

There are a few key ways heat impacts lithium-ion battery components and performance:

Accelerates side reactions

The electrolyte, electrodes, and other materials inside the battery undergo side reactions that degrade them over time. Heat speeds up these unwanted reactions, wasting lithium ions.

Reduces electrolyte life

The electrolyte allows lithium ions to flow between the anode and cathode. But high heat breaks down the electrolyte more quickly.

Warps physical structure

Overheating can melt separators causing internal shorts. It also expands battery materials, weakening connections. This gradually reduces capacity.

Damages protective coatings

Extreme heat degrades the protective coatings on anode and cathode materials. This allows further undesirable reactions that ruin the materials.

Forms more solid deposits

High temperatures encourage the growth of solid deposits like lithium plating that reduce electrolyte mobility and battery performance.

So in summary, overheating accelerates aging effects like oxidation, material breakdown, and physical damage that permanently lower battery life and capacity.

Can overheating damage happen gradually?

Yes, battery damage due to overheating can definitely occur gradually over time. The higher temperatures don’t have to be sudden spikes. Sustained mild overheating can still degrade batteries.

Here are some examples of gradual overheating damage:

– Using phone outside in hot weather everyday

– Regularly fast charging to high temperatures

– Playing demanding 3D games for hours daily

– Leaving phone in hot car day after day

– Talking on phone for long periods against your face

The repeated exposure to temperatures above 45°C wears the battery materials down over time. Capacity begins fading faster than normal.

While high temperatures during charging or discharging are the main culprit, even idle overheating impacts longevity. Keeping a phone cool whenever possible is key to maximizing battery lifespan.

Does overheating during charging harm the battery?

Yes, overheating while charging can absolutely damage phone batteries. In fact, heat during charging is more detrimental than heat during normal discharge.

Charging creates heat due to the current flowing into the battery. Fast charging heats up batteries even more.

If the battery temperature rises above 45°C during charging, permanent damage occurs:

– The high-voltage charger amplifies unwanted chemical reactions.

– Electrolyte wears out faster.

– Deposits accumulate more rapidly on electrodes.

– Materials like separators are more vulnerable to warping.

So excessive heating while charging accelerates capacity loss and shortens battery life. It’s best to avoid charging when your phone is already hot, like in direct sunlight.

Ideally, lithium-ion batteries should be charged below 40°C to minimize damage. Never charge at temperatures exceeding 60°C as it can be unsafe.

What are the permanent effects of overheating?

Here are some of the permanent effects overheating can have on smartphone batteries:

Lower maximum capacity

Sustained heat exposure reduces the battery’s ability to hold a full charge. For example, a battery might only charge up to 2700mAh instead of its original 3000mAh.

Faster capacity degradation

The battery will experience greater capacity loss during normal charge cycles compared to cooler operation. Lifespan is shortened.

Loss of charging ability

Extreme overheating can completely destroy internal structures required for charging and voltage regulation. Total failure results.

Internal shorts

Insulating materials and separators can be damaged by heat, causing internal shorts between electrodes. This can lead to thermal runaway.

Swelling or deformation

Overheating often produces gas which expands the battery casing. High heat can also melt internal structures.

So in summary, overheating permanently accelerates battery degradation and shortens overall lifespan. The effects worsen at higher temperatures.

Does overheating reduce battery lifespan?

Absolutely. Elevated temperatures markedly reduce the overall lifespan of smartphone batteries. Overheating accelerates all the normal degradation processes.

Research on lithium-ion batteries shows that:

– Capacity loss doubles for every 10°C (18°F) increase above room temperature.

– Operating above 45°C (113°F) cuts the cycle life to 50% after just 150 cycles.

– At extreme temperatures above 60°C (140°F), battery lifespan is reduced by 95% or more.

So even occasional overheating takes a toll on battery longevity over time. Sustained high heat severely shortens the usable life of the battery.

Keeping your phone cool as much as possible prolongs the battery lifespan. Letting it regularly overheat in hot cars, direct sun, etc. will wear the battery out much faster.

Can overheating damage be reversed?

Unfortunately overheating damage to lithium-ion batteries cannot be reversed or repaired. The physical and chemical changes are permanent.

For example, overheating:

– Can’t undo degraded electrode coatings or melted separators.

– Doesn’t replenish depleted electrolyte.

– Can’t eliminate plating deposits or swollen casings.

– Doesn’t restore lost lithium ions.

The cumulative effects of heat remain even if the battery is cooled down. Capacity and lifespan are reduced based on total exposure.

However, stopping further overheating prevents additional damage. While you can’t undo previous heat effects, keeping the phone cool going forward will help extend the remaining battery life.

How can I prevent overheating damage?

Here are some tips to avoid overheating your phone battery:

Don’t leave in hot places

Avoid leaving your phone in cars, direct sunlight or other hot areas. Even idle overheating accelerates battery degradation.

Limit intensive app use

Don’t play graphically demanding games or run other stressful apps for too long. Give your phone breaks to cool off.

Use lower brightness

Keep screen brightness lower when possible. High settings heat up the display and battery.

Remove cases periodically

Thick cases can block heat dissipation. Take them off periodically to let your phone cool better.

Avoid wireless charging

Wired charging generates less heat. Wireless charging heats up phones more.

Charge in cool conditions

Don’t charge your phone in hot ambient environments. Heat during charging does the most damage.

Replace if damaged

Get your battery replaced if it shows signs of overheating damage like swelling or reduced capacity.

Being mindful of phone temperature and avoiding sustained heat are the best ways to maximize your battery lifespan.

How to tell if your battery was damaged by overheating?

Here are signs that indicate your smartphone battery may have been damaged by excessive heat:

– Reduced running time between charges

– Inability to hold a full charge

– Swelling or deformation of the phone casing

– Significant capacity loss according to a battery app

– Phone shutting down unexpectedly at higher battery levels

– Feeling uncomfortable warmth during use and charging

– Slow charging or failure to charge in some conditions

– Noticeable lag or shutdown when running intensive apps

– Battery no longer lasting as long as when brand new

Minor heat damage shows up as slightly accelerated capacity loss over time. More severe overheating can permanently slash battery lifespan and even prevent charging entirely.

Should I replace my battery if damaged by heat?

If your smartphone battery shows signs of reduced capacity or swelling from overheating damage, replacement is a good idea to restore optimal performance.

A brand new battery will give you back the running time and longevity you expect. Heat damage is irreversible so a replacement is the only fix.

Before replacing due to overheating issues, try these steps:

– Update to the latest OS version

– Reset app preferences

– Check for abnormal app battery drain

– Test battery health with an app

– Contact manufacturer support

If it still seems heat caused permanent degradation, then replacement is likely your best option. Consider an OEM battery for reliable quality and safety.


In summary, overheating absolutely can damage lithium-ion batteries in smartphones and reduce their lifespan. Sustained high temperatures above 45°C degrade battery components through accelerated chemical reactions and physical damage.

Occasional heat is less detrimental but can still noticeably shorten battery life over time. Preventing overheating as much as possible will help maximize your phone’s battery lifespan. Be mindful of heat during intensive use and charging. Replace swollen or degraded batteries promptly to restore normal runtime.