It’s frustrating when your phone starts getting hot and the battery drains faster than usual. A hot phone that’s losing power quickly can be inconvenient at best and dangerous at worst. But what causes this issue and what can you do about it?
What makes a phone hot?
There are several potential causes of a hot phone:
- Using resource-intensive apps and features like 3D gaming, video streaming, or video calls
- Poor signal reception forcing the phone to work harder
- Direct sunlight or hot environments
- Charging with fast chargers that generate more heat
- Too many background apps running
- Older phones with worn-out batteries
- Dust or debris blocking cooling vents
- Software issues or crashes
The most common reason tends to be resource-intensive use like gaming or streaming video. The processor ramps up power consumption to provide smooth performance, generating excess heat in the process. Poor signal and charging can also heat up the battery and circuits.
How phone components contribute to heat
Inside your phone, the main heat sources are the processor (CPU), graphics chip (GPU), display, battery, and cellular modem for managing mobile connections. Here’s how each component contributes to heating:
Processor (CPU)
The processor does the heavy computational lifting to run the phone’s apps and features. More intensive tasks make it work harder and hotter.
Graphics processor (GPU)
The GPU handles rendering all the visuals on your display. Graphics-intensive games and videos push it to its limits.
Display
High brightness levels on LED/OLED displays generate heat, especially with high-resolution screens.
Battery
Batteries produce some heat while charging and discharging to provide power to the phone.
Cellular modem
Poor reception forces the modem to keep searching for signal, wasting power and generating excess heat.
How software and apps affect phone temperature
The operating system and apps running on your phone also influence how hot it gets. Here are some software factors:
- Resource-intensive apps like 3D games use more processing power, resulting in more heat.
- Buggy apps that crash frequently make the processor and GPU work harder to recover, heating up the phone.
- Too many apps running simultaneously increase CPU workload and temperature.
- Large software updates use a lot of CPU resources during installation.
- Syncing large amounts of data from the cloud and transferring files can generate excess heat.
- Streaming high-resolution videos is graphics-intensive for the processor and display.
Closing background apps, avoiding resource-heavy use cases, and troubleshooting software issues can help minimize phone heating from the software side.
How heat impacts battery life
Excess heat can accelerate battery aging and degradation, reducing its overall lifespan. Here’s how heat damages smartphone batteries over time:
- Heat accelerates side reactions inside the battery, like electrolyte decomposition and metallic lithium plating.
- It strains the natural elasticity of components like the separator and electrolyte.
- High temperatures encourage faster development and growth of metallic lithium dendrites that can pierce the separator.
- Heat damages the solid electrolyte interphase (SEI) layer that regulates reactions.
These effects combine to form compounds that destabilize battery chemistry and reduce capacity. Exposure to sustained high temperatures can cause permanent loss of performance.
Heat’s impact on smartphone battery charge cycles
Heat also influences how quickly your battery runs through charge cycles. As a lithium-ion battery charges and discharges, it gradually loses capacity over hundreds of cycles. While phone batteries are designed for daily cycles, heat can accelerate cycle aging.
Charging at higher temperatures brings the battery to its upper voltage limit faster. Stopping the charge quickly prevents a full charge. Discharging also finishes sooner at hotter conditions. Repeated shallow cycling like this wears out the battery.
One study by researchers at the University of Michigan and Massachusetts Institute of Technology found that around 35°C, a phone battery can lose around 20% of its charge capacity after just 250 cycles. At cooler 25°C conditions, it required nearly 1,500 cycles to reach that same level of degradation.
Should you use the phone while charging in hot conditions?
It’s best to avoid using the phone intensively during charging at high temperatures. Charging alone already produces some heat, and heavy usage adds to it. The combination can accelerate battery aging over time compared to charging while idle.
Consider charging overnight while the phone is cool and unused, such as on a bedside table. Try not to cover the phone or charger to prevent any extra heat buildup.
How to keep your phone cool
Here are some tips to prevent your phone from overheating and preserve battery life:
- Close unused apps that run in the background
- Turn off Bluetooth, Wi-Fi, and location services when not needed
- Disable auto-syncing for cloud services temporarily
- Avoid prolonged direct sunlight exposure
- Don’t charge and use intensively at the same time
- Use phone cases with ventilation
- Keep the phone away from other hot objects and surfaces
- Avoid covering the phone with bedding or tight clothing when charging
- Disable CPU-intensive features like Always On Display
- Lower screen brightness
- Pause resource-heavy activities like gaming during charging
- Use phone cooling accessories
- Upgrade to a newer phone if battery performance is degraded
Monitoring your phone’s temperature and being mindful of conditions that cause excessive heat can go a long way towards maximizing battery lifespan.
Should you put your phone in the fridge to cool it down?
No, you should never put your phone in a refrigerator or freezer. The extreme cold can cause moisture in the air to condense and freeze on the phone’s internal components when you take it out. This water can damage electronic circuits and screens.
The ideal storage temperature for lithium-ion batteries is around 15°C. Storing at below 0°C strains the electrolyte and can cause permanent loss of battery capacity. The fridge is too cold for safe phone cooling.
When to be concerned about phone overheating
Occasional warmth under heavy usage is normal, but consistent overheating can threaten your phone’s health and safety. Here are some warning signs to watch out for:
- Phone feels hot to the touch even when idle
- Apps and features lag or crash frequently
- Battery charges very slowly
- Battery life has diminished significantly
- Phone shows warning message about temperature
- Display or casing warped/deformed from heat damage
- Burning smell coming from the phone
If you notice any of these issues, discontinue usage and have the phone checked by the manufacturer. Persistent overheating can permanently damage the battery or other components. Catching it early improves the chances of recovering performance.
When to replace the battery due to overheating issues
If your battery is old, it has lower heat tolerance and you should consider replacing it. Apple suggests replacement after approximately 500 complete charge cycles, when battery capacity falls under 80%. Android phones may need replacement around the 400 cycle mark.
Even before maximum cycles, a battery that consistently overheats or causes the phone to get hot suggests imminent failure. Have your phone checked as soon as possible if temperature issues develop.
How to maintain your smartphone battery
Proper care and handling gives your phone battery the best chance of avoiding overheating issues. Here are some battery care tips:
- Avoid exposing your phone to high temperatures like hot cars or direct sunlight.
- Don’t let the battery completely drain to 0% if possible.
- Charge the battery before it drops below 20% capacity.
- Use the original OEM charger and cable for optimal performance.
- Disable fast charging if you don’t need quick top-ups.
- Avoid using the phone while it’s charging at high temperatures.
- Don’t use third-party batteries of questionable quality.
- Charge the phone overnight while cool and unused.
- Consider charging to only 80% if leaving it plugged in for extended periods.
Moderating usage to avoid heat is also beneficial. Only use resource-intensive apps and features when necessary and close background processes.
Should you drain the battery completely before charging?
No, lithium-ion batteries used in phones today do not need to be completely drained and should not regularly drop below 20% charge. The natural voltage decline during discharge is enough for calibration.
In fact, fully draining the battery puts strain on it and can lead to premature failure. Regularly discharging below 20% can also wear out a battery faster. The safest approach is to recharge at moderate levels of 20-40%
When to replace your phone due to battery issues
If your battery is swelling, damaged, or no longer holds sufficient charge, it’s time to replace the phone. Here are some indicators of the end of a phone’s useful service life:
- Phone frequently gets hot even when not in use
- Battery lasts less than 2-3 hours per charge
- Charging the battery takes multiple hours
- Phone randomly shuts down despite showing charge
- Casing doesn’t close properly due to swollen battery
- Visible physical damage like cracks and punctures
Typically, phone batteries lose about 20% of original capacity per year. After 2-3 years, degraded performance becomes obvious. At that point, replacing the phone is usually a better investment than just replacing the battery.
Conclusion
A hot phone that loses battery quickly can stem from intensive usage, software issues, old batteries, or environmental factors. While occasional heating is normal, sustained high temperatures accelerate aging and shorten battery lifespan. Careful usage, controlled charging conditions, and monitoring your phone’s thermal behavior can maximize battery health. If degradation persists despite your best efforts, replacing the battery or phone may be necessary.
