Why Your Phone Gets Hot While Charging and How to Fix It
2026-10-14 · Marion Phone Repair
Your phone gets noticeably warm or hot while charging. Some warmth during charging is completely normal — the battery generates heat as it accepts electrical current, and the charging circuitry itself produces heat during voltage conversion. But there is a difference between warm and dangerously hot. Here is how to tell the difference and what to do about it.
When heat during charging is normal
Every phone gets warm while charging. The amount of heat depends on the charging speed and what you are doing with the phone during charging:
Fast charging generates more heat: A phone charging at 25W or higher will feel warmer than one charging at 5W because more electrical current is flowing into the battery faster. This is expected behavior and the phone's thermal management system is designed to handle it
Using the phone while fast charging: The CPU generates heat from whatever you are running (gaming, video, navigation) while the battery simultaneously generates heat from fast charging. The combined heat can make the phone feel quite warm. Most phones will automatically reduce charging speed when temperatures get too high — this is a safety feature, not a malfunction
Wireless charging: Wireless charging is less efficient than wired charging. The energy lost during wireless power transfer becomes heat, so phones typically run warmer on a wireless charger than when plugged in with a cable
Normal charging warmth means the back of the phone feels warm to the touch but not uncomfortable to hold. You should be able to keep your hand on the back of the phone without pulling away. The phone is operating within its designed thermal limits.
When heat during charging is a problem
Excessive heat during charging is a concern if:
The phone is too hot to hold comfortably against your skin
The phone displays a temperature warning and stops charging (both iPhone and Android will do this when internal temperatures exceed safe limits)
The heat is concentrated in one spot rather than spread evenly across the back
The phone gets hot while charging even when you are not using it and no apps are running
The phone is hotter than it used to be under the same charging conditions
Common causes of excessive charging heat
Cheap or damaged charging cable or adapter
Low-quality charging cables and adapters that do not meet proper electrical specifications can cause excess heat in the charging port, the cable connector, or the adapter itself. Signs of a cable or adapter problem:
The cable connector or the area around the phone's charging port gets unusually hot (hotter than the back of the phone)
The cable is frayed, bent at the connector, or has visible damage
The adapter feels excessively hot to the touch
Use the charging cable and adapter that came with the phone, or a cable and adapter from a reputable brand that is rated for your phone's charging specifications. Cheap cables from unknown brands may not have proper voltage regulation or shielding.
Background apps consuming resources
Apps running in the background consume CPU power, which generates heat that adds to the heat from charging. Common offenders:
Navigation apps running with the screen off
Cloud backup or photo sync happening in the background
Social media apps refreshing content
Stuck processes or apps that have crashed but still consume CPU
Before plugging in to charge, close apps you are not using. On Android, check Settings, Battery to see which apps have used the most power recently. On iPhone, check Settings, Battery for the same information.
Phone case trapping heat
Phone cases, especially thick rugged cases and cases made of insulating materials like silicone, trap heat against the phone. The phone's thermal management relies on dissipating heat through the back panel, and a thick case acts as insulation. If your phone consistently overheats during charging, remove the case while charging and see if the problem improves. This is especially important with wireless charging, which already generates more heat than wired.
Charging in a hot environment
Ambient temperature matters. Charging your phone in direct sunlight, on a car dashboard, next to a heat source, or in a room with no air conditioning on a hot day means the phone starts from a higher baseline temperature and has less ability to dissipate the heat generated by charging. Move the phone to a cooler location during charging.
Degraded battery
As lithium-ion batteries age, their internal resistance increases. Higher internal resistance means more energy is converted to heat during charging. If your phone is 2 to 3 years old and gets noticeably hotter during charging than it did when new (under the same conditions), the battery may be significantly degraded.
iPhone: Check Settings, Battery, Battery Health and Charging. If Maximum Capacity is below 80 percent, the battery is degraded and Apple recommends replacement
Android: Check your manufacturer's battery health tool (Samsung: Settings, Battery and Device Care, Battery) or use a third-party app like AccuBattery to estimate battery health
How to reduce heat during charging
Do not use the phone while fast charging: Let it charge undisturbed. The battery heats up less when the CPU is idle
Remove the case: Especially for wireless charging or fast charging sessions
Charge in a cool, ventilated area: Not in direct sunlight, not under a pillow, not inside a closed bag
Use the original charger or a reputable brand: Avoid cheap cables and adapters from unknown manufacturers
Reduce charging speed if available: Some phones let you disable fast charging in Settings, Battery. Charging at standard speed generates significantly less heat than fast charging
Close background apps before charging: Especially resource-intensive apps like games, navigation, and video streaming
Charge before the battery is critically low: Charging from 5 percent generates more heat than charging from 30 percent because the initial charging phase pushes more current into the battery
When overheating during charging is dangerous
Lithium-ion batteries can become dangerous if they overheat severely. Stop charging and seek service if:
The phone or battery is swelling (the screen or back panel is pushing apart)
You smell a chemical or burning odor from the phone
The phone is too hot to touch
The charging cable or port is discolored, melted, or showing burn marks
A swollen battery is a fire risk. Do not continue using or charging the phone — power it off and bring it in for battery replacement.
Charging heat help in Marion
If your phone is overheating during charging and the steps above have not resolved it, Marion Phone Repair can test the charging system, check battery health, and determine whether the issue is the charger, the battery, or another component.