Wireless charging gets hot because transferring electricity through magnetic induction is less efficient than using a cable. Some input energy becomes heat in the charging pad, phone's receiver coil, charging circuitry and battery.
The system uses 2 coils. Heat can increase when the coils are misaligned, a case adds distance, metal sits between the devices or airflow is blocked.
Wireless Charging Heat at a Glance
| What you notice | Likely explanation | What to do |
|---|---|---|
| Slightly warm phone or charger | Normal energy-transfer losses | Keep both devices uncovered and ventilated |
| Very warm phone when it is off-centre | Poor coil alignment reduces efficiency | Centre the phone on the charging pad |
| Heat with a thick, magnetic or metal case | Extra distance or metal interferes with the magnetic field | Remove the case while charging |
| Heat around coins, keys or cards | Metal can develop eddy currents and heat up | Remove the object immediately |
| Charging slows or pauses | Thermal protection has activated | Let the phone and charger cool |
| Hot enough to be uncomfortable | Possible accessory, placement or hardware problem | Stop charging and inspect or replace the charger |
How Wireless Charging Creates Heat
A wireless charger contains a transmitter coil. Your phone contains a matching receiver coil. The charger sends alternating current through its coil, which creates a changing magnetic field. The phone's receiver coil captures that field and converts it into electrical power for the battery.
Heat can develop at several points in that process:
- The charger converts power from the wall adapter into high-frequency electrical current.
- Electrical resistance causes some energy loss in the transmitter coil.
- Power crosses a small air gap instead of moving through a direct electrical connection.
- The receiver coil converts the transferred energy into usable electricity.
- The phone's charging circuitry regulates that power for the battery.
Wireless charging has more conversion stages than wired charging. Apple warns that it may use more power than wired charging, while Google describes heat as a natural result of wireless power transfer.
Why Poor Alignment Makes Wireless Charging Hotter
The transmitter and receiver coils transfer power most efficiently when they are close together and directly aligned. Misalignment, a larger gap or mismatched coil sizes reduce the amount of magnetic energy that reaches the phone. The remaining energy becomes additional heat.
A phone may heat up when:
- It slides away from the centre of a flat charging pad.
- The camera bump prevents it from sitting flat.
- A thick case increases the distance between the coils.
- The phone rests at an angle.
- The charger uses a small or poorly designed coil.
Qi2 magnetic chargers help keep the phone and charger in the correct position. The Wireless Power Consortium says accurate alignment improves efficiency and reduces energy lost as heat.
Can a Phone Case Cause Wireless Charging Heat?
Yes. A case can raise the phone's temperature in two main ways.
A thick case increases the distance between the charging coils. A case with magnets, metal plates, ring holders or other magnetic accessories can also interfere with the charging field.
Google advises removing thick or metallic cases if wireless charging is slow or unstable. Apple advises removing metallic cases and keeping metal objects away from the charger.
A thin, non-metallic case usually causes fewer problems. For magnetic Qi2 charging, a Qi2-compatible case is the safer choice.
Why Metal Objects Get Dangerously Hot
Coins, keys, jewellery, paper clips and some cards can heat up when they sit between a wireless charger and a phone. The charger's alternating magnetic field can create eddy currents in conductive materials. Those currents turn electrical energy into heat inside the metal.
Do not place these items on a charging pad:
- Coins and keys
- Metal plates or magnetic ring attachments
- Bank cards and security badges
- Jewellery
- Metal cases or inserts
- Loose batteries or other conductive objects
Qi-certified chargers include foreign-object detection and thermal controls, but remove metal objects rather than relying on the charger to detect them.
Why Wireless Charging Gets Hotter in Some Situations
Wireless charging is more likely to feel hot when:
- The battery is very low and the phone is accepting power quickly.
- Fast wireless charging is enabled.
- The phone is being used for gaming, video recording, navigation or a mobile hotspot.
- The phone is in direct sunlight or a hot car.
- Bedding, clothing or another object blocks airflow around the charger.
- Poor cellular reception makes the phone use more power.
- The power adapter is incompatible or low quality.
Google notes that a Pixel phone or Pixel Stand may feel especially warm when charging from a very low battery. Google also recommends keeping the phone cool, removing unsuitable cases and leaving the charger uncovered.
Is It Normal for Wireless Charging to Feel Warm?
Slight warmth is normal. Heat that makes the phone or charger uncomfortable to hold needs attention.
Apple and Google include temperature controls in their phones. If the device gets too warm, charging can slow down, pause or stop until the temperature returns to a safer level.
Stop charging and check the setup if the phone or charger:
- Becomes too hot to hold comfortably
- Repeatedly pauses charging
- Charges unusually slowly
- Produces a burning smell
- Shows signs of damage or discolouration
- Gets hot even when it is correctly aligned and used without a case
How to Make Wireless Charging Cooler
Centre the phone over the charging coil. Use a magnetic Qi2 charger if your phone supports it.
Remove thick, metallic or incompatible cases. Also remove magnetic rings, card holders and metal plates.
Keep the charging surface clear. Do not place coins, keys, cards or jewellery between the phone and charger.
Use a Qi Certified or Qi2 Certified charger. Certification indicates that the product has been tested against relevant power, thermal and foreign-object requirements.
Use the correct power adapter. An unsuitable adapter can cause charging problems and excess heat.
Avoid heavy phone use while charging. Gaming, video recording and navigation add heat from the processor and display.
Improve ventilation. Keep the charger on a hard, uncovered surface, not under a pillow, blanket or item of clothing.
Let the charger cool before trying again. If it still becomes excessively hot, stop using it and replace the charger or contact the manufacturer. Google advises discontinuing use if a PixelSnap charger feels unsafe.
When to Stop Using a Wireless Charger
If centring the phone, removing the case, clearing the charging surface and improving airflow do not reduce the heat, stop using the charger. Replace it or contact the manufacturer before charging again.