How hot does a parked car get?
RACQ testing found the inside of a typical car parked outside can rise by 10 degrees in just 10 minutes (a February test, in a dark car), and warns it can skyrocket even in the shade or with a window open a little. The Queensland Family and Child Commission says about three-quarters of the rise happens in the first five minutes. An older RACQ survey, quoted by NSW Health, found a parked car can reach 70 °C inside on a typical 30 °C summer day.
So it's the quick stops that catch phones out: the shops at Taigum Square or Chermside, school pick-up with the engine off, a swim at Sandgate.
What do Apple and Samsung say about heat?
Both give the same range for using a phone: 0 °C to 35 °C.
- Apple says to store an iPhone between −20 °C and 45 °C, and warns that parked cars can go past that. Using it in very hot conditions can permanently shorten battery life. Apple also says to avoid dramatic changes in temperature or humidity.
- Samsung lists leaving a phone in a parked car on a hot day, and continual use in direct sunlight, among the causes of a Galaxy heating up.
What happens when it gets too hot?
Apple says a hot iPhone may slow or stop charging (wireless charging too), dim or black out the screen, weaken its mobile signal and switch off the camera flash for a while. You may see "Temperature: iPhone needs to cool down", though it may still be able to make emergency calls. Samsung says a hot Galaxy may close apps, stop charging, dim the screen or turn off.
Does heat damage the battery for good?
It can. Apple says temperatures above 35 °C can permanently damage a battery's capacity, so it won't run the phone as long on a charge, and that charging in high temperatures can damage it further. Samsung says use or charging in extreme temperatures may speed up battery deterioration.
It usually shows up as a battery that no longer lasts the day. Here's how to check iPhone Battery Health.
Why does my phone overheat on the dash when I'm using maps?
Because it's getting heat from three places at once: the sun through the windscreen, the charger, and navigation, which keeps the GPS, mobile data and screen busy the whole trip. Apple names this exact situation: navigation in a car in direct sunlight. Think of the run up the Bruce to the Sunshine Coast, afternoon sun on the glass.
Once the phone is too hot, charging slows or stops, which is why the battery can drop while it's plugged in. An iPhone may also hold charging at 80 percent when its battery is too warm.
If an iPhone turns its screen off while you're navigating, Apple says the spoken directions keep going, and the screen lights up again as you approach a turn.
Is a vent cradle cooler than a windscreen one?
In summer, usually:
| Cradle | In summer | Keep in mind |
|---|---|---|
| On the windscreen or dash top | The phone sits right behind the glass, often in full sun | Place it so it doesn't block your view of the road |
| On an air vent | Lower down, often out of direct sun, with the air con blowing across the back | With the heater on in winter, it warms the phone instead |
Either way, keep it clear of the airbags (your car's manual shows where they are).
What do Queensland's road rules say?
- You can't hold a phone or rest it on your body, including your lap, while driving, even at traffic lights.
- Open and P2 licence holders can use a phone hands-free, for example in a cradle attached to the car, to follow a map or take a call. It mustn't block your view of the road, and you must keep proper control of the car.
- Learner and P1 licence holders under 25 can't use any function of a phone while driving, even hands-free or Bluetooth.
Where is it safe to leave a phone in summer?
| Where | OK? | Why |
|---|---|---|
| With you, in a pocket or bag | Yes, the best place | You're cooler than a parked car |
| On the dashboard, parked | No | Full sun through the windscreen |
| On a seat, parked | No | The whole cabin heats fast |
| Parked in the shade, window down a little | No | RACQ says it still heats fast |
| Glovebox or console, quick stop | Better than the dash | Out of the sun, but still in a hot car |
| In the cradle, driving, out of the sun, air con on | Yes | Cooler air and no direct sun |
| In the cradle in full sun, charging and navigating | Watch it | The mix Apple says heats phones up |
It says it's too hot. What should I do?
- If you're driving, leave it in the cradle and deal with it once you've safely stopped.
- Unplug it, or take it off the wireless charger.
- Move it somewhere cooler, out of direct sun.
- Turn it off if you can, or close your apps.
- Let it cool by itself, then wait a few minutes before using it.
- Charge it again once it feels normal.
What shouldn't I do?
- Don't put it in the fridge, the freezer or the esky. A sudden chill is the dramatic change Apple warns against, and Samsung says not to keep a phone somewhere very cold.
- Don't keep charging it, or playing games or video, while it's hot.
Sources
- RACQ: RACQ's urgent safety warning as heatwave grips Qld
- Queensland Family and Child Commission: Protecting children from the dangers of heat in vehicles
- Central Coast Local Health District (NSW Health): Kids in cars (PDF)
- Apple Support: If your iPhone or iPad gets too hot or too cold
- Apple Support: Important handling information for iPhone
- Apple Support: Important safety information for iPhone
- Apple: Batteries: Maximizing Performance
- Apple Support: Charge and maintain your iPhone battery
- Samsung: Keep your Galaxy device at its normal operating temperature
- Samsung: Why is my Samsung phone overheating or getting hot
- Samsung: Samsung Mobile Device heats up while charging the battery
- Samsung: Galaxy Battery: Care and Maintenance
- Queensland Government: Driving and mobile phones
- Department of Transport and Main Roads: News and media frequently asked questions
Related repairs at Taigum Square