In summer don’t use a smartphone as a dash cam or GPS


Why? In summer the inside temperature of a locked car can exceed 85°C when the outside temperature is only 35°. BTW humans begin to meltdown at a 41.5° core temperature and roast lamb is medium done at 65°.

In summer, temperature has a profound effect on the performance and longevity of a smartphone

The operating temperature of most smartphones is 0-35°. Why?

The melting point for the hot- melt adhesive is about 80° – the heat from a hairdryer. Hot melt adhesive holds the front glass and the battery in place. In summer the battery expands, pushing upwards, forcing the glass outwards destroying any semblance of water resistance.

A dedicated GPS or Dashcam does not use hot-melt adhesive.

The usual operating temperature of the smartphone battery is 40-50°. In summer it raches a lot higher

At higher temperatures, the battery needs to work harder to support the significant power draw of a GPS or dashcam. That extra work increases the heat factor inside the battery and can damage it. At above 85°, this can lead to thermal runaway, fire, and explosion.


A dedicated GPS or Dashcam uses a supercapacitor instead that is not subject to the battery heat. These also power ‘car park’ incidents that smartphones miss.

Liquid Crystal (LCD) Touch screens are heat intolerant in sumer at over 35°

LCD screens can permanently discolour, fog or get a rainbow effect. They can also warp and pop out of the frame.


A dedicated GPS or Dashcam uses an extended temperature range screen that will withstand 75° – close enough.

Smartphone – never intended to replace dash cam and a GPS

In all but the most powerful smartphones, the CPU/GPU is incapable of both running the phone as well as the GPS and refreshing the screen in real-time. This means lag and that single GPS antenna 10-metre accuracy can double making the device ineffective for both uses.

And unless you connect to a power source most 4000mAh batteries will empty in 2-3 hours.

Poor daylight screen readability

Unless you have a flagship AMOLED screen with very high brightness (at least 500 nits and almost infinite contrast) and low screen reflectivity, then the typical LCD smartphone is damned hard to see in daylight or direct sunlight. I have tried with everything from cheapies to $1000+, and all LCD screens suffer in daylight.

LCD screen versus OLED

A dedicated GPS or Dashcam uses a screen and themes that have high viz and lower reflectivity.

Limited driver aid or navigation smarts

Smartphone navigation software does not have the level of driver aid, landmark navigation, complex intersection pictures, and so many more things we take for granted to get from A to B.

And free map apps all suffer from advertising and points of interest, taking up valuable screen real estate.

Speed camera location is nowhere near what a dedicated GPS or Dashcam provides and you don’t get advertising garbage to confuse you.

Navman nav screen

Inaccurate Speed and GPS coordinates

On a recent 1000km test, the smartphone regularly reported between 97 to 120kph when the digital speedo/cruise control was at 100kph. Both the in-car unit and the Navman MiCam Explore 7 (review here 4.9/5) were spot on all the time.

A dedicated GPS or Dashcam uses a more sophisticated multi-satellite fix and has stronger GPS antenna. Most smartphones use Assisted-GPS to gain a satellite fix and often lose that fix at speed.


Poor cameras not suitable for the task

The typical smartphone camera has a 60-70° Field-of-View. A dashcam has around 130° horizontal and 70° vertical to get the whole road and side streets.

Said smartphone might have plastic lenses that will warp in the heat. The green tinge appeared after five hours of use and never left. Dashcams use heat resistant glass lenses.

Typical smartphones have auto-focus, 1-1.6um pixels and f/2.0 or smaller apertures, so they are fine in good light and abysmal in low light. Autofocus can lead to severe bokeh effects that may obscure vital details.

Most dashcams use 2.4um large pixels, fixed focus (up to three car lengths) and the better ones use Sony Starvis low light BSI sensors. When you need to read a number plate, only a dashcam can.


A typical smartphone can only record for 30 minutes, creating a single 1080p file of approx: 3,000 MB or 32GB (approx.). If you have more storage you can start recording again for another 30 minutes or until the storage is full. At this time, you need to either back up the file to external storage (can take 100 minutes over USB 2.0) or delete it to make more room.

A typical dashcam creates a series of 100Mb files each minute it continuously films. Once the MicroSD card is full (many support 128GB or more) it records over it, apart from autosaved ‘event images’. And you don’t have to restart/launch the app every 30 minutes.

Inaccurate maps

While you think Google Maps and Apple Maps are up to date, the fact is that most are out-of-date unless you manually update them regularly.

In our 1000km test, the smartphone with Google Maps (10.56. 1 latest) was unable to identify huge areas of the updated Pacific Motorway from Coffs harbour to Coolangatta as well as new tunnels or road adjustments. The in-car and Navman had November 2020 maps.

Note that while law enforcement accepts footage from dedicated dash cams as evidence, smartphone footage used as a dashcam is inadmissible under the chain of evidence provisions.

A special note on free GPS and dashcam apps

Remember the Police song

Every breath you take
Every move you make
Every bond you break
Every step you take
I’ll be watching you

Every single day
Every word you say
Every game you play
Every night you stay
I’ll be watching you

You have no privacy at all when using a smartphone as a GPS or a Dashcam. All movements are tracked, and it can use mobile data as well.

Free dashcam apps also store metadata in their cloud and monetise that via advertisements or selling your data to advertisers.

GadgetGuy’s take – In summer don’t use a smartphone as a dashcam or GPS

Dedicated in-car GPS and dashcams have the power for real-time processing, daylight readable screens, no advertising clutter and won’t lose your licence if you touch them!

Our test was simple – the smartphone failed in almost every way from heat issues to inaccurate maps and directions.

If you must use a smartphone for a job it was never designed for then do not leave it in the car, do use a cradle and connect it to a power source.