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  • Writer's pictureSolar On EV

My "Hot Car" - how "Hot" is it?

Updated: Nov 16, 2021

People love to drive a “Hot Car”, Lamborghini, Porsche, Audi R8, etc.

I’m sorry, this is not the topic. I’m talking about an overheated “Hot Car”.

I live in Sydney, Australia. The weather is good, and I usually have my car parked on the street during the day. Summer is not hot, but your vehicle becomes an oven if you leave your vehicle under the sun for long enough. It was killing me because I was in/out and drove around under the sun, usually for a short distance.

A sedan is melting on a road like ice cream
Image shown an illustration of an animated melting car

An Oven Under The Sun

Have you ever left something in your car, say an empty water bottle, when you came back, it shrank?

Have you ever tried to cook a boiled egg (with no water) in your car by just leaving it above the dashboard under the sun? It’s like magic; it works.

To make it worst, I even tried making a “Sunnyside Up” on foil paper. Egg white and egg yok start to cook at a different temperature, between 70C - 80C. It took a bit more time, but cooked fully. The outdoor reported temperature on that day was only 29.8C max in Sydney (only 29C maximum from my thermometer).

Since then, I started a project to track inside my car’s temperature. The following shows temperature recorded for Jan 2021 on chart:

How "Hot" Inside Your Car

It is my other car and not used often, parked on the driveway. It’s perfect for measuring the car’s compartment temperature changes 24 x 7. Although there may be days that the car was driven, and the maximum temperature recorded may have been affected. Most of the readings were recorded for full-day parking.

On the chart above, there are three different readings,

  1. (the white) the max temperature reported from BOM (Bureau of Meteorology, Sydney station# 066124);

  2. (the blue) the maximum temperature recorded from my car’s compartment;

  3. (the yellow) the maximum temperature recorded from my car’s dashboard area;

The temperatures were recorded through 2 separate temperature logging devices in 5-minute recording intervals, connected via Bluetooth to my phone, and downloaded in excel format.

The 1st bar shown on the left is the month’s highest temperature of the three readings. It may not be from the same day, but it usually does. This month’s highest temperature for all three readings was from the 26th of Jan, 2021, with dashboard and compartment temperature at 95.6C and 78.32C, respectively. The BOM record on the day is also the highest of the month at 40C.

It is a horrible result. No wonder I can cook eggs in my car.

Doubling The Temperature

However, if you check carefully on the rest of the figures, I think the 26th of Jan hasn’t reached its full potential. As a comparison below,

Table shows a comparison of the rate of increase of car's temperature from various outdoor temperature
Sample of temperature increase (in Celsius) and the rate of increase in % (Green is the highest value of each column)

Although 26th Jan has the highest BOM reported temperature of the month, the max compartment temperature reached only beaten 22nd Jan marginally by 0.17C, with a 4.2C of the outdoor temperature difference (40C - 35.8C) reported. In contrast, the highest percentage increase was 257% on the 11th of Jan compared to only 196% on the 26th of Jan.

On the 26th of Jan, the Dashboard temperature increased from 40C to 95.6C by only 239% compared to 305% on the 11th of Jan, with an actual increase of 17.39C compared to 18.56C on the 5th of Jan.

The day was hot, with some clouds. I wonder it affects its performance. Does anyone think that it might be enough to melt a car if its temperature goes higher?

Dangerous Temperature Keeps Getting Higher

There were incidents about cars melting around the world; only a few were genuine. Most reported damages to the dashboard or the plastics outside.

A cartoon picture of a sun is too hot and melting everything, including the sun herself.
Pic of the sun is melting everything

Remember the extreme heat waves around western North America in Jun/Jul 2021. The temperature went to the roof close to 50C in many places. Inside the car compartment, the temperature is likely above 100C, and you could probably cook an egg in 10 mins. I hope it doesn’t boil water but likely steams.

Think about how much damage it is inside your car? How much damage to a human who tries to get in? Toddlers and the elderly jeopardize around the world because of overheated vehicles.

Save Our Climate, Save Our Future Generations

Global warming, Climate change, extreme weather are real, and they are happening. Canada has recorded the highest temperature ever recorded at 49.6C during that heat wave. China just had a horrific rainfall ever recorded of 617.1mm under 72 hours at Zhengzhou, Henan, flooded and killed many people. One of the others may come around and hit anyone someday.

Global warming is here, get up and do our parts.

My experiment is still going. Contact me if anyone is interested to learn a bit more.



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