A chamber that turns up the heat on electric cars
The carmaker ŠKODA uses this special solar chamber to simulate, over a 25-day period, what happens when an electric car spends four years in the conditions of a Central European climate. The test reveals how a car’s parts and materials behave during this time and whether there is any degradation, including visual degradation.
“In Volkswagen Group it’s only Audi and ŠKODA who have an electric car test chamber. Audi’s solar chamber is in China, and ours is a bit more modern and has more safety systems,” boasts Petr Sobotka, head of Material Technology and Special Measurements, about his new workplace.
The solar simulation chamber will be used primarily for electric vehicles.
The chamber, which took a little over a year to build, is a carefully isolated room fitted with a set of 28 light emitters with an output of 2.5 or 4 kW. These are metal-halide light emitters whose light best approximates the spectrum of real sunlight. The emitters only have a lifespan lasting three tests or so, then they all have to be replaced.
Thermal cameras check the differences in temperature inside the car during the test.
Next door is a machine room with a special air-conditioning apparatus and a “brain” to control the power supply. The chamber makes it possible to model various temperature, humidity and sunlight conditions. “We can simulate a desert climate, for example, or a freezing night in the mountains. During a test, we switch between a hot Arizona day, with an air temperature of 42°C in the shade and a sunlight intensity of up to 1000 W/m2, a Florida-style climate with extreme humidity, and a cold Alpine night when the mercury drops to -10°C,” says Dalibor Kopáč, test coordinator, describing what a test involves.
The chamber is next to the control room with a special ventilation system and the “brain” of power management.
The entire process is controlled from the control room, which is separated from the chamber by a thick wall. Personnel will soon also be able to supervise tests using their mobile phones.
Given the extreme conditions that prevail during tests (some parts of the car can heat up to a temperature of 110°C), safety must not be taken lightly. The room is full of sensors that monitor temperature. Thermo-cameras outside the chamber monitor cars that technicians are preparing for testing or have just completed a test. The chamber itself is equipped with a safety system that stops a test if there is any hint of a problem.
How the test takes place
The first fifteen days of the test simulate the hot, dry climate of the Arizona desert. Every 24 hours there are two one-day cycles when the car exposed to intensive sunlight of up to 1000 W/m2, an ambient temperature of 42°C and humidity below 30 per cent, and two night cycles with a temperature of 10°C. At the end of every day there is a one-hour servicing period at a temperature of 23°C, when technicians can enter the chamber to check the vehicle’s condition and change a faulty sensor, for example. The last ten days of the test simulate a humid Florida-style climate. During the daytime cycle the temperature is cranked back up to 42°C, but this time the relative humidity climbs above 60 per cent. From this temperature the chamber is cooled to the conditions of an Alpine night at minus 10°C.
Checking the car after the test.