By Tabea Schlürscheid and Jean-Paul Ravier
Tabea Schlurscheid and Tran Quoc Khanh from Darmstadt University, and Alexander Buck and Stefan Weber from BMW, have jointly published an article in Applied Science. In it, they examine the temperatures in headlamps in electric and combustion-engine vehicles. The 14-page paper, entitled Temperature Behavior in Headlights: A Comparative Analysis Between Battery Electric Vehicles and Internal Combustion Engine Vehicles, is freely downloadable. Tabea will be on stage at the DVN Munich event to present the results of the study.
A key anchor for the research was the need to ensure that all light functions meet applicable regulatory and technical standards in all driving situations. Applicable standards include AEC-Q102 and ISO 16750 that dictate the thermal requirements and lifetime testing procedures for headlamps; these requirements influence the design of heat-dissipation solutions.
The analysis involved 158,304 measurements from 29,516 vehicles for one year, providing a substantial dataset for significant statistical inference. Temperature was measured with existing sensors located on the circuit board of each light function or combined light functions, close to the LED. The data come from vehicles in the field during driving.
The measurements were done in different ambient temperatures, based on the mean ambient temperature generally known in the country of the vehicles. The measured temperatures were grouped in six classes.
The results were presented with the percentage of time shared in each class of temperature.
Not surprisingly, BEVs show a lower temperature average than combustion-engine vehicles.
Analysis was also done with different classes of ambient temperature, showing a similar trend in each of them. A more detailed analysis demonstrated that the temperature class is directly impacted by the type of powertrain.
Another way to present the results was the use of regressions for both BEVs and ICEs headlight temperatures for the different classes of ambient temperatures, and naturally, BEVs headlight temperatures are lower by around 5 to 8 °C compared to ICEs.
These results show that BEVs are a good contributor to reduce the temperature constraints in headlamps, certainly helping to improve the performance and reliability of the headlamp systems while increasing the energy efficiency, and in some cases, allowing cheaper material costs.
Naturally, these results are based on averages, and so for a particular model of vehicle, a specific study is still needed to check the real temperatures constraints.
