On Sunday, 26 October 2018, Punch 2, the solar car single-handedly built by students of KU Leuven, was the first to cross the finish line in Arica, in the north of Chile. The victory is partly thanks to the battery technology of VITO/EnergyVille.
The Carrera Solar Atacama is described as the most extreme solar car race. The 2,600 km long track runs right through the bone-dry Atacama Desert, in the north of Chile, and through the Andes mountain range. “The big differences in altitude (from sea level to peaks of 3,400 metres high) and the high levels of solar radiation made this race an ultimate test for our Punch 2”, says Sam Vanherbergen, engineering student at KU Leuven and responsible for the electric drive of the solar car within the Punch Powertrain Solar Team.
The Punch 2, which left all the opposition behind in Chile, is already the seventh solar car designed and built by students of Leuven University. Every year students form a new team that draws lessons from previous races to further improve solar car technology. “The knowledge that we have acquired so far is already being applied into a new car. We want to compete for the world title in Australia in October 2019.”
A solar car generates electricity via photovoltaic cells. This power does not only drive the electromotor, but it is also stored in the on-board batteries – so that the car does not come to a standstill in the absence of sunlight. A reliable battery management system (BMS) is indispensable here. “The electrical system monitors and protects the battery so that it doesn’t break down under extreme conditions”, says Vanherbergen. In addition, the BMS indicates, accurately and in real time, how much energy is left in the batteries.”
The BMS of the Punch 2 was developed by VITO/EnergyVille. “Our BMS is one of the few systems available that can balance the battery both dynamically and actively”, says Geert Jacobs of VITO/EnergyVille. “Thanks to the balancing system, each cell can be individually recharged or discharged. This allows to make the most of the inherent capacity of the entire battery pack. The BMS ensures that all battery cells are kept in balance, while the entire battery pack is being – simultaneously – charged or discharged. Thanks to our BMS, it is therefore possible for all the individual battery cells to be not only fully charged, but also emptied to their limit.”
During a solar car race, details that seem trivial at first glance may mean the difference between victory and defeat. “With our innovative BMS, we can squeeze an extra two per cent of energy out of the batteries”, says Boudewijn Knooren of VITO/EnergyVille. “If you know that a solar car consumes ten per cent of its battery capacity each hour, this gives you a time saving of 12 to 14 minutes. During the last world championship in Australia, that was the exact average time difference between two incoming teams. We will also continue to support the Solar Team as VITO/EnergyVille, also with a view to the World Solar Challenge in Australia in October this year.
Photo credits: © Punch Powertrain Solar Team