Most charging procedures take place at home or at the workplace – the time factor generally does not play a major role here because the car is at a standstill for a long time. By contrast, every minute counts on a long-distance journey, and charging quickly is essential, for example on a business trip. After a brief break, the car should be ready for the next stage again. The Audi engineers systematically implemented this important basic requirement for an electric car when developing the Audi e-tron.
Convincing: the charging curve
In the current competitive environment, the charging power of the Audi e-tron sets a benchmark – and not just because of the capability of High Power Charging with up to 150 kW. A high current consumption on the part of the battery over a wide charging range is, at the very least, just as important as maximum power.
The 150 kW charging curve of the Audi e-tron is characterized by continuity at a high level. Under ideal conditions, the car charges from 5 percent to 70 percent at the threshold of the maximum power before intelligent battery management lowers the current levels in order to protect the lithium-ion cells and guarantee the life cycle. A major difference from other concepts, which normally only reach their full power for a short time (peak) and lower their power considerably before reaching the 70 percent threshold. This is because the Audi e-tron continues charging at over 100 kW when it reaches 80 percent.
On a day-to-day basis, this means an elementary benefit: For a range of around 100 kilometers, the customer ideally spends less than 10 minutes at the charging terminal. The Audi e-tron reaches the 80 percent mark after just under 30 minutes. Even though it takes much longer for technical reasons, to fill the remaining 20 percent of a lithium-ion battery, fully charging the Audi e-tron at a HPC terminal takes less than 50 minutes – an outstanding characteristic compared with the competition.
Clever: the thermal management
The lithium-ion battery of the Audi e-tron has a nominal capacity of 95 kWh and has been designed for a long life cycle. Its elaborate thermal management system forms the basis for a well-balanced performance. Liquid cooling ensures that the battery’s temperature remains in the optimum range of 25° to 35 degrees Celsius, even at high stress levels or low temperatures. This technical design guarantees a high charging and driving performance and also prevents the cells from being subjected to excessive stress.
The core of the cooling system is made up of extruded profiles – visually comparable with a slatted frame – which have been affixed to the battery system from below. A newly developed, thermally conductive adhesive joins the cooling unit to the battery housing. The gap filler forms the contact between the housing and the cell modules placed in it. This filler is a thermally conductive gel that fills the space to the housing beneath every cell module. In what is a particularly efficient solution, the gel evenly transfers the waste heat produced by the cells to the coolant via the battery housing. The spatial separation of elements and battery cells carrying cooling water also increases the overall system’s safety.
Comprehensive: the charging options
In addition the charging power and battery capacity, the availability of charging terminals is a key factor in limitless, worry-free electric mobility. Audi has not left anything to chance regarding the infrastructure either. With its dedicated e-tron Charging Service, the brand with the four rings currently makes around 100,000 charging points available in 17 EU countries by card or smartphone. Standardized, country-specific prices mean that you can travel freely and easily without having to constantly compare prices. On longer trips, Audi customers charge their cars at the HPC terminals of the IONITY network at special conditions. This network is being gradually expanded and is set to have 400 stations in 2020 already. Additional HPC charging points operated by reputable providers round off the e-tron Charging Service for long-distance journeys and create additional flexibility.