Going the distance

The Audi e-tron sets the benchmark for fast charging and takes long distances in its stride.

Fast charging and superior thermal management combine in the Audi e-tron for an electric vehicle that works in the real world.

4 June, 2019


There are any numbers of factors that effect the efficiency and practicality of electric vehicles (EVs), but perhaps the two at the top of most buyers lists are range and speed of charging. For those planning long trips, these factors are vital and they are two areas in which the Audi e-tron sets the standard amongst EVs.

The e-tron is not only the first mass-produced car that can be charged with up to 150kW of DC electricity at a fast charging terminal, but the high charging power over a large portion of the charging procedure sets a benchmark and shortens downtime. And, with its sophisticated thermal management of the battery, it ensures the performance capability regardless of the outside temperatures. 

For most people, charging the vehicle takes place at home or at work where the down time is usually not a major factor as the car is stationary. But on a long trip, the ideal is for the least the greatest range in the first instance and then the least amount of downtime possible. So, ideally after a brief break as you would take with a conventional car on a long trip, the EV should be ready for the next stage of the trip. 

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 150kW DC. 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. 

On a long trip, the ideal is for the least the greatest range in the first instance and then the least amount of downtime possible

Put in real terms, this means that for a range of around 100 kilometres, the vehicle owner ideally spends less than 10 minutes at the charging terminal

The 150 kW charging curve of the Audi e-tron is characterised by continuity at a high level. Under ideal conditions, the car charges from five 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. This is a major difference from other charging concepts, which normally only reach their full power for a short time (peak) and then lower their power considerably before reaching the 70 percent threshold. This is because the Audi e-tron continues charging at over 100kW when it reaches 80 percent. 

Put in real terms, this means that for a range of around 100 kilometres, the vehicle owner 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. 

The Australian fast charging network is growing rapidly, with companies such as Chargefox – Australia's largest public electric vehicle (EV) charging network – installing charging stations delivering at least 150 kWh and up to 350 kWh.

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 has been for optimal performance, with liquid cooling that ensures that the battery’s temperature remains in the ideal operation range of 25° to 35° Celsius, even at high stress levels or at 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 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 and this filler is a thermally conductive gel that fills the space to the housing beneath every cell module. The gel evenly transfers the waste heat produced by the cells to the coolant via the battery housing, while the spatial separation of elements and battery cells carrying cooling water also increases the overall system’s safety. 

The result is a long-lasting battery that operates in all temperatures, charges swiftly and allows long trip without the need for major layovers or disruption to the owner. In other words, it allows ‘normal’ motoring but with zero emissions.

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