The high-voltage components are housed in a frame (2.28 m long, 1.63 m wide, 34 cm high) beneath the passenger compartment. Twelve battery cells each form a module in a cuboid-shaped aluminum housing with a total of 36 modules on two levels fit in the vehicle floor. Whilst pouch cells were used when production of the Audi e-tron began in 2018, Audi now relies on prismatic battery cells.
To ensure that the lithium-ion battery can reliably provide full power over a longer period of time and at hot outside temperatures, even during dynamic driving, an indirect cooling system holds it in the optimum temperature range. The cooling system, distinct from the cell space, consists of flat, extruded aluminum sections divided into tiny chambers. Heat is exchanged between the cells and the cooling system beneath them via a thermally conductive gel pressed beneath each cell module, which evenly transfers the waste heat from across the battery housing to the coolant.
The battery and all key parameters, such as charge status, power output, and thermal management, are managed by the battery management controller (BMC). The BMC communicates with both the electric motor controllers and the cell module controllers (CMC), each of which monitors the modules’ currents, voltage, and temperature. The battery junction box (BJB), into which the high-voltage relays and fuses are integrated, is the electrical interface to the vehicle. Data exchange between the BMC, the CMCs, and the BJB is via a separate bus system.
Increased high-level charging power
When it comes to electric vehicles, high range is one of customers’ key requirements. But on long-distance business trips or vacation, the speed at which the high-voltage battery recharges is just as crucial. Here, the Audi Q8 e-tron impresses with a charging curve, unique in its competitive environment, that runs at a high level, meaning the current flows at a high charging power, even up to a charge level of 80 percent.
Using a fast CCS (combined charging system) charger, the Audi Q8 50 e-tron reaches a maximum charging power of 150 kW. By using more charging power at a higher battery capacity, the Q8 55 e-tron and SQ8 e-tron boast a maximum charging power of up to 170 kW. For the smaller of the two batteries, it takes around 28 minutes to charge from 10 to 80 percent in one charging stop, while the larger battery takes around 31 minutes. In ten minutes at an HPC charging station, the Q8 50 e-tron and Q8 55 e-tron can recharge to a range of 123 km, while the SQ8 e-tron recharges to 104 km.
Fast charging and long battery life through thermal management
Sophisticated thermal management ensures that the battery of the Audi Q8 e-tron quickly reaches its optimum efficiency range of 25 to 35 °C and stays there while driving – from a cold start in winter to fast highway driving on hot summer days – you can accelerate several times in succession without any drop in performance. It’s also the prerequisite for high, reproducible performance at quick-charging stations. At the same time, thermal management contributes to the battery’s long service life. The control software for charging counteracts the battery’s aging process by adjusting the current and voltage according to age and remaining capacity to prevent overloading the battery during charging.
The intelligent thermal management system comprises of four circuits that can be connected in various ways as required. It cools the electric motors including their rotors, the power electronics, and the charger. In addition, the thermal management system in the Q8 e-tron regulates both the interior temperature and that of the high-voltage battery. The rotors, which reach up to 13,300 revolutions per minute during real vehicle operation, consist of magnetically conductive electrical sheets and lightweight, high-purity aluminum. Coolant flows through the inside of the shafts to ensure that the temperature does not exceed 180 degrees Celsius, whilst the stators and end shields of the electric motors are also water-cooled. The gearboxes mounted on the end shields benefit indirectly from this solution. For the electric motor on the rear axle, the coolant is supplied via a double-wall pipe and its ceramic seal on the electric motor rotor.
22 liters of coolant circulate around the 40 meters of cooling pipes in the Audi Q8 e-tron. The standard heat pump uses the unavoidable waste heat (up to 3 kW of actual power losses) from the electric motors for efficient heating and air conditioning in the interior; a system that makes concrete contributions to improved range in everyday driving.
Charging at home
The charging flap of the Audi Q8 e-tron is located on the driver’s side fender. At the push of a button, the flap moves down to reveal the port, illuminated by a white LED. Next to it is a second LED that indicates the charging status – a pulsing green light means charging is in progress, a steady green light means charging is complete. When the plug is removed, the charging flap closes automatically within five seconds.
The charging socket has space for the CCS plug for fast DC charging or the standard mode 3 charging cable for AC charging. The standard on-board charger operates with up to 11 kW of power; the new Audi Q8 e-tron charges at a home Wallbox or at a public AC charging station between around 9.15 to approximately 11.30 hours, depending on the battery size. Audi also offers an optional 22 kW AC on-board charger. A complete charge from zero to 100 percent takes approximately 4.45 hours for the battery with a capacity of 89 kWh net and around 6.00 hours for the battery with 106 kWh net. This means that much of the car’s total range is available again after a long business meeting or an evening at the theater. Customers may also choose the Audi Q8 e-tron with an additional charging socket on the right side of the vehicle, making everyday charging even more convenient, e.g. when charging at a station at the side of the road.
Access to around 400,000 charging points in 27 European countries
The new Audi charging service ensures customers can travel Europe’s most popular destinations, safely and conveniently. The successor to the e-tron charging service, Audi charging provides access to around 400,000 public charging points. At launch, the service will be available in 27 countries and by mid-2023, in 29 countries, including Germany. This enables charging at AC charging stations with up to 11 (or 22) kW of charging power as well as quick stops at high-power chargers (HPC), where the Audi Q8 e-tron charges with up to 170 kW (Q8 50 e-tron with up to 150 kW). Customers can use an RFID card to activate most charging points or by scanning a QR code in the myAudi app.
The Plug & Charge function, which is standard in the Audi Q8 e-tron, offers even more convenience. At compatible charging stations (for example, around 1,900 HPC chargers across Europe from IONITY), vehicles with the Audi charging service use an encrypted data check to authorize and activate the station automatically when the charging cable is plugged in. It’s no longer necessary for drivers to hold their RFID card up to the card reader.
Customers pay via Audi charging, with services that can be managed entirely in the myAudi app. The user’s account collects all charging and billing data, and the app also allows users to switch to a different plan; Audi charging offers the following: the Basic plan, and the Plus and Pro plans with an account maintenance fee and lower kWh prices. In the first contract year after purchasing a new all-electric model from Audi, customers who choose the Pro plan have no monthly account maintenance fee.
The Pro plan is aimed primarily at customers who use the Audi Q8 e-tron as a long-distance vehicle and frequently charge at public quick-charging stations. The monthly account maintenance fee of €14.99 pays for itself through significantly lower electricity prices at IONITY’s quick-charging stations, starting with one long charging stop per month.
Customers can still also charge at stations that are not included in the Audi charging offer. In these cases, customers are billed directly by the respective provider, for example by credit card, and not by Audi charging.
Range display and route planner: well-informed at all times
During journeys, drivers need reliable information regarding remaining range for peace of mind and to allow them to reliably plan charging stops on long-distance trips. The e-tron route planner in the Audi Q8 e-tron gives drivers the support they need by taking numerous factors into account when calculating the remaining range, including the individual driving style and the use of comfort features such as air conditioning as well as external factors including congestion, topography along the route, and outside temperatures. All of this information ensures the route planner can ideally integrate charging stops into the planned route.
The driver can control the charging schedule from within the vehicle via the Audi Multi Media Interface (Audi MMI) or before leaving via the myAudi app. Without the technical support of the navigation system and the route planner, the calculation of the remaining range relies on recent consumption values. The system also reflects driver-specific properties, such as an especially sporty or economical driving style. Briefly higher loads, e.g., due to energy-intensive passing maneuvers, are reliably averaged out, making calculations even more realistic.
For route-based range calculation, the recent consumption data is supplemented with additional data from the Audi Q8 e-tron route planner – the system considers the topography along the planned route.
In order to calculate the range as precisely as possible, the system divides the planned route into sections and assigns each stage an expected driving speed. Additional factors include congestion, but urban traffic, traffic jams, blocked traffic, speed limits, and main through roads also have a live influence on the calculation. Examples of vehicle-related factors include changes in usage behavior related to comfort features or sudden changes in driving behavior.
If the occupants switch the heating or air conditioning on or off, the system adjusts the range display accordingly. The route planner makes looking for charging stations along the route intelligent and reliable to ensure the shortest possible travel time, only as many charging stops are suggested as are necessary to reliably reach the destination. If the route or consumption changes, the system adjusts the charging stops. Two short stops to charge at a station with high-power charging points can save time, compared to one long stop at a charging station with lower-power charging points.
The route planner also takes alternative routes with better charging infrastructure into account when calculating the ideal total travel time. The system gives preference to high-power charging (HPC) stations and reflects daily updated data, such as detailed information on payment and authentication options, precise operator data, and any access restrictions.
All terms marked in the text are explained in detail in the technology lexicon at www.audi-mediacenter.com/en/technology-lexicon. The equipment, data and prices specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.