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Recently updated on October 4, 2021 at 09:28 am
Battery, thermal management and charging
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The two electric compact SUVs from Audi have batteries in two different sizes, depending on the model variant. The Q4 35 e-tron2 uses a compact battery with 52 kWh net energy content (55 kWh gross). It consists of eight modules and weighs around 350 kilograms. The Q4 40 e-tron3 and the Q4 50 e-tron four4 have the large battery on board, which provides 77 kWh of energy net (82 kW gross). It is made up of twelve modules and weighs around 500 kilograms.
The battery housing: strong aluminum framework
The battery case is an aluminum construction with a scalable size. The smaller case has ten compartments and is 144 centimeters long. The large one has twelve compartments over a length of 182 centimeters and weighs around 100 kilograms. Both cases are 145 centimeters wide and 16 centimeters high. The battery case is solid to the body of the Q4 e-tron screwed, thereby increasing their rigidity. A strong all-round frame made of extruded aluminum profiles protects the battery system in the event of an accident, and an exchangeable aluminum underrun protection covers it from the road.
Both batteries work with a nominal voltage of 352 volts. Controllers, which are located in the side member of the housing, monitor the modules and cells with regard to voltage and temperature. In cooperation with the central battery management controller, they compensate for small deviations in the capacity of the individual cells. The main control unit and the connection box with its fuses are mounted in the rear area of the battery system. In the event of a serious accident, the current flow to all other high-voltage components is immediately interrupted.
Two cycles: thermal management
The thermal management of the compact electric SUV consists of two coolant circuits. One of them controls the temperature of the electric machines, their power electronics, the onboard charger and the DC / DC converter, which connects the 12-volt electrical system to the high-voltage system. A low-temperature circuit is connected to this medium-temperature circuit, which only supplies the traction battery. The cooling medium - a mixture of water and glycol - flows through the flat channels in the base plate and thus temperature-regulates the cell spaces from below. A thermally conductive paste creates the thermal connection. When the outside temperature is low, a high-voltage heater ensures that the coolant is heated up quickly.
Stable temperature conditions: more power while driving and charging
Thermal management aims to bring the battery quickly to the ideal temperature range of around 30 degrees Celsius after starting and to keep it there until the end of the journey. This means that full power - and thus the power of the entire drive - is available after a short time, even in very cold weather. Thanks to the stable thermal conditions, the driver can also access them several times in succession or charge the battery at a high-performance HPC charging station. The complex thermal management gives the battery a long service life - Audi guarantees that it still has at least 160.000 percent capacity after eight years of operation or 70 km of driving.
The interior is air-conditioned via a refrigerant circuit with a compressor, condenser and evaporator. Valves couple it to the drive circuits when these require an unusually large amount of cooling capacity. This can be the case with high power requirements, but also with fast HPC charging with direct current, which heats the battery considerably.
Even more efficiency: the heat pump
Optionally there is for the Q4 e-tron and the Q4 Sportback e-tron a highly efficient heat pump that heats and cools the interior very quickly with the waste heat from the electrical components and the heat from the outside air. It uses environmentally friendly CO as a refrigerant2that flows through the circuit at a high pressure level. The heat pump can reduce the range loss caused by the air conditioning, especially in winter. It can best show its strengths on long journeys.
Customers of the Q4 e-tron In addition to charging, you can also control the preconditioning of the interior via the myAudi app on your smartphone. This also works when the car is not charging from the mains - but at the expense of the range. The vehicle can be started up to an outside temperature of minus 25 degrees Celsius. The optional comfort pre-air conditioning also includes the heating of the seats, the exterior mirrors and the rear window, and an exact interior temperature can be set here.
Strengths for everyday use: range and high charging capacity
All model and engine variants of the Audi Q4 e-tron and the Q4 Sportback e-tron have a CCS charging connection (CCS = Combined Charging System) on board. You can use it to charge alternating current (AC) and direct current (DC), the latter on powerful HPC columns (HPC = High Power Charging). The Q4 40 e-tron3 is able to recharge electricity for a distance of around 130 kilometers (WLTP) in around ten minutes under ideal conditions.
The optional is used for AC charging at home with 230 volts or the 400 volts recommended by Audi e-tron Compact charging system. The Q4 35 e-tron2 can charge with up to 7,2 kW of power, the other models with up to 11 kW. The e-tron The connect charging system, which will follow towards the end of the year, offers intelligent functions in conjunction with a home energy management system. These include charging at inexpensive times or with solar power if a photovoltaic system is installed.
When out and about, the standard Mode 3 cable is used for charging AC power on AC columns. The comfortable Audi e-tron On request, the Charging Service grants access to around 210.000 public charging points in 26 European countries, including 4.400 powerful HPC columns (HPC = High Power Charging). A single charge card is sufficient for this. Audi customers can choose between the city tariff for urban areas and the transit tariff for long-distance drivers; Audi pays the basic fee for the latter in the first year. In addition, in the IONITY network, you only pay 31 cents for every kilowatt hour of direct current, a price level similar to that of charging at home. The electric SUVs from Audi charge with up to 100 kW of power (Q4 35 e-tron2 ) or a maximum of 125 kW output (all other models).
