There is no doubt that the suv-buggy Audi RS Q e-tron it will be fast in the Dakar 2022, but will it also be reliable? The hybrid car will have to withstand the stresses of the Saudi desert, in particular temperatures and rocky ground, and at the same time it will have to allow the drivers to push hard on the accelerator to try to win, or at worst, accumulate the data for the next edition of the raid.
The 52 kWh high-voltage battery it is literally at the heart of the Audi RS Q e-tron. But it cannot work ‘by itself’. “With today’s battery technology it is not possible to make a fully electric off-road vehicle for the DakarAudi engineer Lukas Folie said. The engineering team led by Axel Löffler, chief designer of the RS Q e-tron, had, as they say, to start from scratch to define the basic benchmarks. The battery capacity, for example, was deemed sufficient for the maximum demand foreseen for each stage of the Dakar. While the weight of the high-voltage battery, including the cooling system, is approximately 370 kilograms: this is also an approved value.
The energy capacity and performance required, as well as the control and safety mechanisms, led Audi to use well-proven round cells as the basis of the high-voltage battery. The battery system is designed in such a way that factory drivers Mattias Ekström, Stéphane Peterhansel and Carlos Sainz feel no difference between a new and used battery, according to Audi.
Energy extraction and battery charging are always balanced over defined distances. If, for example, a difficult passage on the dunes requires maximum energy for a short time, the state of charge drops within a controlled range. The reason? The driving power of the motor-generator units on the front and rear axles it is limited to a maximum of 288 kW in total, according to the regulations. However, the energy converter can only deliver a maximum charging power of 220 kW. In extreme cases, therefore, consumption briefly exceeds energy production. “Something like this is possible for a limited time“, Says Folie. “But over a longer distance, it always results in a zero-sum game: we therefore have to adjust the power consumption so that the state of charge of the battery stays within a specific range. The absolute amount of energy available on board must always be sufficient to cover the stage of the day“.
Audi, consequently, relies on systems already used in Le Mans and in Formula E: therefore the RS Q e-tron recovers energy under braking. MGUs on the front and rear axles can convert the turning motion of the wheels into electrical energy. What seems so simple, however, requires a complex intelligent braking system, which combines the hydraulic braking function with the electric regenerative brake. We remind you that the Audi car is fitted with a total of three electric motors, with the addition of a heat engine that acts as a range extender. Reason why it is not a full electric, but rather a hybrid.
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