Electric cars: for Audi the charging curve is more important than the maximum peak


When you speak of electric cars, one of the most discussed topics is certainly their charging capacity. Usually, those who own a vehicle of this type, most of the times recharge it at home. However, the issue is quite different when you have to travel long. In such contexts, the charging speed plays a very important role. The time factor, therefore, is essential, especially if you want to push for the diffusion of these means.


For Audi, to evaluate the real charging performance of an electric car, should be taken into consideration not so much the declared autonomy or the maximum power at which it can recharge, as much as the amount of kWh that can be stored per minute during the entire charging cycle. For the German manufacturer, therefore, it is very important the charging curve, not the peak. The more the car manages to maintain high power, the shorter the refueling times.

That’s why the brand wanted to work a lot on this aspect on its e-tron 55 (Here the road test) rather than providing a greater peak of charging power but with a less efficient curve. The battery-powered SUVs of the German brand, in fact, can count on a distinctive curve in order to quickly reach the peak (150 kW) than then it can be kept for a long time. Audi explains that under ideal conditions, full power is maintained between 5% and 70% of the battery capacity. (Here the guide on how to recharge an electric car)

Different electric models from other manufacturers, on the other hand, allow you to recharge with higher power peaks but then the curve decreases rapidly and, in the end, times expand. Constancy of power therefore translates into real advantages in everyday driving. From an HPC (High Power Charger) column with the Audi e-tron 55 it takes 10 minutes to add 110 km of autonomy. 80% of the accumulator capacity is reached in about 30 minutes. These advantages translate into the possibility of being able to plan long-distance journeys in the best possible way.

The battery of the Audi e-tron 55 features with a capacity of 95 kWh of which 86.5 kWh usable. The rated voltage is 396 volts. To manage the accumulators in the best way, the House of the 4 rings has set up a refined thermal system. The SUV has a system that includes 4 separate circuits, 40 meters long overall and containing 22 liters of refrigerant. These circuits combine as needed. In this way it is possible to air-condition the passenger compartment, the battery, the engines, the electronics and the charging device.

Accumulators will always be kept at a temperature between 25 and 35 degrees, in all driving conditions. During a high power DC charge, the coolant allows you to dispose of excess heat. In winter, however, the coil is always heated by the same liquid that will act as a heat exchanger. Also contributing to the thermal management of the battery pack is its constructive design. For example, the contact between the modules and the cells uses the gap filler, that is, a thermally conductive gel that transmits the heat of the cells uniformly to the battery box and then transfers it to the coolant.

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