Powertrain: Dynamic performance meets efficiency

The EQC (combined power consumption: 22.2 kWh/100 km; combined CO2 emissions: 0 g/km, provisional data)1, the first Mercedes-Benz representative of the new product and technology brand EQ, features an all-new drive system development. The interplay between performance and dynamism in combination with a high level of efficiency and comfort was a particular focus of the developers. The EQC has a compact electric drivetrain at each axle, giving the vehicle the driving characteristics of an all-wheel drive. Over a wide operating range, the intelligent control allows dynamic torque distribution between the two driven axles, creating the conditions for high vehicle dynamics. The asynchronous motors have a combined maximum output of 300 kW. The centrepiece of the Mercedes‑Benz EQC is the lithium-ion battery from in-house production housed in the vehicle floor. With an energy content of 80 kWh (NEDC), it employs a sophisticated operating strategy to supply the vehicle with power, enabling an electric range of more than 450 (according to NEDC, provisional figure)1.

The vehicle concept of the EQC is designed for all the requirements of a battery-electric drive system. Both the electric powertrains and the battery are tailor-made for the EQC. Tractive power is provided by an asynchronous motor at each axle. The electric motor, a fixed-ratio transmission with a differential, the cooling system and the power electronics form a highly integrated, very compact unit. To reduce power consumption and increase dynamism, the electric drivetrains are configured differently: the front electric motor is configured for best possible efficiency in the low to medium load range, while the rear one determines dynamism. Together, they generate an output of 300 kW and a maximum torque of 765 Nm.

[1] Figures for power consumption and CO2 emissions are provisional and were determined by the German Technical Service corporation. The range figures are also provisional. EC type approval and conformity certification with official figures are not yet available. There may be differences between the stated figures and the official figures.

The key drive system data: 

CO2 emissions

0 g/km

Power consumption (NEDC)

22.2* kWh/100 km

Range (NEDC)

more than 450* km

Drive system

2 asynchronous motors, all-wheel drive

Output

300 kW (408 hp)

Peak torque

765 Nm

Top speed

180 km/h (governed)

Acceleration 0-100 km/h

5.1 s

Battery

Lithium-ion

Battery energy content (NEDC)

80 kWh

Battery weight

650 kg

*provisional data

Maximum variability for more efficiency and stability

In both their drive and recuperation functions, the electric motors operate and function irrespective of the direction of rotation. On the overrun or when braking, the mechanical rotation is converted into electrical energy and used to charge the high-voltage battery (recuperation). In the interests of maximum driving stability and efficiency, the power requirement between the front and rear axle is regulated according to the driving situation. Torque shifting allows the torque to be distributed dynamically between the front and rear axles, ensuring that there is always a satisfying balance between power and efficiency. This gives the EQC the superior driving characteristics of an all-wheel drive.

Under low to medium load conditions, only the front electric motor is operated for efficiency reasons. Maximum recuperative deceleration is achieved by using both electric motors as alternators.

Extremely quiet thanks to sophisticated decoupling

Electric vehicles are commonly known to be almost silent – above all because they have no noisy internal combustion engine. However, maximum rotational speeds of around 13,000 rpm in the electric motors pose special challenges with respect to noise insulation. Mercedes-Benz engineers have achieved an impressive level of noise comfort. In the EQC the powerpacks are isolated by rubber mounts at two points: where the powerpack connects to its subframe and where the subframe connects to the body. This effective isolation is supplemented with insulation measures. As a result, the interior of the EQC is extremely quiet.

The battery: a “heart” from Saxony/Germany

The EQC is equipped with the latest generation of a lithium-ion (Li-Ion) battery serving as the energy source for both electric motors. The battery consists of 384 cells and is located in the vehicle floor, between the two axles. The battery system is modular in design, consisting of two modules with 48 cells each and four with 72 cells each. The powerful high-voltage battery has a maximum voltage of 408 V and a nominal capacity of 210 Ah, for an energy content of 80 kWh (according to NEDC).

The integral overall cooling concept of the EQC, consisting of a heat pump function and two electric PTC heater boosters, not only includes the power electronics, the electric motor and the rotor, but also the battery. The entire battery system is liquid-cooled. At low temperatures a battery heater ensures outstanding performance and efficiency (see Climate control section).

The battery is an integral part of the crash concept for the vehicle as a whole. Its low, central location also has a positive effect on the handling characteristics of the EQC (see Safety section).

The battery is produced in Germany, by the wholly-owned Daimler subsidiary Deutsche Accumotive in Kamenz/Saxony (see Production section).

As for all other high-voltage batteries, Mercedes-Benz issues a battery certificate as a commitment to the battery performance.

Charging options: Flexible and fast charging

Whether at home via a wallbox, while shopping, at work or ultra-fast on the motorway: there are various ways to supply electric vehicles with power. Intelligently networked charging solutions focussed on the mobility needs and convenience of customers are an integral part of the new product and technology brand EQ.

As standard the EQC is equipped with a water-cooled onboard charger (OBC) with a capacity of 7.4 kW, making it suitable for AC charging at home or at public charging stations. The charging time required for a full charge depends on the available infrastructure and the country-specific vehicle equipment. Charging at a Mercedes-Benz Wallbox is much faster than at a domestic power socket (see section "The intelligent services for the EQC).

It is faster still with DC charging – which is standard for the EQC – for example via CCS (Combined Charging Systems) in Europe and the USA, CHAdeMO in Japan or GB/T in China. This usually public quick-charging system expands the existing technical standard for AC charging of electric vehicles with the capacity for DC fast charging. Depending on the SoC (status of charge), the EQC can be charged with a maximum output of up to 110 kW at an appropriate charging station. In around 40 minutes, the battery can be charged from 10 - 80 percent SoC (provisional data).

Energy management: The link between the battery and the power consumers

High-voltage energy management (HV-EMM) provides the link between the battery and the HV components (electric motors, air conditioner compressor, heating elements, DC/DC converter to power the 12 V components).

The functions of HV-EMM include:

  • Determining the usable energy remaining in the battery
  • Activation and deactivation of the high-voltage components on the basis of the available energy, and with due regard for safety requirements
  • Prediction of the currently available electrical output of the powertrain
  • Coordination of the charging process between the battery and charging components
  • Calculation of the electric operating range and consumption for EQ optimised navigation

Driving modes: The driver has a choice of drive strategies

The power consumption and range of electric vehicles greatly depend on the driving style. The EQC supports its driver with driving modes that have different characteristics. In the more economical driving modes, the haptic accelerator pedal that prompts the driver to conserve power plays an important role.

The following programs are available:

  • COMFORT: Default setting; accelerator pedal characteristic supports a comfortable driving style, but also automatically becomes more dynamic depending on the driving style.
  • ECO: Driving program focused on high efficiency and low consumption.
  • MAX RANGE: Intelligent driving program that can help the driver achieve the maximum possible range.
  • SPORT: Driving program focused on the best response for the highest driving performance.
  • INDIVIDUAL: There is also an individual driving program which allows the various parameters to be adjusted separately.

One-pedal driving: manual selection of braking recuperation

The driver is also able to influence the recuperation level using so-called paddles behind the steering wheel. The paddle on the left increases the level of recuperation, the paddle on the right reduces it. The following stages are available:

  • D Auto (recuperation via ECO Assist to suit the situation)
  • D + (coasting)
  • D (low recuperation)
  • D - (medium recuperation)
  • D - - (high recuperation). This makes one-pedal driving possible, because in most situations the recuperative deceleration is enough not to require operation of the brake pedal.

ECO Assist: Intelligent efficiency through the use of sensor fusion

Predictive driving for economy - the ECO Assist assistance system comprehensively supports drivers in implementing this effective efficiency strategy: by prompting the driver when it is appropriate to come off the accelerator, e.g. because the vehicle is approaching a speed limit, and by functions such as coasting and specific control of recuperation. For this purpose, navigation data, traffic sign recognition and information from the intelligent safety assistants (radar and stereo camera) are linked and processed.

ECO Assist takes the following traffic situations and information into account in its driving recommendations and efficiency strategy:

  • Route profile (bends, junctions, roundabouts, gradients)
  • Speed limits
  • Distance from vehicles travelling ahead

ECO Assist continuously generates coasting simulations in the background: depending on the traffic situation, it computes whether the vehicle should ideally be allowed to coast with the lowest possible driving resistance with the driver's foot off the accelerator, or whether it should be decelerated so that the battery can be efficiently charged (recuperation).

Within the limits of the system, ECO Assist controls the overrun according to the situation as soon as the driver's foot leaves the accelerator. The driver is given a discreet prompt to do this by a "foot off accelerator" symbol in the media display (or, if installed, in the head-up display). At the same time, a diagram gives the driver the reason for the recommendation (e.g. "Junction ahead" or "Gradient ahead").

ECO Assist predictively computes the driving situation when deciding whether to drive with the lowest resistance or whether to recuperate. Examples include dips, brows or speed limits ahead, which the system recognises from the map data.

  • Dip: the vehicle recognises that a downhill gradient is followed by a climb, and that a speed limit is shown. The driver receives the prompt "Foot off accelerator" in good time. As soon as the driver acts on this, the vehicle continues with the drive switched off. Recuperation takes place on the downhill stretch, but only enough to ensure that the maximum permitted speed is maintained. Recuperation ends just before the lowest point in the dip, and coasting commences to maintain as much impetus as possible for the uphill stretch in the interests of energy efficiency.
  • Brow: There is a speed limit of 90 km/h before the brow of a hill, and afterwards 100 km/h. Once again the driver is prompted with "Foot off accelerator" before the brow is reached, followed by coasting when the driver complies. On the following downhill stretch, the new target speed of 100 km/h can be reached by coasting and maintained by recuperation.
  • Speed limit: When the system recognises a speed limit from the navigation data or via Traffic Sign Assist, the driver is once again prompted with "Foot off accelerator pedal". The vehicle is then gently decelerated (while recuperating) to the new speed, followed by coasting. In this way suitable speeds for junctions, roundabouts and bends are also supported.
  • Slow-moving traffic: when the radar sensors of the system recognise slow-moving vehicles ahead while coasting, coasting is automatically interrupted if necessary. Deceleration with recuperation takes place to the extent that braking action by the driver is often unnecessary. If the vehicle ahead accelerates, coasting is reactivated automatically so as to cease deceleration and maintain the current speed as much as possible. The driver operates the accelerator if needed.
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