Recovering kinetic energy when decelerating and converting it into electrical energy greatly boosts the range of any electric vehicle. And the new Volkswagen ID.4 can rely on a particularly advanced energy recuperation strategy.
When developing an electric vehicle, engineers face a difficult question. Namely, what should happen when drivers take their foot off the right-hand pedal? Should the deceleration be exploited to convert kinetic energy into electrical energy, or should it run without generating electrical energy so that the vehicle’s momentum is used for coasting?
The answer varies greatly depending on manufacturer and model. In the case of the new E-SUV ID.41 – as well as for the ID.32 – Volkswagen opted for a more efficient strategy: when position D (Drive – the main mode), is activated (automatically upon each start), coasting has priority because any conversion of energy inevitably leads to loss.
Coasting occurs when drivers take their foot off the accelerator pedal and the car glides forward. If drivers look ahead and predict changes in traffic, this makes for a more relaxed form of driving; should they want to decelerate more, they can step on the brake pedal. In braking manoeuvres of up to around 0.25g, this activates kinetic energy recuperation.
Consequently, for most braking manoeuvres encountered in everyday driving, the electric drive motor performs the braking alone, while the wheel brakes are only activated when more deceleration is required. When this happens, the highly accurate and swift electronic management systems mean that the transition from generator-based to hydraulic braking goes almost unnoticed. These systems also ensure the rear wheels, where brake energy recuperation takes place, always have sufficient grip.
Each ID.4 features predictive Eco Assistance as standard. It analyses data from the navigation system and vehicle sensors to provide drivers with effective support in driving efficiently and in a relaxed way.
Once the car approaches a zone requiring slower speeds – such as built-up areas or bends – Eco Assistance notifies drivers to take their foot off the accelerator pedal. From this moment on, the system manages optimum coasting and energy recovery without drivers having to intervene. The ID.4 responds in a similar way when it approaches a vehicle ahead that is travelling at a lower speed.
D or B
Drivers can use the mode selector rocker switch positioned in front of the steering wheel, on the right of the instrument panel, to change from position D to position B (Brake) at any time. In this mode, the ID.4’s drive almost always recovers kinetic energy during thrust operation, but not up until the vehicle has come to a standstill.
The limit has been set at 0.13 g – enough for clearly noticeable deceleration, yet insufficient to convey the impression of just using the accelerator pedal to accelerate and brake the vehicle. This is intentional as Volkswagen does not want to confuse customers.
In some ID.4 models, the Plus sports package comes with driving profile selection, which includes the Sport profile. The Sport profile supports brake energy recuperation in position D too, but not to the same extent as in B. In some situations, the battery charge level also plays a part: after all, if it’s fully charged, it can’t store any more recovered energy.
The electric world car
The ID.4, which offers sporty, yet comfortable driving, is Volkswagen’s first all-electric SUV and the brand’s first electric world car. Its lithium-ion battery has an energy capacity of 52 or 77 kWh (net) with ranges of up to 520 kilometres (WLTP)3, while the electric drive motor generates either 125 kW (170 PS) or 150 kW (204 PS).
1) ID.4 - power consumption (NEDC) in kWh/100 km: 16.9–16.2; CO₂ emission in g/km: 0; efficiency class: A+ 2) ID.3 – power consumption in kWh/100 km (NEDC): 15.4–14.5 (combined); CO2 emissions in g/km: 0; efficiency class: A+ 3) Range determined on the rolling road test bed in accordance with the Worldwide Harmonized Light Vehicles Test Procedure (WLTP) in the most range-favourable equipment variant of the ID.4. The actual WLTP range values may differ depending on the equipment. The actual range achieved under real conditions varies depending on the driving style, speed, use of comfort features or auxiliary equipment, outside temperature, number of passengers/load, and topography.
Source: Volkswagen Newsroom