Integrated Electric Rear Axle Drive – used in conjunction with the ISG Integrated Starter-Generator system (as described below) - improves both urban emissions and off-road ability.
Land Rover’s unique electric drive is different from the hybrid technology used by some 4x4 rivals. They use electric drive only to the rear axle, significantly reducing off-road capability. Integrated Electric Rear Axle Drive enhances off-road performance by augmenting rather than replacing the mechanical drive.
Off-road, the Integrated Electric Rear Axle Drive system can provide additional torque, as required. And because electric power can offer maximum torque from standstill, it is most effective from virtually zero mph/kph. This offers better low-speed control and enhanced pull-away in difficult situations – such as on slippery surfaces or when towing.
On-road, the additional low-speed torque input from the Integrated Electric Rear Axle Drive offers multiple advantages. It allows electric-powered ’traffic creep’ and low-speed acceleration up to 20mph or 32kph, without restarting the engine, benefiting fuel consumption and CO2 emissions. Whenever required, the ISG system restarts the engine, and the vehicle is then propelled by a combination of electrical and conventional engine power. The combined effect of delaying the restarting of the engine plus the continued assistance of electric drive, significantly reduces fuel consumption.
When quicker acceleration is required, the engine can be restarted immediately, so both the conventional engine and the Integrated Electric Rear Axle Drive system supply power from rest. In this case, the electric torque boost provided by the Integrated Electric Rear Axle Drive significantly improves acceleration without adversely affecting either fuel consumption or CO2 emissions.
The additional low-speed electric torque boost not only gives extra off-road ability, it also improves efficiency by using stored energy from the additional high-voltage battery system. Completely separate from the normal 12-volt battery system, this is a high capacity lithium-ion battery pack which is charged by regenerative braking energy.
The regenerative braking puts otherwise wasted braking energy back into the high-voltage storage battery system. When slowing the vehicle, pressing the brake pedal causes the driveshafts and propshaft to transfer energy from the wheels to the Integrated Electric Rear Axle Drive system, decelerating the vehicle and transferring the ’braking’ energy to the storage battery. For harder braking and for emergency stops, the conventional braking system is retained and fully operational, working in conjunction with the regenerative braking function.
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