Defenders amped up for the future
Motoring / 28 Feb '13, 10:39am
Since the Tata takeover the development division at Jaguar Land Rover has been gaining a reputation for lateral thinking - as in the gas-turbine power plants for the beautiful CX-75 concept - and now that attitude has been applied to electrically-powered off-roaders.
We'd have thought the ideal basis for a battery beetle crusher would have been the Range Rover Evoque; it's the smallest and lightest vehicle Land Rover makes, it has the simplest all-wheel drive system and the platform lends itself to putting a shallow battery tray under the passenger compartment, where its weight will do the most good.
Smooth, low-speed capability of the electric drive-train enables electric Defender to cover rough terrain without unnecessarily churning up the ground.
So the Solihull white-coats went ahead and built not one but seven battery-powered prototypes, to be officially unveiled at next week's Geneva motor show - all based on the Defender chassis!
There's a delicious irony in putting a cutting-edge powertrain in a soon-to-be-discontinued chassis that's only three years short of its 70th birthday but, when you look a bit closer, the results are actually quite impressive.
The original engine and gearbox of the 110 Defenders have been replaced by a 70kW, 330Nm electric motor, fed by a 300-volt, 27kWh lithium-ion battery, giving the electric Defender a range of more than 80km, according to Land Rover.
In typical, low speed, off-road use the battery can last for as much as eight hours before recharging - and than it can be reloaded by a 7kW fast charger in four hours, or a portable 3kW charger in 10 hours.
Because the electric motor delivers maximum torque from zero revs, there's no need for a gearbox; the entire transmission comprises a single speed, 2.7:1 reduction gearbox combined with the existing Defender four-wheel drive system and differential lock.
It even has a modified version of Land Rover's Terrain Response traction control system and, in keeping with Land Rover's 'tread lightly' philosophy the smooth, low-speed capability of the electric drive-train makes the electric Defenders especially well suited to climbing obstacles without unnecessarily damaging the ground.
The motor is in the middle of the chassis where the transmission used to be and the 410kg battery back is under the bonnet. A battery Defender weighs only about 100kg more than an equivalent turbodiesel model, whether with a pick-up, hard top or station wagon body.
All the major components - battery, inverter and motor - are air-cooled rather than liquid-cooled, saving a considerable amount of weight and complexity and making them a lot more robust.
The electric Defenders make the best possible use of regenerative braking, to such an extent that in hill descent mode the motor can generate 30kW of electricity. Special battery technology allows it to accept a very high rate of charge - as much as twice its capacity of 54Kw - so almost all of the regenerated energy can be recovered and stored.
As much as 80 percent of the kinetic energy in the vehicle can be recovered in this way, say Land Rover, depending on conditions.
The electric off-roaders were developed by Land Rover's advanced engineering team following successful trials of the Defender-based electric vehicle, Leopard 1. They've already been tested in extreme conditions, included pulling a 12-tonne 'road train' up a 13 percent gradient and wading to a depth of 800mm.
There are no production plans for the electric Defender but these 'magnificent seven' will go into service in specialist real world trials later this year.
Jaguar Land Rover head of research Antony Harper said: “This project is a rolling laboratory for Land Rover to assess electric vehicles, even in the most arduous all-terrain conditions. It gives us a chance to evolve and test some of the technologies that may one day be introduced into future Land Rovers.”