10/1/12

Overview: Fisker Karma

Fisker Automotive is a California-based manufacturer of luxury hybrids, founded in 2007. Its cars use electric drive with petrol engines as range-extenders. Historically, a G.M. engine has been used, though the 1997cc BMW N20 unit is set to replace it shortly.

The Company has established a European office in Munich, and has stated that both the Fisker Karma and the forthcoming Project Nina lines are global vehicles with sales likely to be split equally between the U.S. and Europe (40 per cent. each), with Asia (20 per cent.) accounting for the remainder.

Presently the Company offers two models — Karma and Surf — based on a common platform.

Fisker Karma.

The Karma is driven by electric traction motors at all times, using twin rear-mounted motors. An on-board range-extending petrol engine drives a generator to power the motors when needed. The powertrain was inspired by a high-performance ‘stealth’ vehicle created for U.S. military special operations. At its heart is a 20kWh rechargeable lithium-ion battery-pack developed by A123 Systems of Watertown, Massachusetts. The battery cells use nanophosphate cathode technology. Its designers claim that it has the highest power density in W/kg of any commercially available lithium-ion battery. A cell can be continuously discharged to 100 per cent. discharge at 35°C and can also endure discharge pulses at temperatures as high as 100°C. For so notoriously temperature-sensitive a technology as lithium-ion, this is significant. The phosphate-based system has a nominal cell voltage of about 3.3V. Peak charge voltage of 3.6V is lower than for cobalt-based lithium-ion cells, and the battery does require a specific charger.

Fisker claims that the Karma’s battery-pack can be charged from a 220V wall charger in about six hours. Running on the battery alone, the Karma can cover 50 miles; after that, the range extender engine — a petrol engine mounted in the front-mid position — provides another 250 miles of range.

Integrated into its roof, the Karma possesses what Fisker plausibly claims is the world’s largest and most powerful automotive solar panel. The unit trickle-charges the battery-pack and provides unattended cabin temperature control. Apparently enough energy can be collected by the roof over the course of a year to power the Karma for nearly 200 miles, though we suspect that owners who are not fortunate enough to live in California might experience slightly less benefit!

The Karma allows the driver to select all-electric or hybrid-electric drive modes on demand. The default ‘stealth’ (!) mode is designed to maximise efficiency, giving the car its greatest range on battery power before activating the range-extender to maintain battery charge. In Stealth mode, the Karma can accelerate from zero to 60mph in 7.9s and achieve a maximum speed of 95mph.

Total peak outputs from the two traction motors are 408PS and 1330Nm. Disappointingly, only a single-speed reduction gear is used: clearly efficiency and performance would be improved with a multi-speed transmission.

By pulling the Karma’s left-hand steering wheel paddle, the driver can engage Sport mode. With Sport mode engaged, the petrol engine drives the generator permanently, allowing the peak outputs we have quoted to be achieved. In this mode, acceleration 60mph is achieved in 5.9s and the maximum speed is 125mph.

The Karma features braking-by-wire with a capacitor back-up, and what Fisker describes as a ‘fully-blended’ regenerative braking system. Using the right-hand steering wheel paddle, the driver can operate Hill Mode to vary regenerative braking effect in three steps, rather like backing off the accelerator in an electric Mini or using a hydraulic or electromagnetic retarder in a commercial vehicle. The braking kit itself is supplied by Brembo: 370mm x 34mm floating, ventilated discs are used at the front with six-piston monobloc calipers, while at the rear are 365mm x 28mm single piece, directionally ventilated rotors with four-piston calipers.

Suspension arms are aluminium and geometry is of the short-long-arm type. At the front, mono-tube coil-over dampers feature, together with a 30mm anti-roll bar. Behind are self-leveling Sachs Nivomat mono-tube coil-over dampers and a 24mm anti-roll bar. The steering set-up is oddly old-fashioned, with electro-hydraulic assistance, though it does provide variable assistance and a variable ratio.

The bodyshell, though, is pretty up-to-date, with aluminium and composite body panels mounted on an aluminium space-frame. Inside there are eight airbags; in an impact, the doors unlock, the battery-pack disconnects and the hazard lights activate.

Driver assistance systems amount to anti-lock brakes, traction control, electronic stability control, emergency braking assist, a rear-view camera and park assist.

Fisker Surf shares Karma platform.

The Karma comes with a standard 110V charger for U.S. wall sockets. The optional 220/240v ‘high-voltage’ (in the U.S.) charging station can be installed in homes. Charge times are between six and 14 hours. Fisker claims a lifecycle for the battery-pack of 10 years or 100,000 miles under normal use.

And finally, it’s truly wonderful to see an upmarket car that is available built to an animal-free specification. Along similar lines — kind of — the wood used inside is Certified Rescued Wood sourced from California wild-fires.

Fisker Karma
Length 4996
Width 1984
Height 1330
Wheelbase 3160
Track
— Front
— Rear

1692
1701
Kerb mass 2539
Fuel tank 36l
BMW N20
Swept volume 1997cc
Bore/stroke 90.1/84.0
Compression ratio 10.0:1
PS/rpm 245/5000
Nm/rpm 350/1250
VVT IE
VVL Yes
Fuel P 91
Aspiration Tts
Boost pressure 130kPa
Text and design copyright Under the Skin 2010-2011. We recommend Firefox.