Rolls-Royce unwrapped its latest experimental concept this week at the Geneva Motor Show and rather than relying on its BMW colleagues in Munich, the team from Goodwood enlisted Lotus Engineering to electrify the massive Phantom limo.
The boffins at Hethel yanked the standard 453 hp 6.75-liter V12 engine and all of the associated drive and fuel system hardware and replaced it with a tailpipe-free battery electric system. A pair of electric motors are mounted at the rear axle with a combined output of 290 kilowatts (389 horsepower) and 590 pound-feet of torque. The power electronics package sits on top of the drive unit, all of which goes where the gas tank normally resides.
The Phantom’s layout with a hood just slightly shorter than a typical aircraft carrier actually makes it ideal for packaging a battery when the V12 is absent. Thus the massive engine bay accommodates a 71 kilowatt-hour lithium ion battery weighing in at a less than svelte 1411 pounds. This is believed to be the largest battery ever installed in an electric passenger car.
The pack is comprised of 96 cells arranged in five modules that roughly conform to the shape of the original engine and transmission. Although Rolls-Royce and Lotus have not announced who the cell supplier is, the cathode chemistry is claimed to be Lithium-Nickel-Cobalt-Manganese-Oxide which is said to have a very high energy density. The cells are most likely provided by SB LiMotive, the Samsung-Bosch joint venture that is also supplying the batteries for the BMW i3 EV and i8 PHEV.
Lotus has fitted a trio of 3 kW charging units for the battery which can be used for either single-phase 220 volt charging or three-phase 440 volt charging. The downside of such a huge battery is that no matter what kind of charging you do, the process will take a while. At 220V, it will take 20 hours to fully charge, while a three-phase charge can do the job in a mere eight hours.
Since the 102EX is an experimental vehicle, it has also been equipped with a fourth charging unit that is set up for inductive charging. This 7 kW charger requires no plug, but features a receiver pad on the bottom of the car. When the Phantom is parked over a transmitter pad, it can charge even over the six inch air gap with a claimed efficiency of 90 percent. Since inductive charging typically requires very close proximity we’d be shocked (no pun intended) if this system can actually exhibit that degree of efficiency over such a large span but hopefully Lotus and Rolls-Royce are right on this one.
With such a large battery, Rolls-Royce claims the Phantom has a range of about 120 miles but its not clear what the conditions are for that claim. Given the gentle way that Phantoms are typically driven their chauffeurs, 120 miles may not be a totally outlandish claim, at least in temperate climates. Heating or cooling the voluminous cabin of a Phantom could slash that range pretty dramatically.
For the next year, Rolls-Royce will be evaluating the electric Phantom, but we would not be at all surprised to see it offered as a factory option within a couple of years. The seamless power delivery of an electric drive system is ideally suited to such a vehicle with the $325,000+ starting price of a Phantom, the cost of even a 71 kWh battery should be fairly trivial to manage.