28/5/11

Overview: Rolls-Royce Phantom 102EX

While Rolls-Royce is undeniably a province of Greater BMW, it would be wrong to suggest that Munich fails to understand the uniqueness of its well-to-do outpost.

You can take that statement — as it was meant — to mean different things. The most obvious is that Rolls-Royce’s customers number among the happily dwindling few who do not appear to give a tinker’s cuss about the damage their chosen mode of transport does to the environment. We also mean that the Company’s construction methods are antiquated and rare, the results are marvellous to look at and touch, and driving a Rolls-Royce is still a remarkable experience — if you can put out of mind, just for long enough, the extraordinary waste and pollution that every revolution of that big petrol engine represents.

We have always thought that a turbodiesel would well suit the Phantom and its usual urban environment. But BMW’s most powerful such engine is the 740d’s three-litre straight-six, a mere waif offering 306PS and 600Nm: that’s a long way short of the Phantom’s 460PS and 720Nm. With Audi’s splendid V8 out of bounds, that doesn’t leave much.

It’s all a bit academic in any case: a Rolls-Royce buyer would never opt for a diesel engine. To do so would suggest money worries or left-wing influences.

But that’s all in the present day. Let’s hypothesise. It could well be that, at some time in the future (perhaps not all that far in the future), Rolls-Royce’s customers find themselves painted into a corner, with large petrol engines rendered uneconomic even for the very rich. With the cars spending much of their time in town, and with mechanical refinement a priority, we find ourselves with the perfect candidates for electric traction.

And so it was that Rolls-Royce embarked on the Phantom experimental electric vehicle project, otherwise known as 102EX. The Company has the full support of BMW, but not its active participation: BMW has its own agenda when it comes to alternative drivetrains and urban transport, not least because its customers’ demands are profoundly different from those of Rolls-Royce buyers.

Power electronics.

The 102EX is a battery electric vehicle, the first in the ultra-luxury segment. It has been put together more-or-less ad hoc by Rolls-Royce engineers, using components available off-the-shelf from specialist suppliers. The intention is to test, very cautiously, the reactions to the electric Phantom from owners, enthusiasts, members of the public and the media. Although the 102EX is also a test-bed to a certain degree, it is not a ‘real’ prototype, and it will not directly form the basis of Rolls-Royce’s first electric car. The experimental car will, however, be on an impressive world tour, taking in Europe, the Middle East, Asia and North America: comments from interested parties will inform Rolls-Royce’s future decisions as to alternative drivetrains.

The most important questions so far as serviceability are concerned are the usual ones we encounter with electric vehicles: is the range adequate? Will it run in very cold or hot weather? Will it be as reliable as a ‘normal’ car? In this case, of course, the ‘normal’ car is a normal Rolls-Royce. There is also the subjective issue of whether an electric drivetrain can deliver an ‘authentic Rolls-Royce experience’, though there doesn’t seem much doubt about that, given adequate grunt.

The 102EX uses the expected lithium-ion battery-pack — at 71kWh, it is thought to be the largest ever fitted to a road car. Peak current is 850A, delivered at 338V. Cells are of the pouch type, with nickel cobalt manganese cathode chemistry. There are five battery modules: one of 38 cells, one of 36, and three smaller modules of ten, eight and four arranged in various orientations within an irregularly-shaped unit that follows the shape of the original engine and gearbox.

Each of the 96 cells was individually tested before assembly into modules to determine its characteristics and capacity. The sub-assemblies were further tested under load to verify that the power connections between each cell perform to specification. The electronic sensing units for each group of cells were tested and calibrated before assembly and put through a temperature cycling regime designed to provoke failure of weak components. The main electronic box, which contains the switching and control gear, was tested in isolation from the other components.

Three separate charger units (of 3kW each) are fitted to the battery, allowing both single-phase charging (in 20 hours) or three-phase charging (in eight hours). An induction charger is also fitted to enable cable-free charging by way of an induction-plate mounded on the underside of the car.

The battery cells’ supplier suggests that the pack should be expected to last for something over three years, were it to be used every day. Part of Rolls-Royce’s test programme is to gauge battery life in the real world.

The battery powers two electric motors mounted on the rear sub-frame: these are connected to a single-speed transmission with an integrated differential.

Each motor is rated at 197PS, so the total system power is 394PS. The maximum torque is 800Nm. These outputs compare with 460PS and 720Nm for the standard Phantom. It’s worth bearing in mind, of course, that an electric motor produces its maximum torque from the first revolution, whereas the Phantom’s V12 needs 3500rpm.

Nickel cobalt manganese cathode chemistry is — in automotive terms — Nissan’s baby at present, though a number of labs and companies have worked on it. It has a capacity of around 230Wh/kg at operating voltages, a high energy density compared with other cathode chemistries. (We can’t quote figures, because it is impossible to compare like with like.) In practice, the Phantom EE runs for 100 miles or so before it needs to be recharged.

Rolls-Royce claims that 60mph can be reached from a standing start in under eight seconds — this compares with 5.7s for the standard Phantom — with the maximum speed limited to 100mph.

Drive motor.

Re-charging is by way of a plug and five-pin socket, which takes the place of the normal fuel filler. The standard fuel filler cap has been replaced by a design featuring a clear window, displaying the RR logo and 102EX motif. The window frames rear-mounted, tricolour LEDs which present the car’s charging status.

When the charging lead is first plugged in, the socket is bathed in blue light. This starts to flash as charging commences. When the battery-pack is completely charged, the display turns green, then flashes green as the solenoid is disengaged. A potential fault in the system is indicated by either constant or flashing red light.

Floor covering is saddle hide.

Charging can be halted using a switch adjacent to the plug. The process can also be operated inside the vehicle using controls beneath the centre console — this is particularly useful if you are charging the car using the induction plate on the underside — more of this anon.

Paint

We don’t usually ‘do’ paint on this web-site, not least because there isn’t much that’s less under the skin. But the special paint finish that Rolls Royce cooked up for the 102EX is worth a mention, because it really is quite unusual.

Atlantic Chrome is pale metallic blue, but not just any old pale metallic blue. In fact, it uses ceramic nano particles. Under a microscope, these mimic silver metal, but in reality they are between 8000 and 80,000 times smaller than the thickness of a hair, or 1000 times smaller than the size of a normal metallic paint particle. It certainly looks different from normal metallics, with a sort of soft sheen, quite in contrast with the normal bright metallic finish we’re used to.

In all, 16 coats of paint were applied; of these, four were the ‘nano’ paint.

Detail

Inside, there have inevitably been some changes. In the instrument panel, the fuel gauge has been replaced by a battery charge indicator, and the Phantom’s quaint reserve power dial has been tweaked to show kinetic energy regeneration during overrun. (The reserve power dial on the V12 model is a delightful nonsense, displaying the extent to which the accelerator has been depressed but with the scale reversed, so that you see 100 with the pedal released and zero at full chat.)

The design of the centre console has been changed: the charging control and display are below the central arm-rest. A single switch is used to start and halt charging, while the display itself features a bright plate with an image of a battery, lit by LEDs. Reflecting the lights used in the exterior charging socket, this image changes colour according to the charge status of the car. A blue-lit battery shows the vehicle is on standard charge, while pulsating blue indicates that inductive charging is taking place. Green indicates a fully charged battery, while red indicates a potential fault in the system.

As you would expect, the interior of the Phantom is a vegetarian’s nightmare. It is worth mentioning that the leather used in the 102EX is tanned using an experimental chromium-free process. It starts with a preparation of glutardialehyde to prepare for tanning. Chestnut extract, sustainably sourced from southern Europe, and tara powder from the crushed fruit of the South American tara bush are used for drum-spun colouring. Fruits are harvested without damage to the plant and the product is finished with a combination of natural binders and high tech polymers. The process lends itself only to certain earthy colours: in the case of Phantom E.E., a chestnut colour for the seat covers and a brown for other areas such as the floor and boot lining, both of which are made of durable saddle leather.

As well as aesthetic differences, the experimental leather — known as Corinova leather — presents a number of practical benefits. It uses less paint finish than in standard chrome-tanned leather, and creates less waste. It negates the use of petrol-refined products and, with further development, it may be possible to use recycled Corinova leather in agriculture to aerate soil.

Induction charging

This involves the use of resonant inductive coupling to transfer electrical energy from an A.C. circuit in a pad on the road surface to an inductively coupled circuit underneath the car. This type of energy transfer can be quite efficient if a) the two circuits are highly resonant and at the same frequency, and b) that the car is parked in exactly the right position, aligning the two coils.

Rolls-Royce quotes an efficiency figure of 90 per cent. when measured from the mains supply to the battery, though this is will completely aligned coils.

As if we overcome the issue of aligning the car just so, we can charge the battery-pack without having to use any visible external infrastructure.

We could make one observation, regarding the Rolls-Royce specifically: that is, the likelihood that a potential owner would be unable to provide a home for the car incorporating a high-specification charging-point would seem rather distant.

The pick-up controller is an essential part of the technology. It takes power from the receiver pad and provides a controlled output to batteries. It provides an output that remains independent of the load and the separation between primary and secondary pads. Without a controller, the voltage would rise as the gap decreases and fall as the load current increases.

The primary, transmitter pad has been constructed to shield magnetic fields to prevent EMI egress to bystanders.

Footnotes

Charles Rolls, Henry Royce and Claude Johnson played their part in an electrical revolution that pre-empted the establishment of internal combustion as the dominant car engine technology.

Henry Royce had developed a career as an accomplished electrical engineer before turning his hand to car manufacturing. His business, F.H. Royce and Co., which began selling simple lights and bell sets in the 1890s, became prosperous through the design and delivery of dynamos, electric motors and industrial cranes. Royce’s many innovations include the patent for the bayonet bulb holder, a design we still use.

One of Royce’s clients was Pritchett and Gold, a company based in Feltham in Middlesex. As well as manufacturing accumulators, they had developed a two-seater electric car, at least one of which was powered by a Royce electric motor.

The Honourable Charles Rolls also toyed with electric motoring in the years before the two men met. He had negotiated for the selling rights of an electric brougham, through C.S. Rolls and Co., in Conduit Street, London, which latterly established exclusive rights to sell Rolls-Royce models. It is likely that this car was part of the City and Suburban Electric Car Project, a joint venture of two men: Paris Singer and one Claude Johnson. The project had a short life and Johnson left to join the rapidly expanding business of Rolls, latterly taking the role of managing director of Rolls-Royce. He became known as ‘the hyphen in Rolls-Royce’, with a pivotal role in the Company’s success.

Charles Rolls was on record outlining the merits of electric drivetrains, as well as raising prescient concerns about range and recharging. He regarded a model called the Columbia as the best of its type, commenting in Automobile Journal: ‘They are perfectly noiseless and clean. There is no smell or vibration and they should become very useful for town use when fixed charging stations can be arranged. But for country use I do not anticipate they will be very serviceable — at least not for many years to come.’

Later, when the first exports of petrol-powered Rolls-Royce models were made to America, some authorities refused to believe they were not electrically powered, thanks to their legendary near-silent running.

Background

The Rolls-Royce Phantom was unveiled eight years ago and is built at a then-new facility at Goodwood. It uses an aluminium spaceframe engineered by Rolls-Royce constructed from roughly 200 box-sections of extruded cast aluminium. It is manufactured by hand, using around 120m of weld. Laser instrumentation is used to check manufacturing tolerances. The completed frame is placed in a computer-guided machining platform — necessarily one of the largest in the automotive industry — where the critical points are milled. The Phantom’s body panels are made from lightweight aluminium and composite materials, and are fastened to the spaceframe without the need to provide structural support. Only the boot is steel, intended — says Rolls-Royce — to provide a 50:50 mass distribution. While we can testify that the Phantom handles well for such a huge and upright beast, we’re not entirely convinced by this explanation. We suspect that the choice of steel has more to do with crumple management in a severe rear-end collision than with mass distribution. The availability of a very unusual optional extra — the boot can be extended by the equivalent of one 85l suitcase — might also preclude aluminium construction.

Five layers of paint and clear lacquer are applied to each Phantom — seven if it’s a two-tone car — and between each application, the body is sanded by hand. After the final layer has been applied, the body is hand-polished for five hours. Single or double coachlines can be specified; almost six metres long, these are painted by hand in a process that takes three hours for each line. Rolls-Royce’s artists can also design and apply individual motifs to a customer’s Phantom.

The position of the rear seats — behind the C-pillar — and the wrap-around upholstery together negate the need for rear side-impact airbags.

An electric servo system assists in closing the doors; the rear pair are coach doors, allowing elegant entry and egress.

The Phantom’s safety and driver aids — all the usual suspects — are overseen by an Intelligent Safety and Information System (ISIS), which runs at up to 4kHz.

Normally, motive power comes from a directly-fuelled 6.7-litre V12 atmospheric petrol engine, hand-built and engineered specifically for the Phantom though derived from a BMW unit; this drives through a ZF 6HP six-speed automatic transmission. The V12 is normally a quiet engine, though it has rather a hard growl to it when pushed.

The Phantom’s Lexicon audio system uses studio-grade components. It deploys 15 speakers and a nine-channel amplifier to deliver a maximum of 420W of sound. Two subwoofers are housed within 16-litre resonance chambers in the space created by the Phantom’s double floor, while a combination of 100mm mid-range and 25mm tweeter arrays are located in the front and rear doors, on the parcel shelf and above the instrument panel. ‘Theatre configuration’ adds two 30cm monitors within the veneered picnic tables in the rear; these screens are linked to a six-DVD changer and also allow viewing of digital television, depending on local restrictions.

Bizarrely, although the leather used to trim the Phantom is stitched by hand, it is actually cut by laser. Three types of leather are used: natural grain for the seats and trims, pre-shrunk in sunlit areas, and tipped (embossed) on the centre console and door trims to provide a little variety. The leather is barrel-dyed.

Depending on a car’s specification, up to 43 wood parts are used in each Phantom. Each of these is constructed from up to 28 layers of wood, interspersed with thin sheets of aluminium to provide strength and to prevent splintering in the event of an impact. The wood veneers used are sourced from sustainable forests. Facing veneers are book-matched: this is to make sure that the grain on the left-hand side of each panel is an exact mirror image of that on the right. Not only does this symmetry apply to each panel, but also across the cabin as a whole. A customer can also specify marquetry in the woodwork.

Rolls-Royce Phantom E.E. 102EX
Battery-pack
— type
— cells
— peak output
— capacity
— mass

Li-ion (Ni-Co-Mn)
96
330kW at 850A
71kWh
640kg
Charging time 20h (single-phase)
8h (three-phase)
Motors
PS
Nm

2x197=394
2x400=800
Transmission 6.5:1 reduction gear
with integral differential
Maximum speed 100
0-100km/h <8s
Driven wheels Rear
Kerb mass 2720
PS/t 144
Nm/t 294
Length 5840
Width 1990
Height 1638
Wheelbase 3570
Track
— front
— rear

1687
1671
Drag
— Cd
— CdA

0.37
1.041m²
Brakes
— front
— rear

374v
370v
Tyres
— front
— rear

255/50R21 106W
285/45R21 109W
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