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Rolls-Royce unveils the Phantom Experimental Electric; induction charging system

Powertrain of the 102EX. Click to enlarge.

Rolls-Royce Motor Cars is unveiling the 102EX, a one-off, fully electric-powered Phantom, today at the Geneva Motor Show. (Earlier post.) The car will tour during 2011, serving as a testbed to gather research data which will be used in informing future decisions on alternative drive-trains for Rolls-Royce Motor Cars. The global drive program will include Europe, the Middle East, Asia and North America.

The Phantom Experimental Electric (EE) features the car’s aluminium spaceframe. However, the naturally aspirated 6.75-liter V12 petrol engine and 6-speed gearbox have been replaced by a 71 kWh lithium-ion battery pack and two electric motors mounted on the rear sub-frame. These motors are connected to a single speed transmission with integrated differential.

Each motor is power rated to 145 kW, giving Phantom EE a maximum power output of 290 kW and torque of 800 N·m (590 lb-ft) available over a wide band. This compares with 338 kW for standard Phantom with maximum torque of 720 N·m (531 lb-ft), delivered at 3,500 rpm.

The Li-ion cells use a nickel cobalt manganese chemistry with a gravimetric capacity of around 230 Wh/kg, a high energy density which is important in achieving an acceptable range between re-charges. Peak current from the pack is 850A, delivered at 338 VDC. Pre-launch tests suggests Phantom EE should run to a range of up to 200 km (124 miles), with top speed limited to 160 km/h (99 mph). Acceleration from 0-60 mpg takes less than 8 seconds.

The Phantom EE battery pack houses five modules of pouch cells, a 38-cell module, a 36-cell module, and three smaller ones of ten, eight and four arranged in various orientations within an irregular shaped unit. This resembles the overall shape of the original engine and gearbox.

Each of the 96 cells was individually tested before assembly into modules to determine their characteristics and capacity. 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 prior to assembly and put through a rigorous 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 to verify correct operation.

Three separate charger units (3kW each) are fitted to the battery, which allow both single-phase (20 hours) or three-phase charging (8 hours); for a passenger car this is unique. A fourth induction charger is also fitted to enable wireless charging, a technology being trialled in Phantom EE.

The battery pack would be expected to last over three years were it to be used every day. Part of the program however will be to test this assumption in a real world environment and deliver a more robust answer to the question of battery lifespan.

As part of the Phantom EE project, Rolls ROyce will test induction charging, allowing re-charging to take place without any physical connection, delivering greater convenience for owners and hinting at the potential for a network of remote charging facilities.

There are two main elements to induction charging; a transfer pad on the ground that delivers power from a mains source and an induction pad mounted under the car, beneath Phantom EE’s battery pack. Power frequencies are magnetically coupled across these power transfer pads.

The system is around 90% efficient when measured from mains supply to battery and it is tolerant to parking misalignment. For example, it is not essential to align the transmitter and Phantom receiver pads exactly for charging to take place. While pads are capable of transmitting power over gaps of up to 400mm, for Phantom EE the separation is in the region of 150mm.

The coupling circuits are tuned through the addition of compensation capacitors. Pick-up coils in the receiver pad are magnetically coupled to the primary coil. Power transfer is achieved by tuning the pick-up coil to the operating frequency of the primary coil with a series or parallel capacitor.

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

The transmitter pad has been constructed to shield magnetic fields to prevent EMI egress to bystanders and the system operates well within internationally agreed limits.

This is the first application of the technology in a GKL++ segment (super luxury vehicles priced at more than €200,000) and the battery pack is thought to be the largest ever fitted to a road car, according to Rolls.

Evaluation of the technology is an important part of the test program. However, more fundamentally, the car will seek answers to questions posed of Rolls-Royce owners: what their needs might be for the future considering factors such as range, performance and re-charging infrastructure.



The really exciting bit for me is the induction charging technology. I had not realised that they could hit 90% efficiency, I had thought that 70-80% was more like it.
This lifts the practicality of battery cars to another level.

On a different note I don't really believe in huge batteries. The charging times stretch out even with clever technologies, and the high energy density chemistry they are using doesn't have a food cycle life - 3 years is unacceptable, and the fast charge you have to use hammers it.

To me, and I know lots will disagree, optimal is to use a 12kwh or so battery, and a fuel cell stack.
A lithium titanate chemistry could then be used giving you real fast charge capability and long cycle life.
The relative inefficiency of fuel cells when powered by hydrogen by electrolysis would not matter too much as it would not be often used, smaller numbers of hydrogen pumps would be needed so reducing infrastructure costs and also you would not limit electric car owners to those having access to an electric power point.
There would seem no reason why performance or range would have to be less than the ICE Phantom especially if capacitors were used for regenerative braking and acceleration boost.
Even in detail the systems would have good synergy, with heat available from the fuel stack to provide cabin heat.

We live in exciting times, and a combination of batteries, capacitors, fuel cells and induction charging bid fair to outdo petrol cars in all criteria, not just some.


The battery pack on this car weighs 640kg:

Within that weight budget you could have a 12kwh lithium titanate battery, at 100wh/kg for 1209kg, a 290kw fuel stack at 1kw/kg, 12kg of hydrogen storage for 140kg of tanks, 200wh of capacitors for maybe 10kg.
If you allow 40miles per gallon equivalent - the Hyundai fcv gets 72mpg equivalent - you would get maybe 500 miles of range.
The weight might go up a bit as this system could provide more power than the 290kw motors give, but only the electric motors would need an increase of power not the fuel cell stack as the batteries could kick in under hard acceleration so the increased weight would be minimal, and still well within the weight budget.


Sounds pretty good Dave, cost is not an issue with something like this. Although I wonder if you could just replace the fuel cell stack with an 4/6 cylinder atkinson cycle ICE and eCVT driving the front wheels or just range extender?


Not mentioned here is the fact that the company developing the wireless charging say it should be quite feasible and economical to introduce their system in long strips just under the tarmac of the highways, so EVs can charge as they drive, arriving at their destination with a full battery!


Yeah, of course you could use an ICE RE, and that is a lot cheaper.
If Hyundai really can get the cost down enough so that they can build an 80kw SUV for $50k by 2015, then it would be a great solution for this sort of car - although not as good as the induction charging strips clett suggests.


Batteries weight could go down by as much as 50% every 5 or 6 years and so would their cost per Kwh. By 2020/2025, a 100 Kwh battery may not cost or weight much than todays 25 Kwh units.

If wireless charging systems become widespread, future BEVs may not require very large batteries. It depends if and when wireless charging systems are embedded into streets, roads and highways.


Unfortunately there are no solid grounds for expecting battery energy densities to increase in the smooth fashion your suggest.
It would take a shift to a radically different chemistry to achieve it, such as lithium air or something.
There is no way of knowing if or when they will become practical.
We know we can build fuel cells, and we know we can build induction plates.


Storage units will not stay static but will evolve at a much faster rate due to major increased in R & D in many countries. Of course, cost will also go down at a faster rate to due future mass production and applied research to find ways for lower production cost. It already happened for smaller lithium rechargeable batteries (they are 1/10 the 2006 cost) and electrified vehicle batteries will follow the same downward price curve shortly.

Shortly after 2020/2025, when large batteries production is well above 10,000,000/year, competition will bring price down to $200/Kwh or even below $100, if the value of the USD keeps going down at the current rate.


Some people irrationally try to shoehorn fuel cell technology in every situation.


71 kWh lithium-ion battery pack this is really a dream, for any future EV owner. It clearly surpassed all previous records with 50KWh packs at Paris Motor show last year... But yielding only 200KM range from that is -40% below my expectations. May be due to RR very heavy and big car formfactor ? Or a conservative assessement so they can over-achieveit ? For me the perfect EV dream would remain a 130KWh Battery pac fit in a slightly lighter SUV formfactor, and providing 500M or 600Km of full EV range. Plus, on top of that perfect full electric tracting base, an Extended Range Generator should still be mandatory, even if battery could bring best dream 500M of EV range, and it seams to be missing here, while best rechanging time is quoted to be 8H ! Means owner will need 2-3 x full days and nights to get from Paris to St Tropez in the summer... Just forget it. RR buyers won't accept to return to diligence times....
Other than that, this car sounds beautifull and RR kept a perfectly polished best-in-class image in the world, but unfortunatly my 50-75K$ maxi budget for my next car change, this year or next, won't buy it, plus I can't dream of a promo to fit my budget here.... So good luck RR with this marvel. Hope you complete it with an extended range, and improve this full EV range to at least 300Km if not the double, making sure the added extended range ICE generator can recharge the batteries while also feeding the electric engines tracting the car...(Micro-Turbines like Jaguard ?).

Henry Gibson

A range extender engine that operates on ammonia could save much battery cost and allow very fast refueling with essentially infinite range and zero emissions. Ammonia tanks can be placed anywhere gasoline can be sold. Emergency tanks could even be sold like LPG tanks or camping fuel tanks. A tiny lightweight OPOC engine generator can be used.

Sodium sulphur fuel cells can be built at far lower cost and higher efficiency than hydrogen fuel cells as no platinum metals are needed. The sodium polysulphide can be recycled at the fuel stop.

Norway with all its hydro power and sulphur from oil production should promote sodium sulphur ships. And France should install fast build CANDU reactors at every
present reactor site to provide electricity to recycle sodium polysulphide for ships and long range automobiles. The CANDU reactors with their high neutron economy can be operated on unused transuranic elements and thorium now being unused. It is even possible that aircraft could operate on sodium and sulphur.

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