As more EV technology companies get into the business of converting classic internal combustion engine (ICE) vehicles into electric vehicles (EVs), the industry is also seeing competition for the most unique— and possibly most challenging—EV conversion. One recent conversion project might be the new leader in that competition.

UK-based Electrogenic recently announced it has completed the ICE to EV conversion process of a stunning 1929 Rolls-Royce Phantom II owned by a famous customer: Jason Momoa—star of Game of Thrones, Aquaman, and Dune. Momoa also hosts a documentary series now streaming on Discovery+ and HBO’s Max called On the Roam, which features his newly converted classic car as well as the Electrogenic team of engineers and fabricators behind the conversion project.

On The Roam captures the painstaking process of converting the Phantom II, which features original coachwork by HJ Mulliner & Co., to electric drive. Working closely with Momoa, a car enthusiast who’s deeply passionate about the environment, Electrogenic gave the stately car the silent, effortless powertrain that Charles Rolls and Sir Henry Royce—both early pioneers of electric motors—would have perhaps chosen had the technology been available to them.

“In order to pull off this dream project, I had to find the right partner,” said Momoa. “I needed a team that would appreciate the storied history of this car while updating its technology. Electrogenic is all about honoring vintage cars. Making them electric without losing any of the vehicle’s character. They were the perfect fit.”

“We’re delighted to finally reveal the full details of this car to the world,” said Steve Drummond, Director, of Electrogenic. “It has been a labor of love for everyone at Electrogenic, and a lot of fun, working with Jason over the course of 18 months to bring his vision to life. Our team of engineers, programmers, and fabricators have poured their hearts and souls into Jason’s beautiful Phantom II. This is undoubtedly the most complex classic car EV conversion ever undertaken, so the stunning results really are a testament to the world-leading talents of our team.”

Electrogenic, known for its range of “drop-in” EV conversion kits for popular classic vehicles—offered in the UK, U.S., and elsewhere by its partner-installer network—modernized the “jewel of British automotive history” with a quiet, powerful electric powertrain featuring its proprietary EV technology. The car’s original aesthetics and timeless features were retained, and the conversion is said to be entirely reversible, as is the case with all its conversion projects.

The Phantom II was originally powered by a 7.7-L pushrod straight-six engine producing between 40 and 50 bhp, bolted directly to a four-speed, non-synchromesh manual gearbox. In standard configuration, Rolls-Royce claimed a top speed of “well over 80 mph.”

The gasoline engine and gearbox were carefully removed and replaced by 93 kW·h of batteries “precision-integrated” into the existing structure of the car for a range of about 150 mi (240 km) in real-world driving. They feed an electric motor mounted between the chassis rails via a custom single-speed direct drive transmission. Output is 150 kW and 310 N·m (229 lb·ft), the torque through a fixed reduction gear delivering 1000 N·m (738 lb·ft) to the propshaft. The systems are all linked and managed by custom software developed in-house by Electrogenic’s engineers.

The battery configuration is tailored specifically to the car, a process that the company said it uses in all of its EV conversions. The batteries are housed within the car’s original architecture with no modifications made to the structure. In the case of the Phantom II, Electrogenic made use of the considerable space vacated by the engine and gearbox, installing the batteries under the bonnet and between the chassis rails.

Electrogenic noted several challenges in the Phantom II conversion project.

One key challenge was devising a way to preserve and update the Phantom’s centralized, entirely mechanical, “through-flow” chassis lubrication system. This system was designed to send oil to the car’s many phosphor-bronze bushes for brake and suspension linkages, as well as other mechanical control systems—crucial to the Rolls-Royce trademark “silken drive.” The removal of the straight-six engine disrupted the complex system, but Electrogenic said it supplemented its design to ensure it continued to work as intended.

Another challenge was redesigning the original cable-operated braking system to work seamlessly with the updated EV architecture. The original brake pedal and levers sat under the bulkhead in space reoccupied by the new battery pack, and the brake servo was housed in the gearbox, which was removed. The Electrogenic team re-positioned the original brake levers and cables, even maintaining the original ratios of the mechanical balancing system, but in a new configuration.

The Phantom’s new brakes are operated by a re-engineered pedal with braking power significantly amplified by a new hydraulic system installed between the pedal and the original cable actuators. As a final touch, the Electrogenic team calibrated the brakes to work in tandem with the motor’s energy regeneration function, further enhancing braking performance and boosting efficiency and range.

Inside the car, Electrogenic worked to retain the original features of the leather and wood-lined cabin. The original controls were repurposed, as were the standard gauges. The fuel gauge, originally a vertical sight glass, is now an LED gauge. The amp meter has become a power gauge, showing the rate-of-power draw under acceleration and power harvesting under regeneration. The oil temperature gauge now shows the charger temperature, while the water temperature gauge shows the temperature of the electric motor.

The modernizations for Momoa’s car extended to the audio setup, The cabin now houses a state-of-the-art, high-end, multi-speaker HiFi system with an integrated sub-woofer and full Bluetooth connectivity. All of this is discreetly hidden from view.

“The car’s diverse elements all add up to deliver a stunning, cohesive package,” said Drummond. “It’s a delight to drive, a Phantom that performs as Rolls-Royce’s engineers of a century ago would have wanted had they possessed the technology available to us today. It is silent, effortless, and graceful.

“While transformed in terms of performance and ease of use, as with all our conversions, the car’s tuning and calibration—honed over countless test miles—have been finely honed to reflect the original character of the car. Rather than transforming it beyond all recognition, the Phantom drives like an enhanced version of its original self.”

Electrogenic engineered in different driving modes, with normal Drive, range-boosting Eco, and high-performance Sport settings. There is also a “regen doubler” setting for the regenerative braking, which the driver can deploy on long, steep descents.