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LOTUS, WIRELESS BATTERY MANAGEMENT SYSTEMS, AND THE FUTURE OF HIGH PERFORMANCE EVS


Patrick Morgan
"Industries around the world are pivoting toward new technologies that protect the health of the planet. Electric vehicles, and the push for clean energy, are rapidly becoming part of our daily lives. We are honored to collaborate with Lotus to deliver our groundbreaking ADI production wireless BMS for their iconic vehicle lineup.”

Patrick Morgan

Corporate VP Automotive and Sustainable Energy | Analog Devices

The global automobile industry is embracing the electric vehicle (EV) as the way of the future with an increasing number of new models “going electric.” High performance vehicle manufacturers are also joining the trend, shifting away from the internal combustion engine and racing toward electrification.

The benefits of EV technology are innumerable, including faster acceleration, greater horsepower, and higher maximum torque from the get-go.* Given the minimal moving parts, electric motors are highly reliable, require little to no maintenance, and provide very precise traction and stability control. Efficiency is also higher, with less friction and heat produced and less cooling required. Every metric for electric vehicles is better, except for one—battery weight.

Analog Devices, Inc. (ADI) has developed a wireless battery management system (wBMS)—a breakthrough technology—to reduce EV battery weight by eliminating the battery harness and associated cabling while increasing battery reliability.


Simplify and then add lightness.

Lotus Cars


To achieve its vision of a lightweight vehicle and all-electric future, Lotus (Lotus Cars), a legendary leader of high performance vehicles, adopted ADI’s wBMS for its new line of EV production cars set for delivery inside the next five years. Together, ADI and Lotus developed an integrated game-changer for the EV industry: a new ultralightweight powertrain architecture and a wireless battery management system (wBMS) for increased design flexibility, scalability, and repairability. Developed to safely propel Lotus’s future EVs, the engineering triumph will help to enable a more sustainable environment and a healthier planet.

*Target specifications based upon simulations

AT A GLANCE

COMPANY

Born from one man’s philosophy of “Form through function,” Lotus Cars delivers elegant, engineering marvels that inspire the next generation of drivers. Committed to providing a sustainable, all-electric vehicle future, Lotus is part of Geely Auto Group—the world’s fastest-growing auto manufacturer group.

APPLICATIONS

Integrate the world’s first wireless BMS into its new lightweight architecture targeting all future EV production cars. Leverage wBMS’s full hardware, software, and security solution to maximize servicing and maintenance while extending battery life and maintaining vehicle value.

CHALLENGES

Push the limits of design and technology to integrate a flexible and scalable wireless BMS into its line of electric vehicles while streamlining weight and complexity and increasing battery density and repairability.

GOAL

Work with partners at the forefront of technology to solve the most demanding design and engineering challenges and develop a future line of lightweight, high performance road EVs while ensuring safety, improving reliability, and delivering a dynamic driving experience.

wBMS: A FULLY INTEGRATED SYSTEM

ADI’s wBMS is composed of 40 hardware components. The full system is tied together with turnkey software, an end-to-end ultra-robust and secure network, and complete battery cell monitor software, including application and safety.

Components include the ADBMS6815, which accurately measures the state of charge of the battery cells and pack; the LT8618, a compact, high speed, high efficiency synchronous monolithic step-down switching regulator for power management; and the ADRF8800, which ensures robust and reliable wireless connectivity.

Portrait image of Roger Keen
“Our latest wBMS products also support battery recycling and reuse in energy storage systems to support the circular economy. Offerings from our competitors might bundle hardware, but you wouldn’t have software tying it all together. With ADI wBMS, there is no software for the customer to write, enabling them to focus on other aspects of vehicle design.”

Roger Keen

General Manager, E-Mobility | Analog Devices

A QUICK EVALUATION

“How quickly can you get me up and running and testing on the wBMS’s wireless network? That’s the first question customers ask,” said Shane O’Mahony, Product Marketing Engineer, Automotive Technology Group, ADI. “If that takes months, they just won’t do it. We’ve overcome that obstacle.”

ADI’s wBMS evaluation kit gets customers up and running fast—right out of the box. It’s a full, end-to-end wBMS, including multiple boards, software, and cybersecurity. “If you had to build a system from everybody’s components, it would take months just to get a prototype working,” said Shane O’Mahony.


wBMS enables ease of implementation, faster time to market and scalability advantages.

LOTUS: STRIVING FOR LIGHTNESS, REPAIRABILITY, AND FLEXIBILITY

For more than 70 years, Lotus has transformed the world of road and racing. The auto manufacturer wished to take advantage of ADI’s breakthrough wBMS technology and remain at the forefront of high performance vehicles and a leader in the move toward electrification.

In 2020, during the worldwide pandemic, Lotus approached ADI engineers about its future line of production EVs. Lotus sought a collaboration, adopting ADI’s wireless battery management system into its new lightweight and high performance road cars. ADI was tasked with delivering not only a lightweight wBMS, but a seamless integration that aligned with the high performance leader’s core operating model of repair and flexibility.

Discussions followed, focused on Lotus’s lightweight EV powertrain architecture and how ADI’s wBMS could help to simplify design and complexity, and result in additional weight reduction.

Wireless BMS (wBMS) is a real game-changer for the automotive industry, abolishing the need for the battery harness as well as numerous wires and connectors associated with the standard wired BMS. Analog Devices’ wireless BMS reduces pack wiring by up to 90% and decreases pack volume by up to 15%. Eliminating wires reduces vehicle weight and material costs, with the added benefit of increasing battery safety, reliability, and repairability. “The removal of the wire harness for wBMS ensures that Lotus can deliver the high performance consistent with their brand by offering a lightweight solution that optimizes performance,” said Roger Keen.

Electric Vehicle comparison of EV Battery Cable Reduction

THE COLLABORATION

ADI technical experts collaborated with Lotus design engineers to integrate the wBMS into the EV maker’s new powertrain architecture, referred to as LEVA (Lightweight Electric Vehicle Architecture).

“We worked closely with Analog Devices to integrate wBMS in our new LEVA powertrain architecture, which will be the basis for all future Lotus EVs,” said Richard Lively, Director of Propulsion and Chassis Engineering at Lotus. “The removal of the wire harness for wBMS ensures that Lotus can offer a lightweight solution that optimizes performance and is consistent with our brand of delivering powerful performance cars with exceptional handling.”

Design flexibility was critical to success. ADI met Lotus’s requirement head-on. wBMS allowed for quicker, easier, and simpler battery restructuring design, enabling a more optimized battery pack assembly and streamlined manufacturing process. The wireless nature of the battery management system provided Lotus with the design versatility to more efficiently scale future EV models.

On-site collaboration between Lotus and ADI’s design engineering teams was limited due to COVID restrictions. Not willing to be held back, Lotus and ADI ran the engagement using conference calls, advanced collaboration software, and step-by-step how-to videos.

THE FLEXIBLE LEVA ARCHITECTURE

Lotus’s LEVA powertrain architecture is designed for mid-engine high performance vehicles. The driver sits up front, behind the console and steering wheel. Everything else is behind the driver. Most of the vehicle’s weight sits in the middle of the four axles, improving weight distribution, stability, and handling. Other advantages of the design include increased safety and reduced wear. Lotus will leverage LEVA’s flexible architecture on other vehicle designs and future production models.

cutaway views for LEVA powertrain known as  Lightweight Eletric Vehicle Arcitecture
LEVA (Lightweight Electric Vehicle Architecture) offers design flexibility the freedom to tweak.

LIGHTWEIGHT VEHICLES ARE HEAVYWEIGHT CONTENDERS

Innovative engineering and breakthrough technologies enable Lotus to realize outstanding performance through light weight. Reducing the car’s mass is the most effective means of achieving a true connection between driver, car, and road. “Lotus’s primary focus during the ADI engagement was removing the wires and keep everything lightweight while maintaining optimal BMS performance,” said Shane O’Mahony.

Eliminating the electric battery pack’s wiring harness takes weight out of the vehicle, as you are removing wires and connectors. Battery pack unharnessing also improves reliability as the associated cables and connectors are notoriously points of failure for the system. An added benefit—an untethered battery pack is better suited for design flexibility and scalability.

Portrait image of Shane O'Mahony
“Weight is a killer of high performance sports cars.”

Shane O'Mahony

Product Marketing Engineer, Automotive Technology Group | Analog Devices

FLEXIBILITY AND THE FREEDOM TO DESIGN

How do you design-in the battery pack once you’ve optimized the entire vehicle architecture for high performance?

Flexibility in battery restructuring is critical, particularly to the engineer designing the ever-changing shape of aerodynamic EVs. wBMS not only provided Lotus with a quick and easy path to develop versatility, scalability, and optimization—it offered the means to fit more batteries in the pack in a new vehicle design through the void left by harness removal. More batteries in the powertrain, under the right circumstances, translates to enhanced power performance and extended vehicle range.

“Lotus engineers are now free to design the car how they see fit, as opposed to designing the car as well as possible given the constraints of a battery harness,” said Roger Keen.

Lotus car driving on road through a scenic mountain environment

INCREASING MONITORING AND SECURITY WHILE DECREASING COMPLEXITY

A nightmare of tangled complexity would emerge if every one of the hundreds of cells in a battery pack had a wire attached to its positive and negative terminal. Thus, wired battery management systems employing limited cell wiring are incapable of monitoring each cell. State of health of the cells can’t be measured—it can only be inferred by checking the state of charge of the battery in aggregate. Low charge or dead cells escape detection.

In wireless BMS, a group of battery cells transmit a wireless signal, sending secure data to the cloud to be stored securely. Using a laptop, a Lotus technician or one’s local mechanic can drill down and see extensive information, including the state of charge and the state of health of every group of parallel cells in the battery pack. OEMs, operating from headquarters, can easily and quickly upgrade the battery software. The wBMS offers Lotus engineers flexibility without increasing complexity and cloud-grade cybersecurity.

HUMAN HANDS ARE NOT REQUIRED

With a traditional wired BMS, open space is required between battery modules for human hands to attach many wires and connectors. Wireless BMS modules have only two terminals, and modules can be packed more tightly together, increasing density and decreasing form factor. The terminals can easily be connected using thin robotic tools.

Robotic assembly translates into a denser battery pack. Battery assembly and disassembly in second life, via robotics is fast, safe, and accurate, saving both time and money for EV vehicle manufacturers such as Lotus.

Gina Aquilano
“Wireless BMS enables state of health measurement and robotic assembly and disassembly of battery packs to ensure insufficient battery cells can be identified and removed, and the pack repaired efficiently.”

Gina Aquilano

Director of Technology, Automotive | Analog Devices

REPAIRABILITY: GOING BEYOND SECOND LIFE

After years of use, when the wireless battery packs are capacity reduced and no longer ideal for optimum EV power performance, they can easily be repurposed for use in clean and sustainable second-life applications, such as less demanding energy storage systems and power grids around the world. “Spent” EV batteries have the potential of delivering the promise of an electrified future by storing excess solar and wind power.

“It’s an unsustainable business model to replace the entire battery pack every time a single cell or group of cells lose their capacity prematurely,” said Richard Lively, Director of Propulsion and Chassis Engineering, Lotus Cars. “ADI’s wBMS enables a quick, easy, and cost-effective solution to our repairability requirement.”


Repairability is key to keeping an EV battery and EV on the road.

Lotus Cars


Lotus doesn’t put a half-life on any of its vehicles—many are still on the road after 25 or 30 years as classic cars, creating a conundrum for the manufacturer. A car with virtually no half-life requires that you keep it up and running “forever” while maintaining the batteries at optimum performance throughout the vehicle’s lifetime.

With wBMS, serviceability is easier and faster for both road vehicles and trackside since the battery modules only have two terminals (positive and negative) and are software programmable for quick and convenient over-the-air updates. The cell controller lives with the battery module for life as one serviceable unit, furthering the simplified service model.

The repair business model is anything but new. It’s an essential cornerstone in almost every industry today, from homes to appliances, to tooth restoration. EV battery repair will also generate a significant business opportunity for local mechanics, spare part distributors, and OEMs. Its impact on a sustainable environment is vast.

“No other BMS competitor offers the same capability as Analog Devices to repair the battery. Repairability will help to set Lotus apart from other EV makers and save as much as six tons of carbon to the environment,” said Shane O’Mahony. “And it helps to ensure Lotus vehicle owners of decades of high performance driving enjoyment.”

wBMS technology showing EV battery repairability of used EV battery cells to repaired EV Cells
wBMS extends the useful life of the battery pack by enabling the identification of abnormalities in cells for easy and quick replacement, saving time and cost.

A SUSTAINABLE FUTURE AND THE MOST THRILLING DRIVE

Mindful of the consumer shift toward a greener world and dedicated to providing product life longevity and high performance, ADI and Lotus targeted lightness, repairability, and sustainability in their collaboration.

The innovative engineering effort provided a smaller footprint, reduced cabling and battery pack volume, and one flexible system (across multiple designs), making it easier to scale and quicker and safer to assemble and disassemble. A reparable battery opens up numerous business opportunities for industry and OEMs while bringing us closer to a cleaner and healthier planet.

Daring innovation and radical thinking takes another revolutionary leap forward in the next thrilling chapter of the Lotus story.

Lotus car interior and a person holding sterring wheel driving on a country road