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Lucid Motors CEO Offers a Detailed Look at the Company's Advanced Battery Technology in the First Episode of its ‘Tech Talks' Video Series

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【Summary】Lucid Motors recently announced the launch of a new “Tech Talks” video series on YouTube, which provides the public an inside look at some of the company’s advanced technology. The first video features Lucid CEO and CTO Peter Rawlinson explaining more about how the company achieved an industry-leading range of over 500 miles for the Lucid Air sedan.

Eric Walz    Mar 10, 2022 6:15 PM PT
Lucid Motors CEO Offers a Detailed Look at the Company's Advanced Battery Technology in the First Episode of its ‘Tech Talks' Video Series

The Lucid Air, first electric vehicle from luxury electric automaker Lucid Motors, recently was crowned as the world's longest range production EV with an EPA rated range of 520 miles. The Air sedan was also named as the MotorTrend 2022 Car of the Year. The company achieved this two feats by designing an advanced battery and powertrain for the Lucid Air sedan.

Lucid Motors recently announced the launch of a new "Tech Talks" video series on YouTube, which provides the public an inside look at some of the company's advanced technology.

The first video of the series was just released and it features Lucid CEO and CTO Peter Rawlinson explaining more about the company's proprietary electric powertrain technology and how the company achieved an industry-leading range of over 500 miles for the Lucid Air.

Before joining Lucid, Rawlinson served as chief designer of the Tesla Model S under Elon Musk, so he knows a thing or two about electric vehicles, which makes the video all the more interesting and informative.

"I really just wanted to take you through some of the technologies that's enabled that (500-mile range) and maybe give away one or two secrets in so doing," Rawlinson said during the video's intro, which starts with an overview of the Lucid Air's battery pack.

Rawlinson provided a brief overview of the basic principles of electrical power, along with the terms commonly used to describe an EV's power output and battery pack, such as energy, watts, kilowatts (kW), kilowatt hours (kWh) and horsepower (HP). All of these terms are frequently associated with electric vehicles.

To understand how batteries power EVs, Rawlinson first explained the definition of a "joule", which is a unit of energy in the International System of Units, In scientific terms, a joule is equal to the amount of work done when a force of 1 Newton displaces an object for a distance of 1 meter in the direction of the force applied. 

As an analogy, Rawlinson demonstrated this by picking up an apple off the floor and placing it on a table that's one meter in height. The amount of energy exerted to move the apple one meter is defined as a joule. 

However, the energy required to lift an apple is much less than what an electric car is capable of, so the output of the Lucid Air Grand Touring's 112 kWh battery pack is measured in "megajoules" (1 million joules).

To calculate megajoules, the Lucid Air's battery size of 112 kWh is multiplied by 1,000 (112,000 watts). The wattage is then multiplied by 3,600 which is the number of seconds in an hour, hence the term "kilowatt hour". Multiplying wattage by the number of seconds in an hour yields 403.2, which is rounded to 400 megajoules (400 million joules) for clarity.

Going back to the apple analogy, it would need to be picked up off of the floor and moved to the table one meter 400 million times to represent the energy contained in a fully charged Lucid Air battery.

Now instead of an apple, think of this as the amount of power required to propel the Lucid Air sedan one meter down the road. There is an interesting backstory about this. 

Using this equation, Rawlinson said that during the development of the Model S, Tesla considered naming the P85 version of the electric sedan the "Mega Joule 300" based on the roughly 300 million megajoules of energy stored in its battery pack.

"It would have sounded cool, but in the end we thought no one was going to understand,'' said Rawlinson. "It's too scientific, it's too techy. People understand kilowatt hours because they're the standard unit of energy."

How Lucid Determined the Optimal Battery Size for the Air Sedan

Although some of the info that Rawlinson shared might seem too scientific, its how the company's engineering team determined the approximate size that the Air's battery pack needed to be in order to meet the company's power and range targets of 500+ miles.

A decade ago while he was still working at Tesla, Rawlinson said that the Tesla engineers determined that a reasonably efficient electric car would use around 330 Wh of energy per mile. Which raised the question, how big does the battery pack need to be to deliver 400 miles of range? 

To do the math, take an EV's efficiency of 330 kW/mi and multiply it by the desired range of 400 (miles). This equals 132,000 watts or 132 kWh. Based on this formula, the Air would need a 132kWh battery pack to travel 400 miles on a charge. But would make the battery way too heavy and the car too expensive. The added weight also reduces efficiency, which is why Lucid needed to find a balance of efficiency vs. battery pack size.

Through advancement in battery chemistries over the past decade, Rawlinson figured that Lucid's engineers could get that efficiency number down to 250 kW/mi and deliver at least 400 miles of range. To hit this target, the Lucid Air sedan would need about a 100 kWh battery. (250 * 400 miles = 100,000/1,000 = 100 kWh).

For the battery pack in the Lucid Air, the company chose cylindrical lithium ion cells from LG Chem in 21700 format (21 mm wide by 70 mm tall). Each of these cells contains roughly 17 Wh of power each. With this amount of power per cell, Lucid determined that its would need around 6,000 individual cells (6,000 * 17 Wh = 102 kWh) to achieve a range of 400 miles. 

For example, the Lucid Air Grand Touring model achieves a range of 4.6 miles per kWh, according to Rawlinson. With its larger 112 kWh battery containing 6,660 cells, it can travel roughly 515 miles per charge (4.6 * 112 = 515 miles).

But to go even further, Rawlinson also wanted to know how much range just a single cell contributes to the Air's overall range (hypothetically of course). According to his own calculations, each cell delivers 140 yards of range (420 ft).

Now that Lucid figured out how many individual cells it would need for the Air's battery, the next step was engineering the chassis to fit them all. 

lucid-air-dream-edition.jpeg

The Lucid Air sedan achieves a EPA rated range of over 500 miles.

Lucid developed an EV platform it calls "LEAP'', which stands for Lucid Electric Advanced Platform. The goal was to fit up to 6,600 cells into the LEAP using minimal space so the company could make the cabin bigger for passengers. Lucid achieved this by miniaturizing the Air's electric powertrain, including the motors and inverters and transmission, both on the front and rear of the car.

"We achieved this with our in-house drive train technology," motor said Rawlinson. "It's super compact, with the most volumetrically powered, dense system available today."

The miniature electric drivetrain also freed up additional space to fit the 6,600 battery cells in the Lucid Air Dream Edition. 

Rawlinson said that Lucid "sculpted the battery pack" around the cabin space, including eliminating the rear tunnel that normally would intrude into the cabin to accommodate a driveshaft on a RWD ICE vehicle. Lucid also doubled-stacked the battery modules under the rear seats for the Grand Touring and Dream Edition model to free up more cabin space. 

Each individual module that makes up the battery holds 300 individual 21700 cells. The Lucid Air Long Rang battery has 22 of these modules, while the Air Pure will use 18 modules. Each module is 42 volts equaling 924 volts for the Air's Long Range battery containing 6,600 individual cells.

Why did Lucid choose a 900-volt architecture for the Air when many other EVs use 400V architectures? Rawlinson said its to minimize heat losses, which all boils down to Ohm's Law. He explained that by doubling the voltage, the Air can use half the current, which in turn reduces heat loss caused by electrical resistance. For an EV, heat loss is actually wasted energy.

"There's no substitute for voltage in terms of efficiency," said Rawlinson.

However, Lucid designed its battery pack so that some modules can be removed under the back seat to save costs and free up footwell space, while still delivering a range better than most EVs for the more affordable Lucid Air Pure, which is rated at 406 miles.

The entire battery pack is surrounded by a reinforced structure to protect it from damage, which when mated to the chassis, also serves as additional structural support to protect occupants, as well as the batteries themselves.

There is more in Rawlinson's video that explains how each battery module is cooled using a liquid filled aluminum cooling structure for each one. Once installed in the Lucid Air, a computerized battery management system monitors each battery module to ensure that overheating does not occur.

The video is interesting because not only is Rawlinson CEO of Lucid Motors, as an engineer he's also the company's CTO and was responsible for many of the innovations in the Lucid Air sedan. Think of the Lucid Air as a more advanced version of the Tesla Model S sedan, which Rawlinson also worked on.

As a startup, Lucid set out to make an electric car better than the Model S. Based on the amount of battery innovation alone for the Air, it appears that Lucid succeeded in its mission.

You can watch the full video below.

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