Lucid CEO personally revealed why the Lucid Air battery has a long battery life

Lucid Air is the electric vehicle with the best energy consumption and longest cruising range currently on the market. In the latest technological dialogue, Lucid CEO Rawlinson personally explained the design and the key technologies to achieve ultra-long cruising range.

The Lucid Air, which will be delivered in the fourth quarter of 2021, has the longest battery life of the current electric car on the market. The first batch of mass-produced Lucid Air Dream Edition can travel up to more than 800 kilometers, and has an amazing power of 933 horsepower. In the latest video, Lucid Motor CEO and CTO Peter Rawlinson explains how the heart of the car was designed: the battery pack.

The Lucid Air battery pack has a capacity of 112kWh, and the battery pack is composed of cells. Lucid uses 21700 Lithium batteries, but how do they decide the battery pack capacity?

“Actually, we don’t know how many batteries are enough, but the calculation is very simple.” Rawlinson pointed out that for many years they thought that the reasonable range of electric vehicles should be 400 miles (about 640 kilometers), and technological progress has made energy consumption per mile of about 400 miles. At 250Wh, multiplied, they knew the battery pack had to have 100kWh capacity.

Each 21700 battery cell has about 17~18Wh of power, and a 100kWh battery pack means that at least 6,000 battery cells are required to achieve the required power. With the goal set, it’s time for the engineers to come out. How to cram 6,600 high-pressure, high-temperature, heavy battery cells into a car?

LEAP chassis structure
Because the battery is extremely heavy, there is almost nothing to do except plug it into the bottom of the car. Therefore, the chassis design almost determines everything about electric vehicles. This is why major car manufacturers have introduced new chassis structures. Only in this way can efficient electric vehicles be built. The Lucid Air uses a skateboard design called LEAP (Lucid Electric Advanced Platform) architecture.

“Many car manufacturers have skateboard chassis, but Lucid Air has put the Space concept at the core from the very beginning.” Rawlinson said that the Space concept makes Lucid Air smaller and more streamlined in appearance, but larger and more comfortable inside. The key lies in the self-made power system.

Lucid’s permanent magnet synchronous motor is integrated with the inverter, differential, and drivetrain to form an ultra-high voltage 900V power unit that weighs only 74kg and is about the size of a hand luggage bag. Thanks to its streamlined design, the LEAP chassis pulls out a lot of space enough to accommodate a huge battery pack.

Compared with a flat battery pack in many car manufacturers, the Lucid Air battery pack is at the back, stacking two battery packs, just under the rear seat, with a designed battery pack frame, taking into account capacity, rigidity and safety.

Crowding these hot cells together is obviously dangerous, so thermal management is the most important aspect of a battery pack. The Lucid Air battery pack places the battery cells upside down, with the connectors on the bottom and the cooling device on the top. On the one hand, it improves the cooling efficiency and on the other hand, the heat source is kept away from the passengers to ensure safety.

Below the battery pack, Lucid Air puts multiple composite material shields, which also play a dual role to ensure safety. At the same time, the shield with a thickness of about 8 mm is cut into a special arc on the bottom of the car to create a wind-cut effect, making the entire vehicle The aerodynamic performance of the car has been improved.

All this is not the imagination of engineers, but comes from the experience of Lucid’s predecessor, Atieva, who has been involved in Formula E racing for many years. “Lucid Air’s battery pack can be said to be a relative of Formula E electric racing batteries after mass production and cost control.” Rawlinson believes that this is the key to building the heart of Lucid Air.

The right way to open the Lucid Air battery pack
Compared with the 400V voltage architecture used by many car manufacturers, Lucid chooses to connect all battery packs in series. 10 battery cells in the battery pack are connected in series in a group, and each battery pack has a voltage of 42V; every 30 batteries are connected in parallel to ensure the required power.

Lucid Air connects 22 battery packs in series, each with a voltage of 42V, to achieve a 924V ultra-high voltage architecture. Why such a high voltage?

“It’s a basic law of physics that when you double the voltage, you only need half the current to get the same output.” Rawlinson explained that what’s important is that when the current is halved, the energy loss is reduced to a quarter. So Lucid teamed up with charging operator Electrify America to create a 1,000V fast-charging device that charges more efficiently.

With a high-voltage fast charging device, the Lucid Air can be charged at 300kW, and it can cover 300 miles (about 480 kilometers) of battery life in about 21 minutes. However, it is not entirely true that high voltage can lead to high-speed charging.

“The voltage of each battery cell is 4.2V. Whether it is 100V or 1,000V, this battery cell can only accept 4.2V.” Rawlinson pointed out that the benefits of high-voltage architecture are not only the battery, but also other systems. For example, the Lucid Air battery uses aluminum as the connector material instead of the common copper. Although copper conducts electricity better, aluminum makes the battery pack lighter. From the perspective of the whole vehicle, the benefit of the high-voltage system is the overall effect. Not just the charging speed.

For the heat dissipation part, Lucid also has different options. For example, the battery cell is facing upwards, and the heat dissipation plate is also installed on the top. In this way, the battery is completely “butt” in contact with the heat dissipation plate for good cooling. “It is also beneficial to dissipate heat from the side, but it will sacrifice space, so we choose space first.” Rawlinson said, don’t forget that the sides of the battery cells are curved surfaces, and it is far more difficult than imagined to have perfect heat dissipation contact on the sides.

Even the heat sink Lucid is very particular about it. If you look closely at this aluminum heat sink, there are many concave-convex designs and grooves on it. In order to create turbulence when the coolant flows, it can more effectively absorb and take away more heat.

Thick and thin is Lucid’s big secret
In the end, Rawlinson disclosed that he believes that the biggest battery design secret of the Lucid Air is the connection of the battery cells. “Resistance is the ultimate enemy, but how to reduce system resistance?” Rawlinson said, coming up with a simple and clever way from years of experience in electric racing.

The positive electrode of the battery uses a thinner wire, and the negative electrode uses a thicker wire, which can greatly reduce energy loss and ensure safety at the same time. According to Rawlinson, it’s a deceptively simple design that no one else in the industry has used yet, and that’s one of the secrets to Lucid’s battery’s high efficiency.