Lucid Air Dream's battery system parameters are very high, with a rated capacity of 118 kWh. But it has recently gotten into some controversy: It takes 134 kWh to charge from 0-100% in the test.

In this matter, there are some things that can be discussed with you. This battery actually reflects a lot of subsequent problems faced by the 110-130kWh large battery system.

A: Lucid Air Dream charging speed and time

The maximum charging power of this 118kWh battery can be pulled up to 300kW at a low battery SOC of 1%-20%; then as the SOC increases, when it reaches 50%, the power is about 180kW; and reduce to 90KW when 80% SOC.

(Charging power curve of Lucid Air Dream)

Overall, this power curve is very good for an 800V battery system.

If you break down according to the charging time, this type of car is expected to form a special usage habit in the future, because it takes too long to be full. The first 100 miles only takes 5.5 minutes, the second 100 miles takes 6.5 minutes, but 10 minutes for the 3rd 100 miles, and 15 minutes for the 4th 100 miles, this charging time increases quickly.

(Charging time of Lucid Air Dream)

Many consumers are confused by the fact that Electrify America charges 134 kWh in the 0-100% charging range. So, in the entire charging process, where is the 16kWh energy lost?

● Loss of DC charging pile: 3%

This depends on the power consumption of the cooling system and the efficiency of the DC charging module and the power consumption of the billing display module during the entire process. It is estimated that they add up to about 3%, or about 4kWh.

● Cooling during charging: 4%

This part of the energy is used to cool the battery during the charging process. During the charging process, the water-cooling system, 12V DCDC, charging cable, Busbar and battery all heat up.

● Battery efficiency loss: 5%

When high-current fast charging, the actual conversion efficiency of the battery is only about 95%. The difference of about 5% between input energy and available energy is the energy lost during the charging process of the battery pack, which includes the charging current, the internal resistance of the cell and the impedance under the entire conduction path, the initial cell temperature, the battery pack, etc. Effective resistance, etc., the entire energy loss is about 6.7kWh.

(Charging time and energy required)

In the test, Taycan is equipped with Performance Plus 94.3kWh (total energy) battery pack to conduct a 0% to 100% DC fast charging test. The available energy of the battery pack is 83.7kWh. Electrify America charges 94 kWh of electricity during the charging process. 10.3 kWh more than the nominal available power.

(Taycan's 84kWh available power, 94kWh is required for charging)

B: How much energy does the battery have?

The structure of the Lucid module and battery pack was explained in a previous press conference.

In fact, a total of 22 modules are used in this design, and a total of 6,600 type 21700 batteries are used. As shown in the figure below, a single module actually contains 300 pcs of 21700 batteries, and the configuration specification of the module is 30P10S. 10 Bricks can be seen below, using a plastic and Busbar theme to contain the batteries. Let's calculate the low voltage of a single module is about 36.5V, and 22 modules are 803V.

(Group form of 21700 modules)

The plug-in round wire is used between the modules to implement the connection between the modules.

(Lucid's battery module)

For such a large-capacity battery, if SiC devices are not used, there is a great loss in overall efficiency, so Lucid has also made SiC MOSFETs to improve drive efficiency. We can think that when it reaches 100kWh, if we continue to use traditional IGBTs, it will not be cost-effective in terms of efficiency. This also applies to 20kW on-board chargers.