Why do super fast charging car models need to increase their battery voltage platform to 800V？

Question: "Why do super fast charging models need to increase their battery voltage platform to 800V?" 

Answer: This question itself is a bit absurd, but for ordinary consumers, it is very practical. Super fast charging seems to be paired with 800V.

Super fast charging, a frequently used term in the mobile phone industry, I haven't researched how to define it. In short, using a super fast charging adapter to charge a phone is very fast. Correspondingly, the super fast charging for electric vehicles is also very fast, "a cup of coffee, fully charged departure". The National Standard Announcement No. 9 of 2023 approved a series of new standards related to electric vehicle charging. This series of standards is considered a super fast charging standard by the industry, and the pinyin "ChaoJi" for "super" has been designed as the logo.

In this new standard, GB/T 18487.1-2023 provides limit requirements for charging voltage and charging current, with a maximum voltage of 1250V and a maximum current of 800A. In theory, the maximum output power can reach 1250V800A=1000kW (single gun), but in practice, the maximum output current is generally at the lower limit of the constant power range, making it difficult to achieve both the highest voltage and maximum current simultaneously. The ideal state is the current charging voltage of 800A. If the charging voltage is 800V and the charging current is 800A, the charging power can only reach 640kW. Therefore, is a car model with a charging current greater than 250A and a charging voltage of around 800V called super fast charging? In GB/T 20234.3-2023, the charging current supports 800A.

The improvement of charging speed depends on the charging rate of the battery cells and the number of series connected batteries. The higher the charging power, the faster the charging speed. The charging power is equal to the charging voltage multiplied by the charging current. With the advancement of battery technology, the charging rate of battery cells has jumped from 1C to 5C. There are hundreds of parallel connected battery cells in the power battery pack. After parallel connection, the maximum allowable charging current of the battery pack increases from 250A to 600A, or even higher. The increase in charging voltage poses no technical difficulty, just connecting more battery cells in series. 100 ternary lithium battery cells connected in series have a voltage platform of around 400V, while 200 ternary lithium battery cells connected in series have a voltage platform of around 800V. For a regular 400V vehicle model, using a regular non liquid cooled charging gun head with a maximum current of 250A, the charging power is only 100kW (400V250A); For the 800V model and using a 600A liquid cooled gun head, the corresponding charging power can reach 480kW (800V600A); Charging for 1 hour, with a battery capacity of 480 kWh and a range of 2400 kilometers (assuming a range of 5 kilometers per kWh); Charging for 10 minutes can achieve a range of 400 kilometers. As the charging current increases, the conductive medium of the entire vehicle experiences greater losses. With the same charging power, the current corresponding to the 800V voltage platform is halved, and the losses caused by conductive materials such as wiring harnesses and connectors on the vehicle body are only 1/4 of those on the 400V voltage platform.