This year, the adoption of the 800V platform in electric vehicles has accelerated significantly. With decreasing costs, the 800V platform is being applied to high-volume models, with prices now dropping to just over 200,000 yuan. Examples include the recently popular XPeng G6 and Zhiji LS6, as well as the Xiaomi Auto, whose battery pack voltage specifications were recently revealed.
The benefits of an 800V platform are well-known from automakers' marketing materials, including faster charging and longer range. However, the concept of an 800V platform might differ slightly from popular understanding. For example, the XPeng G6 long-range version, touted as having an 800V platform, only has a battery pack rated voltage of 551V; and even the Porsche Taycan, one of the earliest mass-produced vehicles using an 800V platform, only has a battery pack rated voltage of 613V for models below the 4S level, still some distance from 800V. So why isn't the battery pack voltage of 800V platform vehicles 800V?
800V Platform Definition
According to several industry insiders, the industry currently refers to electric vehicle platforms with battery pack rated voltages between 550V and 930V as 800V platforms. The rated voltage of the battery pack does not mean that the output voltage will remain stably at the rated voltage; the battery pack voltage is not fixed.
The maximum voltage of a battery pack is generally estimated by multiplying the rated voltage by the nominal voltage of the cell. Therefore, for example, the rated voltage of the XPeng G9 battery pack is 617V, and the maximum voltage can exceed 700V; the rated voltage of the Porsche Taycan GTS battery pack is 723V, and the maximum voltage can exceed 830V.
The rated voltage of the battery pack is actually closely related to many high-voltage components of the vehicle, including the compressor, drive motor, electronic control module, PTC, DC-DC, OBC, high-voltage distribution box and other components, all of which operate under this voltage.
When Porsche launched the Taycan in 2019, the related supply chain was not yet fully developed, and there were no 800V air conditioning compressors on the market. Therefore, a high-voltage converter had to be specially equipped for the air conditioning compressor to step down the 800V to 400V, which added a lot of unnecessary trouble to the overall vehicle system design.
Of course, in today's 800V models, all high-voltage components operate at the battery's rated voltage, and this is now also known as the full-range 800V platform.
Interestingly, although the industry definition is that anything above 550V is considered an 800V platform, many BYD models, such as the Han EV, used a battery pack with a rated voltage of 570V as early as the first generation, but did not promote the 800V platform.
In fact, the main selling point of the 800V platform on the market is its fast charging speed. However, in addition to high voltage, the charging current, i.e. the battery cell, is also a bottleneck that limits the charging speed. Therefore, concepts such as 3C and 4C charging rate battery packs have emerged, which mainly refer to the size of the charging and discharging current supported by the battery.
To support fast charging, some automakers are leveraging the 800V platform to achieve super-fast charging by using charging piles with specifications of 1000V/500A or higher. However, the maximum current of domestic standard charging piles is currently limited to 250A, so these automakers need to build their own supercharging piles and use liquid-cooled cables to increase the charging current.
Therefore, to adapt to national standard charging piles, BYD launched a "dual-gun charging" solution, which theoretically achieves a 250A×2 effect through two charging guns to increase the current and speed up the charging process. However, compared to other 800V models, BYD has chosen a lower battery charging rate, which may be why it hasn't promoted its 800V platform.
Considerations for Electric Vehicle Platform Voltage
Having understood the definition of an 800V platform, another question arises: why don't various car manufacturers go straight to raising the battery pack voltage to a "true" 800V?
Before 2017, the vast majority of DC charging piles in China were 500V, and at that time, 500V charging piles accounted for more than 90% of DC charging piles. However, after 2017, 750V charging piles began to be produced in large quantities and quickly became the mainstream in the market. In 2017 alone, the proportion of 750V charging piles in China rose from 14% to about 45%.
Data shows that as of August 2022, 750V charging piles accounted for over 70% of the DC charging pile market in China. While the proportion of 1000V charging piles is increasing, progress is relatively slow.
Therefore, automakers need to consider the level of charging infrastructure during the initial design phase. Currently, high-voltage platform vehicles employ different voltage boosting schemes to ensure compatibility with different charging stations, even if fast charging cannot be guaranteed, as long as the vehicle can at least be charged.
For example, BYD first adopted a solution of using a reused electric drive boost circuit to boost voltage in the Han model, which uses power devices in the inverter of the electric drive system to boost voltage during charging.
However, this method also has its problems. The charging power may be limited by the circuit's power limit, preventing it from reaching the maximum power of the charging station. Of course, some companies, like Porsche and Avita, use additional charge pump solutions to boost the voltage, but this increases the cost.
Based on the current charging infrastructure, electric vehicles need to meet two requirements: first, they need to be compatible with charging stations of 500V and below; second, under the condition of mainstream 750V charging stations, they should avoid voltage boosting as much as possible to avoid limiting charging power.
Therefore, in order to adapt to the current charging pile environment and improve the charging experience for users as much as possible, adopting a battery pack in the 550V-750V range has become the best choice for car manufacturers.
In conclusion
In fact, 1000V charging piles have already begun to be deployed rapidly in China, and it is expected that by the end of this year, the proportion of 1000V charging piles will approach 20%. The rated voltage of the battery pack of the upcoming Zhiji LS6 has reached 751V, and the rated voltage of the battery pack revealed by Xiaomi Auto is as high as 726.7V. With the upgrading of charging piles, the promotion and technological evolution of the 800V platform for electric vehicles will be further accelerated.
