Why do electric cars need 800V?

Both manufacturers and car owners dream of the effect of “charging for 5 minutes and driving 200km”.

To achieve this effect, two major needs and pain points must be solved:
One, it is to greatly improve the charging performance and quickly increase the battery charging speed.
Second, it is to improve the operating efficiency of the entire vehicle and extend the driving range under the same power condition.
Here, we can use junior high school physics to briefly understand: P=UI. So if you want to increase the power, there are only two ways to increase the current or increase the voltage.
However, large currents will cause high heat losses in charging guns, cables and core components of power batteries, and the upper limit of theoretical improvement is not large. Therefore, the road to increasing current is “unreachable”, no, it should be “not very far”.
So, what about increasing the voltage?
When the system current remains constant, the charging power will double as the system voltage, that is, the peak charging speed will double, and the charging time will be greatly shortened. In addition, under the same charging power, if the voltage is higher, the current can be reduced, and the wire does not need to be so thick, and the resistance heat energy consumption of the wire is also reduced.

Therefore, if you still use the original 400V charging cable size, you can increase the charging power. This means that under the 800V platform, thinner charging cables can be used.
Huawei research shows that fast charging using 800V high-voltage mode supports maximum power charging of 30%-80% SOC, while low-voltage high-current mode can only perform maximum power charging at 10%-20% SOC, and the charging power drops very much in other ranges. fast. It can be seen that the 800V high-voltage mode can support longer fast charging.
The higher the operating efficiency of the entire vehicle, which means that under the condition of constant current, the higher the battery voltage, the greater the power of the motor, and the higher the efficiency of the motor drive.
Therefore, the 800V high-voltage platform can easily achieve high power and torque, as well as better acceleration performance. Although the improvement in energy replenishment efficiency brought by 800V to electric vehicles is qualitative, one of the biggest obstacles to the implementation of 800V is the cost issue.

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