Drive well, and suddenly stall!

Originally, Brother K's favorability for electric vehicles had reached 80%, until he learned a new word.

"Limited EV functionality"

This term applies only to BYD, but similar failures have occurred in many new energy vehicles, and the reason is the failure of the high-voltage system of motor vehicles.

When your vehicle dashboard says "EV function is limited", then your vehicle's power performance will be limited, and there may be no start, stall or power interruption during travel, lying in place, etc.

Doesn't seem very clear at first glance?

Never mind, let's look at a real case.

When the owner is driving on the national highway, the dashboard lights up the EV limited fault light, and then the motor output power is limited, the throttle fails, the vehicle stalls, the brakes harden, and almost rear-end.

There are also riders who commented at the bottom of the post that when your car appears to be EV restricted, don't panic and slowly pull over, and then pray that there is no big truck behind the car.

Because of the power limit, the speed of the vehicle will be reduced to 35km/h, if there is a large truck behind at this time, the situation is very dangerous.

Ok, knowing the danger of "EV restriction", let's talk about the principle of "EV restriction".

Ps. Due to the limitations of personal understanding of electrical, some professional knowledge points have been excerpted from the "Analysis of the Basic Knowledge of The High Voltage Interlocking System of New Energy Vehicles", and some errors are welcome to correct!

First of all, new energy vehicles with motors and batteries may have EV failures, that is, hybrid vehicles and pure electric vehicles. "EV restriction" is not so much a failure as a protective measure.

This system has an academic term called "high voltage interlock", the principle is to use low voltage signals to check all components connected to the high voltage harness on the electric vehicle, and to detect the electrical connection integrity of each high voltage system loop.

This protection program is activated when the high-voltage system circuit is disconnected or the integrity is compromised.

The setting of this set of protectors has three main functions:

1. It is used to detect the loosening of the high-voltage circuit (which will cause the high-voltage power failure, the whole vehicle loses power, and affects the safety of the car), and provide alarm information to the vehicle controller before the high-voltage power failure, and reserve the time for the vehicle system to take countermeasures.

2. Play a role before the vehicle is connected to the car, and the circuit is detected to be incomplete, the system cannot be powered on, so as to avoid accidents caused by problems such as virtual connection;

3. Prevent safety accidents caused by human error operation. In the process of high-voltage system operation, if there is no high-voltage interlock design, manually disconnect the high-voltage connection point, at the moment of disconnection, the entire loop voltage is added at both ends of the breakpoint, and the voltage breakdown air is arced between the two devices, although the time is short, but the energy is very high, which may cause harm to the personnel and equipment around the breakpoint.

The above three roles and the real "EV restriction" problems are basically correct, such as losing power, unable to start, etc., the third point of human factors in the actual car probability is very low.

Knowing the principle, it is clear that EV restriction is a protection procedure.

The real causes of the problem are more complex and unknowable, and there are many reasons that can cause the high-voltage interlock program to start.

And given how "high-voltage interlocking" works, a single failure can also cause the program to start.

For example, poor contact with small batteries, high-voltage electrical box problems, it may also be software problems, power battery problems, sensor problems, etc.

Even if the fuse is burned, it is possible to activate the "EV restricted" program.

u1s1, before K brother felt that the structure of electric vehicles is quite simple, is not the battery + motor + electronic control system?

But in fact, the vehicle circuit is very complex, and the difficulty of maintenance is not lower than that of fuel vehicles.

Oh, yes, and I have to clarify the fact again, such failures have occurred on multiple new energy brands.

But the name is different, Xiaopeng pipe such a problem is called "the vehicle immediately loses power, emergency pullover", Tesla directly appeared a red warning, "power has been reduced", "the vehicle is shutting down".

When your car has this type of failure, you can try restarting it in place first.

If the restart fails, it's just a matter of waiting for the trailer...

Writing an article today does not mean to black new energy vehicles, that is, I want to tell car friends that new energy vehicles have a certain probability of such failures, there are problems with assembly processes, and there are problems with hardware quality.

But all in all, it should not be the consumer who tries and makes mistakes.

Here's the car that Brother K has picked up

Whether it's spit or recommendation

We all gave our thoughts frankly

New attention to the car friends can look at it again!