Battery power misunderstanding of electric vehicle lithium battery

Looking back on 2015, the major truck manufacturers have launched their own electric trucks, which are really hundred flowers. The electric vehicles introduced by the major truck manufacturers are basically upgraded based on the existing models. Although the appearance is consistent, the internals are quite different. A complete set of power systems has been replaced with electric motors and batteries.

A complete electric vehicle system includes the vehicle controller, power electronics unit (PEU), battery management system (BMS), battery system, and drive motor (TM). Today, we will talk about the battery problem. The battery, as the power source of the electric car, has an extremely important position. To say that the battery is on strike, the car does not have to go. It is understood that most of the electric trucks on the market today use lithium batteries.

Lithium battery is widely used in mainstream

A "lithium battery" is a type of battery using a lithium metal or a lithium alloy as a negative electrode material and using a nonaqueous electrolyte solution. Lithium metal batteries were first proposed and studied by Gilbert N. Lewis in 1912. In the 1970s, M.S. Whittingham proposed and began researching lithium-ion batteries. Due to the very active chemical properties of lithium metal, the processing, storage and use of lithium metal are very demanding on the environment. Therefore, lithium batteries have not been used for a long time. With the development of science and technology, lithium batteries have become the mainstream.

Detailed explanation of electric vehicle lithium battery: battery power is also misunderstood

Lithium batteries can be roughly divided into two categories: lithium metal batteries and lithium ion batteries. Lithium-ion batteries do not contain metallic lithium and are rechargeable. The fifth-generation lithium-metal battery of rechargeable batteries was born in 1996, and its safety, specific capacity, self-discharge rate and performance price ratio are better than lithium-ion batteries. Due to its own high technical requirements, only a few companies in the country are producing such lithium metal batteries.

Standard power is not equal to actual power for safety reasons

Each battery is set to a safe value at the factory. This is from the perspective of battery safety. In the initial battery power, the manufacturer will keep a part of the power not used. The reason for doing this is entirely for security reasons. The battery should not be excessively charged and discharged. If the battery is overcharged, it is easy to induce an accident. The most typical example is the bursting accident caused by the overcharging of the battery caused by the inferior charger charging in the news. Similarly, if the battery is excessively discharged, exceeding the end voltage value of the battery discharge, and continuing to discharge, the internal pressure of the battery may increase, and the reversibility of the active materials of the positive and negative electrodes may be damaged, so that the capacity of the battery is significantly reduced. Therefore, the "safety redundancy" of the battery setting is also to protect the normal life of the battery.

Because of this, 10%-20% of the capacity in the battery is reserved as a redundant space, so that the user will feel that the actual battery power will be less than the manufacturer's nominal power.

The effect of temperature on battery capacity causes low battery capacity

For lithium batteries, the general operating temperature is between -20 degrees and 60 degrees, and the battery can achieve maximum performance between 0-40 degrees. Once the temperature of the actual operating environment of the battery is lower than 0 degrees Celsius, it will make the battery's power has dropped to some extent.

Lithium batteries are commonly used on mobile phones and have low temperature protection

Since pure electric vehicles need to be heated by vehicle air conditioners in winter, the lower the temperature, the greater the load on the air conditioning system. Therefore, it will inevitably aggravate the power consumption of the vehicle battery, so the cruising range of the pure electric vehicle in winter will be correspondingly shortened.

The battery will be attenuated and used improperly to accelerate the attenuation.

For electric vehicle users, after a long-time use of electric vehicles, the battery's power will not be affected is one of the most concerned issues for users. After a long period of use, the battery will inevitably lead to a smaller capacity. In this regard, some people have investigated the lithium battery of electric vehicles. The attenuation of the battery presents two trends. One is that the longer the mileage, the greater the attenuation; the second is that the higher the temperature, the greater the attenuation. Mileage and temperature are two important factors.

In addition, electric vehicle batteries are also attenuated when not in use. In general, the longer the mileage of the vehicle, the greater the battery power decay, and the battery will be reduced if the vehicle is stored for a long time.

It is important to achieve maximum cruising range driving habits

The average driver knows that slow acceleration and less rapid deceleration have a certain effect on the fuel consumption reduction. The more stable the car is, the more fuel is saved, and the electric car is the same. Electric vehicles should avoid sudden acceleration as much as possible. When accelerating, the motor needs a large amount of energy in a short period of time, and the release of this part of energy is not directly reflected in the acceleration, there will always be a small amount of energy will be lost in various forms. When the vehicle runs smoothly, the battery constantly outputs energy to the motor. In this process, the energy loss is much less than the rapid acceleration.

At the same time, the electric vehicle should not be decelerated during driving. The brake system of an electric vehicle can be considered to have two sets. The set is driven by the reverse drag of the motor. When the driver releases the throttle, the battery stops supplying power to the motor. At this time, the motor is dragged by the inertia of the vehicle. The electric motor becomes a generator to charge the battery, and the energy generated by the brake is converted into electric energy and stored in the battery. The other set is the brake system in the traditional sense. The brakes brake by the brake pads and the brake discs. When the driver steps on the brake pedal, the brake system works, the vehicle quickly reduces the speed, but the kinetic energy of the vehicle is on the brakes. The heat on the disk is lost, and the energy that can be recovered by the motor is greatly reduced. Therefore, the driver's driving habits and pre-judgment of the road conditions are also one of the factors affecting the cruising range of electric vehicles.

Editor's note:

With the current domestic policy tilting on electric vehicles, more electric trucks will emerge in the future, and there will be a large number of electric trucks entering the freight market, but the development of battery technology is still the biggest bottleneck in the development of electric trucks, hope that with electric trucks The popularity of the battery technology can directly promote the outbreak of battery technology. In the future, electric trucks with longer battery life and more durable batteries will be seen.

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