Let me introduce you to the battery parameters of an electric car.

With the use of electric logistics vehicles and more and more mature technology, more and more users began to contact pure electric logistics vehicles. Pure electric logistics vehicles are very different from traditional diesel vehicles. Users who have been exposed to electric light cards know that the nameplate on the battery usually has several parameters, and there is generally a nominal voltage, nominal energy, or rated capacity. Wait. So what do these parameters on an electric car battery stand for?

Battery base parameters

First come to understand the most basic parameters, this is also a junior high school classroom, I believe you can understand, so simply talk.

Voltage:

According to the definition in physics, voltage is also called potential difference or potential difference. Voltage is the reason why the charge is directed to move to form an electric current, just like the "water pressure" that occurs when the water level caused by the dam is high or low.

The voltage of a power cell refers to the load voltage after the battery is loaded, also known as the operating voltage. Power cells are sometimes marked with two types of voltage values. The lower value is usually within 3-5 V, which is the voltage value of a single battery. Another voltage value that reaches several hundred values is the total voltage of the power battery.

Current:

The amount of electricity passing through any cross section of a conductor per unit of time is scientifically called an electric current. The current in the power cell refers to the charge and discharge current of the battery within a certain range, and their maximum value is called the maximum allowable current. The concept of current is similar to "current".

The current "I" value in the figure is +53A, indicating that the electrical energy is being output

The current value of the battery can be displayed on the meter. This is also an indicator of the power output. The higher the output current, the greater the power output. If the current output is negative, the electric vehicle is undergoing energy recovery at this time.

Battery discharge C rate:

Among the basic parameters of the battery, the parameter "battery discharge C rate" is estimated to be rarely known by ordinary card holders, but this is the main parameter that determines the speed of battery charging. "Battery discharge C rate" can also be called "charge and discharge ratio", charge and discharge ratio = charge and discharge current / rated capacity; For example, when a battery with a rated capacity of 100 Ah is discharged with 20A, its discharge multiplier is 0.2 C; Battery discharge C rate, 1C, 2C, 0.2 C is the battery discharge rate, they are a measure of the speed of discharge.

With regard to the "battery discharge C rate", we can also simply understand that when the battery capacity is fixed, the larger the charge and discharge ratio value, the faster the charging speed.

Second, the energy and capacity of the battery

In addition to the most basic current voltage parameters, power cells have more important "capacity" and "energy" parameters, but in fact these parameters can be used as the expression of battery capacity, all of which determine how much power the power cell can provide. range.

Capacity:

The capacity of a power cell refers to the amount of electricity that the battery can emit under certain discharge conditions. The unit is often expressed in A.h. It is equal to the product of the discharge current and the discharge time. The capacity is also divided into theoretical capacity, nominal capacity, and rated capacity. General power cells are written as "nominal capacity."

Energy:

Power cell "energy" refers to the power output of the battery in Wh or kWh under certain discharge conditions. It affects the range of electric vehicles. This is also a direct parameter for judging battery range. It can also be understood as the "fuel tank" of a traditional diesel car.

<UNK> Energy density:

"Energy density" refers to the energy that can be output per unit mass or unit volume of battery. In the application of electric vehicles, the battery "energy density" affects the vehicle quality and mileage of electric vehicles, as well as the size of the battery and the layout space.

Energy density is also one of the measures of battery subsidy. Only when the current energy density standard is met can electric vehicles receive full subsidies. At present, the energy density of passenger car subsidized models is not less than 105 Wh / kg. For batteries with high energy density, a higher subsidy coefficient is given(160 Wh / kg and above models are subsidized by 1.2 times).

III. Battery life

In addition to focusing on battery capacity, energy density, and the range of range that can be provided, battery life card friends should also pay attention. The life of the battery is related to the operating cost of the electric light card and the residual value of the electric light card. The life of the battery is usually expressed in the cycle life.

Cycle life

The cycle life refers to the number of times the battery can be recharged and discharged. That is, at an ideal temperature and humidity, charging and discharging with a rated charge and discharge current is used to calculate the number of cycles experienced when the battery capacity decays to 80 %. After the battery decays to 80 % of the capacity, it is generally recycled for large energy storage equipment.

IV. Remaining Electricity "SOC"

After the battery parameters, there is also a sign that the card friends need to understand, that is, the "SOC" remaining power displayed on the electric light card dashboard, of course, some models will use the "remaining power" directly as the logo. SOC can also be interpreted as "fuel surplus", which can clearly indicate how much mileage the vehicle has left.

"SOC", which is called "Stateof Charge", is also called residual power, which represents the ratio of the remaining capacity of the battery after discharge to the capacity of its fully charged state.

Battery Management System (BMS)

The remaining power of "SOC" is managed and estimated by the battery management system(BMS). "BMS" is mainly to ensure the efficient work of the battery, so it is also the core of battery management.

With so many parameters on the battery, what we really care about is only capacity, energy density, and cycle life. Capacity determines the range of endurance. Energy density determines battery weight and is also an important basis for subsidy standards; The battery cycle life affects how long you can use it. In addition, during the car process, "SOC" is also an important reference value for the battery status of the vehicle and can monitor the battery status at any time.

The page contains the contents of the machine translation.