Types of Power Batteries Commonly Used in Electric Vehicles
As we all know, traditional fuel vehicles are composed of four parts: engine, chassis, body and electrical appliances. So, do you know what the main components of an electric car are? The composition of electric vehicles can be divided into several parts: vehicle power battery, battery management system, power auxiliary facilities, motor, controller, chassis, body and electrical appliances. It can also be divided into four systems: motor drive system, chassis, body and electrical. Today, ABAIGE will talk to you about the knowledge of power batteries in electric vehicles. Understand the classification and structure of electric vehicle power batteries.power battery
Definition of power battery: Power battery is a power source that provides power for electric vehicles.
Power battery structure composition The power of a car is composed of multiple battery cells. Connect it in series and parallel, plus some such as control unit, acquisition system, cooling system, etc. to form a complete power battery. Let's first look at the diagram to understand how a complete power battery is composed.
1. Battery unit: the smallest unit that constitutes a power battery;
2. Battery module: It is formed by welding several battery cells in parallel;
3. Battery unit: composed of several battery units or battery packs connected in series;
As we all know, the power battery of Tesla electric car consists of 18,650 cells. Did you know that it has 7,000 such batteries in its entire car, which are composed as follows:
4.CSC acquisition system: There is a CSC information acquisition system inside each cell to monitor the voltage, temperature and other information of each cell or battery pack;
5. Control unit: The battery control unit is installed inside the power battery to report the voltage, current, temperature and other information of the battery to the vehicle controller, and complete the control of the power battery according to the instructions of the VCU;
6. Battery high-voltage distribution unit: installed at the positive and negative output ends of the power battery assembly, and consists of a high-voltage positive relay, a high-voltage negative relay, a pre-charging relay, a current sensor, and a pre-charging resistor.
7. Cooling system: heat the power battery to make it in the best working condition.
03 Classification of power batteries There are four common types of power batteries on the market: lead-acid batteries, nickel-metal hydride batteries, fuel cells and lithium batteries.
1. Lithium iron phosphate battery
Advantages: high safety performance, long service life, good high temperature performance, large capacity, no memory effect, light weight, environmental protection, etc. Disadvantages: low energy density, high battery manufacturing cost, low yield and poor consistency.
2. Ternary lithium battery
Advantages: high energy, long life, high rated voltage, high power endurance, low self-discharge rate, light weight, high temperature adaptability, environmental protection. Disadvantages: poor safety, no high current discharge, high price, high production requirements, high cost, high risk of high and low temperature use.
3. NiMH battery
Advantages: large discharge current, high energy density and low calorific value. Disadvantages: There is a memory effect, and it is easy to decay when charging and discharging.
4. Capacitor battery
Advantages: multiple charge and discharge, long service life, strong environmental adaptability. Disadvantages: low energy density, short cruising range.
5. Fuel cells
Advantages: high energy conversion efficiency, flexible installation points, fast load response, and strong overload capacity; disadvantages: high cost, inconvenient hydrogen storage.
There are many detailed classifications of fuel cells, which will not be introduced here. Let's briefly compare several common lithium batteries. You can have a look:
04 Packaging of electric vehicle power batteries The main styles of battery packaging are cylindrical batteries, steel/aluminum batteries and flexible polymer batteries.
05 Connection of power battery In addition, there are three main ways to connect the power battery: welding, screwing and mechanical crimping.
Welding: Common laser welding, ultrasonic welding and resistance welding.
This connection method has the advantages of low resistance, low power consumption, and high power utilization. Screw connection: Connect adjacent cells in series and parallel with screws. This connection method is mostly used for large batteries, as well as strong electrical conductivity and mechanical pressure connection: With the help of the slit-type elastic conductive structure, the tabs of the battery are directly clamped on the module. This connection method has the advantages of post-maintenance and high secondary recovery rate.