How to test the performance and safety of lithium batteries?

With the rapid development of technology, the huge demand for mobile digital and communication equipment, the rapid development of electric tools, and the demand for large-capacity batteries for electric vehicles and energy conservation and environmental protection, the entire battery industry is thriving. However, with these developments Our demand for batteries is increasing. Today, Chuangfa will discuss with you whether the batteries we use are safe, durable, and reliable? With the continuous demand and development of the battery industry, people have paid unprecedented attention to batteries. Indeed, the greater the capacity of lithium batteries, the greater the danger. How to pass strict and reliable tests to control and ensure the safe operation of lithium batteries Improving its working life is not only a challenge for lithium battery development and manufacturers, but also a problem that needs to be fully considered when selecting batteries and designing product power characteristics when designing batteries.

The control and monitoring of the lithium battery is realized through the battery protection and control circuit (BMS). The BMS is the link between the battery and the user. The BMS (Battery Management System) is mainly to improve the utilization of the battery, prevent the battery from overcharging and overdischarging, prolong the service life of the battery, and monitor the status of the battery. With the development of the battery management system, other functions will be added. In the development and testing of the actual BMS, it is necessary to simulate the controllable battery cell to simulate the different working states of the battery and evaluate the protection and control performance of the BMS. Generally speaking, the battery management system can realize the following functions to realize the battery test:

(1) Accurately estimate the SOC:

Accurately estimate the charge of the power battery pack State (State of Charge, or SOC), that is, the remaining battery power, to ensure that the SOC is maintained within a reasonable range, to prevent damage to the battery due to overcharging or overdischarging, and to display the remaining energy of the hybrid vehicle energy storage battery at any time, namely The state of charge of the energy storage battery.

(2)Dynamic monitoring:

In the process of battery charging and discharging, real-time collection of the terminal voltage and temperature of each battery in the battery pack of electric vehicles, charging and discharging current and battery pack The total voltage prevents the battery from being overcharged or over-discharged. At the same time, the battery status can be given in time, the problematic battery can be selected, and the reliability and high efficiency of the entire battery group can be maintained, so that the realization of the remaining power estimation model becomes possible. In addition, it is necessary to establish a history file of each battery to provide information for further optimization and development of new types of electricity, chargers, motors, etc., and to provide a basis for offline analysis of system failures.

The process of battery charging and discharging usually uses a current sensor with higher accuracy and better stability for real-time detection. Generally, the current is selected according to the front-end current of the BMS to select the corresponding sensor range for proximity. Taking 400A as an example, the open-loop principle is usually adopted. Manufacturers at home and abroad use JCE400-ASS current sensors that can withstand low temperature, high temperature and strong shock. When selecting sensors, they need to meet the characteristics of high accuracy and fast response time

(3) Balance between batteries:

It is the equalizing charge of the single batteries, so that each battery in the battery pack reaches a balanced and consistent state. Equalization technology is the key technology of a battery energy management system that is currently being researched and developed in the world.