What are the charging and discharging methods and technical principles of batteries?
Publish Time: 2024-12-18
The charging and discharging methods and technical principles of batteries are important contents in battery technology. The following is a detailed explanation:
1. Charging and discharging methods of batteries
Charging methods
Constant current charging method: During the charging process, the charging current remains unchanged. However, if the charging current remains unchanged in the later stage of charging, most of the current will be used to electrolyze water, resulting in excessive bubbles in the electrolyte and boiling, consuming electricity, and easily causing a large amount of active materials on the plate to fall off, causing the plate to bend, and the capacity to drop rapidly and be scrapped in advance.
Constant voltage charging method: During the charging process, the charging voltage remains unchanged. However, at the beginning of charging, the charging current is too large, and the volume change and shrinkage of the electrode active material are too fast, which affects the mechanical strength of the active material and causes it to fall off. In the later stage of charging, the charging current is too small, so that the active material deep in the plate cannot get the charging reaction, resulting in long-term undercharging, affecting the service life of the battery.
Stage constant current charging method: Combining the characteristics of constant current and constant voltage charging methods, the battery uses a larger current at the beginning of charging, a smaller current after a period of time, and an even smaller current at the end of charging, that is, constant current charging is performed with different currents in different stages. This method can extend the service life of the battery, save energy, and charge thoroughly.
Floating charging method: Batteries used intermittently or only when the AC power is off are charged in a floating charging manner. The advantage of the floating charging method is that it can reduce the gas evolution rate of the battery, prevent overcharging, and help to stabilize the voltage of the power supply system, so that the power consumption of electrical equipment is normal. However, the disadvantage is that it may cause uneven charging and undercharging of individual batteries, so regular balanced charging is required.
In addition, there are also fast charging methods such as constant current and constant cycle fast charging method, constant current and constant gas rate pulse charging and discharging polarization fast charging method, constant current and constant voltage pulse charging and discharging polarization fast charging method, constant current and voltage boost pulse charging and discharging polarization fast charging method, constant voltage and constant frequency pulse charging and discharging polarization fast charging method, terminal voltage and charging and discharging frequency selection pulse charging and discharging polarization fast charging method, and full process polarization pulse charging and discharging polarization fast charging method.
Discharge method
Before discharging, the battery pack should be charged evenly in advance to make the battery pack reach a full charge state.
Record the total floating charge voltage of the battery pack, the single cell floating charge voltage, the load current, the ambient temperature, and other setting parameters of the rectifier (or switching power supply).
Insert the quick connector of the discharge wire into the quick socket of the tester for docking (red positive and black negative), and then connect the other end of the discharge wire to the two ends of the battery pack (red positive and black negative).
Set a matching discharge current to discharge the battery pack. During the discharge process, the ambient temperature, the temperature of the battery cells and the connecting strips, and the battery with the lowest cell voltage should be monitored to see if there are any abnormal conditions.
For newly installed battery packs, the discharge end condition is that the battery pack discharge capacity reaches the rated capacity requirement or one of the cells in the battery pack reaches 1.80V.
2. Battery charging and discharging technology principle
The battery charging and discharging principle mainly involves the chemical reaction inside the battery.
Charging principle: During charging, the current provided by the external power supply reverses the chemical reaction inside the battery and converts chemical energy into electrical energy. The active material on the positive electrode releases oxygen, while the active material on the negative electrode absorbs and stores this oxygen and releases electrons at the same time. In this process, electrons flow to the negative electrode through the external circuit to form a current and complete the charging process. In simple terms, when charging a battery, electrical energy is stored as chemical energy.
Discharging principle: During discharge, the chemical reaction inside the battery proceeds forward, converting the stored chemical energy into electrical energy for use by external devices. On the positive electrode, the active material will accept electrons and release positively charged ions, while on the negative electrode, the active material releases electrons and accepts negatively charged ions. Electrons flow to the positive electrode through an external circuit to form a current, completing the discharge process. Simply put, when a battery is discharged, chemical energy is converted into electrical energy for use.
Taking a lead-acid battery as an example, its working principle is: when charging, it uses external electrical energy to regenerate the internal active material, store the electrical energy as chemical energy, and convert the chemical energy into electrical energy output again when it needs to be discharged. It uses a lead-based grid (also known as a lattice body) filled with spongy lead as the negative electrode, a lead-based grid filled with lead dioxide as the positive electrode, and dilute sulfuric acid with a density of 1.26~1.33g/ml as the electrolyte. When the battery is discharged, the metal lead is the negative electrode, an oxidation reaction occurs, and lead sulfate is generated; the lead dioxide is the positive electrode, and a reduction reaction occurs to generate lead sulfate. When the battery is charged with direct current, the two poles generate elemental lead and lead dioxide respectively. After the power source is removed, it returns to the state before discharge and forms a chemical battery.
In summary, the charging and discharging methods and technical principles of batteries are important contents in battery technology. Understanding and mastering these contents will help to better use and maintain batteries and extend their service life.
