What are the methods for estimating the state of charge of lead-acid batteries?

Lead-acid battery state-of-charge estimation method The state-of-charge estimation is an important basis for lead-acid battery charge and discharge control and balance management. As an important energy storage component, lead-acid battery performance directly affects the stable operation of photovoltaic power generation system . In order to prolong the service life of the battery and ensure the safe, reliable and economic operation of the photovoltaic energy storage system, the state of charge SOC of the battery must be accurately estimated. (1) Ampere-hour method This method detects the current from the initial time to the time, and uses the integral algorithm to obtain the charged power and the discharged power, which are compared with the rated capacity Cn and then subtracted from the initial SOC0 time to obtain the time t SOC value. The ampere method is widely used in SOC detection because of its simple detection method and easy realization. However, the ampere-hour method also has two important defects: a) a relatively accurate SOC initial value; b) the ampere-hour method is an open-loop current integration, and the battery is affected by factors such as charge and discharge rate, temperature, and aging during operation. If these factors are not considered, as time increases, the accumulated error of the ampere-hour method will become larger and larger, and an accurate SOC value will eventually not be obtained. (2) Open circuit voltage method The open circuit voltage method uses a relatively fixed functional relationship between the open circuit voltage of the battery and the SOC, and estimates the SOC by measuring the open circuit battery of the lead-acid battery. The open circuit voltage method is relatively simple, but due to the polarization application, the battery needs several hours or even ten hours of standing time to reach a stable open circuit voltage, which causes difficulties in measurement. (3) Internal resistance method The internal resistance of lead-acid batteries is divided into AC internal resistance and DC internal resistance. Regarding the lead-acid battery, its internal impedance is closely related to the capacity and integrity of the battery. Therefore, it has been proposed that the measured impedance can be used to evaluate and predict the performance of the battery. In fact, it is more difficult to accurately measure the internal resistance of the battery online. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: What are the key raw materials for lithium batteries?