The research results of the sealed lead-acid (SLA) batteries of domestic and foreign production are considered. The effect of temperature on the SLA batteries operational performances was investigated. The relationship between the open-curcuit voltage (OCV) and the SLA battery stage-of-charge as well as the relationship between the open-curcuit voltage (OCV) and the battery impedance were determined. The high accuracy of the stage-of-charge diagnosis method based on the battery OCV measuring was proven.
