Modeling the Charge and Discharge Behaviors of an AGM Lead-Acid Battery

Abstract

An absorbent glass mat (AGM) lead-acid battery is a type of valve-regulated lead-acid (VRLA) battery. An AGM lead-acid battery differs from a flooded lead-acid battery in that the sulfuric acid is absorbed in a very fine fiberglass mat, making the battery spill-proof. The leading advantages of AGM type are a higher specific power, lower internal resistance, five times faster charge speed than the flooded version, and the ability to deep cycle. AGM lead-acid batteries are found in high-end vehicles equipped with more electronic devices and making inroads into the start-stop function of cars. A validated mathematical model for the accurate prediction of the charge and discharge behaviors of an AGM lead-acid battery in real-world driving conditions is necessary to ensure that the battery can provide enough power for the rising number of electrical components. In this work, a method of modeling the charge and discharge behaviors of an AGM lead-acid battery under various operating conditions is presented. This work adopts a simple modeling approach by considering Ohm’s law and charge conservation on the electrodes based on the simplified polarization characteristics of the electrodes. By not computing the potential distribution of electrolyte phase and the transport phenomena of ionic species, the modeling method in this work cuts down considerable computation time in comparison with rigorous electrochemical models. The model is validated by comparing the modeling results with the experimental measurements.