Development of a Robust Thermal Management System for Lead-Acid Batteries 2021-01-0232
Lead-acid batteries have been widely used in automotive applications. Extending battery life and reducing battery warranty requires reducing any deteriorating to battery internals and battery electrolyte. At the end of battery life, it is required to maintain at least 50% of its initial capacity [1,2]. The rate of battery degradation increases at high battery temperatures due to increased rate of electrochemical reactions and potential loss of battery electrolyte. For Lead-Acid batteries, an electrolyte solution consists of diluted sulfuric acid. Battery electrolyte/water loss affects battery performance. Water loss is caused by high internal battery temperature and gassing off due to battery electrochemistry. High temperatures, high charging rates, and over charging can cause a loss of electrolyte in non-sealed batteries. In sealed batteries, the same factors will cause an increase in temperature and pressure which can eventually result in the release of hydrogen and oxygen gases. Any loss of electrolyte resulting in part of the plates being above the electrolyte surface will result in reduced battery performance. In this paper we present an approach for design of battery thermal protection and selection of charging voltage ranges in order to reduce electrolyte (water) loss and reduce the effects of thermal degradation. Experimental bench test data were gathered at various voltages and at various battery temperatures. A mathematical model was developed to correlate water loss to the battery voltage and temperature. In order to reduce effect of external heating of the battery, thermal simulation tools are applied to assist in selecting the optimum heat shield design. The selected design along with the developed correlations are used in a vehicle level transient thermal analysis model to predict water loss and battery temperature throughout the battery life. Thus a robust approach can be followed for an improved battery thermal management and an improved battery service life and performance.