The choice and dosage of both the carbon black and organic expander plays a major role in the charge behaviour of the negative active-material (NAM). Numerous investigations have demonstrated the life of lead–acid batteries in partial state-of-charge (PSOC) operation can be increased dramatically by the use of carbon additives in the NAM and that these additives can also increase charge-acceptance. Unfortunately, in some investigations, an undesirable increase in water loss and diminished cold-cranking performance occurred when a high content of carbon black was paired with a low content of organic expander. Consequently, these complicated responses warrant a systematic investigation to elucidate the relationship between the carbon black, the organic expander, and battery performance. The presentation presents data obtained from 2-V cells in a surface-response ‘design of experiments’ in which loadings of high surface-area carbon black (Cabot PBX135) and organic expander (Borregaard Vanisperse DCA) were varied and the resulting effects on capacity, dynamic charge-acceptance, cold-cranking and PSOC life were measured. Computer software enabled determination of the statistical validity/significance of the effects/differences, and detected correlations ― either positive or negative ― between factors and responses.
Senior Research Associate
Tim has a Master’s Degree in Chemistry from Wayne State University, USA. He joined Borregaard LignoTech in 1996 and is now the global Technical Application Manager for Batteries. His work has focused on developing innovative organic additives to improve the performance parameters of lead–acid batteries. Tim has presented papers at several ELBC and ABC conferences and holds a patent for organic expander compositions.