Evaluation of cast-on-strap joints in lead-acid batteries

The effects of various processing parameters on the lug–strap joint quality of lead-acid auto-batteries are investigated using a laboratory scale cast-on-strap (C.O.S.) set-up. The results indicate that while good quality joints are easily obtained at low cooling rates, at high cooling rate all the C.O.S. parameters such as flux type, strap composition and melt temperature must be carefully controlled to achieve an acceptable joint. Surface treatment with commercially available fluxes, strap melt temperature of 460 °C and strap antimony content of 4.6wt.% Sb render good quality joints at a high strap cooling rate. Furthermore, a dimensionless parameter (relative contact length) for evaluation of lug–strap joint quality is introduced which combines the important lug–strap joint features into a single quantitative parameter and could be used for design of experiments (DOE) and process optimization in the industrial scale.